HEARING SYSTEM COMPRISING A HEARING AID AND AN EXTERNAL PROCESSING DEVICE

Abstract

A hearing system comprises at least one hearing aid (HA) configured to be worn by a user at or in an ear of the user, and an external, portable processing device (EPD). The at least one hearing aid comprises a) at least one HA-input transducer for providing at least one HA-electric input signal representing sound in the environment of the hearing aid; b) a configurable noise reduction system for reducing noise in the at least one HA-electric input signal or in a signal originating therefrom based on a resulting set of noise reduction parameters; c) a noise reduction controller configured to determine a local set of noise reduction parameters; and d) a data receiver configured to receive data via a communication link from the external processing device. The external processing device comprises A) at least one EPD-input transducer for providing at least one EPD-electric input signal representing sound in the environment of the external processing device; B) a parameter estimator for providing an external set of noise reduction parameters configured to reduce noise in the at least one EPD-electric input signal, or in the at least one HA-electric input signal, or in a signal originating therefrom; and C) a data transmitter configured to transmit data, including said external set of noise reduction parameters, via said communication link to the hearing aid. The noise reduction controller is configured to determine said resulting set of noise reduction parameters based on said local set of noise reduction parameters, or on said external set of noise reduction parameters, or on a mixture thereof, in dependence of a noise reduction control signal. A hearing aid and a method of operating a hearing system is further disclosed.

Claims

1. A hearing system comprising at least one hearing aid (HA) configured to be worn by a user at or in an ear of the user, and an external, portable processing device (EPD); the at least one hearing aid comprising: at least one HA-input transducer for providing at least one HA-electric input signal representing sound in the environment of the hearing aid; a configurable noise reduction system for reducing noise in the at least one HA-electric input signal or in a signal originating therefrom based on a resulting set of noise reduction parameters; a noise reduction controller configured to determine a local set of noise reduction parameters; a data receiver configured to receive data via a communication link from the external processing device; the external processing device comprising: at least one EPD-input transducer for providing at least one EPD-electric input signal representing sound in the environment of the external processing device; a parameter estimator for providing an external set of noise reduction parameters configured to reduce noise in the at least one EPD-electric input signal, or in the at least one HA-electric input signal, or in a signal originating therefrom; a data transmitter configured to transmit data, including said external set of noise reduction parameters, via said communication link to the hearing aid, wherein said noise reduction controller is configured to determine said resulting set of noise reduction parameters based on said local set of noise reduction parameters, or on said external set of noise reduction parameters, or on a mixture thereof, in dependence of a noise reduction control signal.

2. A hearing system according to claim 1 comprising a signal quality estimator or separate signal quality estimators configured to estimate an external signal quality parameter of the at least one EPD-electric input signal, or a signal originating therefrom, and a local signal quality parameter of the at least one HA-electric input signal, or of a signal originating therefrom.

3. A hearing system according to claim 2 wherein the noise reduction controller is configured to determine the noise reduction control signal in dependence of the signal quality parameter of the at least one EPD-electric input signal, and/or of the at least one HA-electric input signal, or in a signal originating therefrom.

4. A hearing system according to claim 2 comprising a comparator configured to compare the local signal quality parameter with the external signal quality parameter provided by the signal quality estimators, and wherein the comparator is configured to provide the noise reduction control signal in dependence thereof.

5. A hearing system according to claim 2 wherein the signal quality parameter of the HA- or EPD-electric input signals comprises one or more of a signal to noise ratio, a level, a voice activity parameter, a speech intelligibility indicator, and a bit error rate.

6. A hearing system according to claim 1 wherein the hearing aid is configured to detect whether said external set of noise reduction parameters are received in the hearing aid from the external processing device, and to provide a reception control signal representative thereof.

7. A hearing system according to claim 6 wherein the noise reduction controller is configured to base the resulting set of noise reduction parameters solely on the local set of noise reduction parameters in case no noise reduction parameters are received in the hearing aid from the external processing device as indicated by said reception control signal.

8. A hearing system according to claim 1 configured to base the resulting set of noise reduction parameters on a mixture of the local and external set of noise reduction parameters provided as a weighted combination of the local set of noise reduction parameters and the external set of noise reduction parameters, wherein the weights of a given weighted combination depend on the respective local and external signal quality parameters (SQE-L, SQE-X) of the at least one HA-electric input signal and the at least one EPD-electric input signal.

9. A hearing system according to claim 8 wherein the individual weights of the hearing aid and the external processing device are adapted to scale with their respective signal quality parameters, respectively.

10. A hearing system according to claim 1 comprising a sound scene classifier for classifying an acoustic environment around the hearing system and providing a sound scene classification signal representative of a current acoustic environment around the hearing system.

11. A hearing system according to claim 10, wherein the sound scene classification signal is representative of an estimate of the complexity of the current sound scene.

12. A hearing system according to claim 1 configured to control the communication link to allow enabling/disabling the transmission of data by the external processing device, or reception of data by the hearing aid, in dependence of a link control signal.

13. A hearing system according to claim 12, wherein the hearing system comprises a sound scene classifier for classifying an acoustic environment around the hearing system and providing a sound scene classification signal representative of a current acoustic environment around the hearing system, and wherein the hearing system is configured to control the communication link in dependence of the sound scene classification signal.

14. A hearing system according to claim 1 wherein the parameter estimator of the external processing device comprises a deep neural network.

15. A hearing system according to claim 1 configured to provide a limitation on the noise reduction parameters, e.g. noise reduction gains, applied to the at least one HA electric input signal or to a signal originating therefrom by the noise reduction system of the hearing aid.

16. A hearing system according to claim 15, wherein the hearing system comprises a signal quality estimator or separate signal quality estimators configured to estimate an external signal quality parameter of the at least one EPD-electric input signal, or a signal originating therefrom, and a local signal quality parameter of the at least one HA-electric input signal, or of a signal originating therefrom, wherein the maximum amount of noise reduction depends on said signal quality parameter, or wherein the hearing system comprises a sound scene classifier for classifying an acoustic environment around the hearing system and providing a sound scene classification signal representative of a current acoustic environment around the hearing system, wherein the maximum amount of noise reduction depends on said sound scene classification signal.

17. A hearing system according to claim 1 comprising a distance estimator or a delay estimator configured to estimate a distance or a delay, respectively, between the at least one hearing aid and the external processing device.

18. A hearing system according to claim 17 wherein the distance estimator or the delay estimator is configured to estimate the distance or delay, respectively, between the at least one hearing aid and the external processing device in dependence of a correlation between an envelope of the noise reduction parameters provided by the external processing device and an envelope of the at least one HA electric input signal or of a signal originating therefrom.

19. A hearing system according to claim 18 wherein the noise reduction controller is configured to only apply the noise reduction gain estimates provided by the external processing device if a time lag between the respective envelopes is smaller than a threshold-value.

20. A hearing system according to claim 17 wherein the noise reduction control signal is adapted to depend on the estimated delay between the local set of noise reduction parameters and the external set of noise reduction parameters.

21. A hearing system according to claim 1 wherein the external processing device is configured to be worn or carried by the user or a target talker, and/or to be placed on a surface, e.g. a table.

22. A method of operating a hearing system comprising at least one hearing aid (HA) configured to be worn by a user at or in an ear of the user, and an external, portable processing device (EPD), the method comprising: in the at least one hearing aid: providing at least one HA-electric input signal representing sound in the environment of the hearing aid ; reducing noise in the at least one HA-electric input signal or in a signal originating therefrom based on a resulting set of noise reduction parameters; determining a local set of noise reduction parameters; receiving data via a communication link from the external processing device; in the external processing device: providing at least one EPD-electric input signal representing sound in the environment of the external processing device; providing an external set of noise reduction parameters configured to reduce noise in the at least one EPD-electric input signal, or in the at least one HA-electric input signal, or in a signal originating therefrom; transmitting data, including said external set of noise reduction parameters, via said communication link to the hearing aid; the method further comprising: determining said resulting set of noise reduction parameters based on said local set of noise reduction parameters, or on said external set of noise reduction parameters, or on a mixture thereof, in dependence of a noise reduction control signal.

22. A hearing aid (HA) configured to be worn by a user at or in an ear of the user comprising: at least one input transducer, termed a HA-input transducer, for providing at least one electric input signal, termed a HA-electric input signal, representing sound in the environment of the hearing aid; a configurable noise reduction system for reducing noise in the at least one HA-electric input signal or in a signal originating therefrom based on a resulting set of noise reduction parameters, said resulting noise reduction parameters being determined in dependence of a noise reduction control signal; a noise reduction controller configured to determine a local set of noise reduction parameters; and a receiver configured to receive data via a communication link from an external processing device, including an external set of noise reduction parameters; wherein the noise reduction controller is configured to determine a resulting set of noise reduction parameters based on said local set of noise reduction parameter, or on said external set of noise reduction parameters, or on a mixture thereof in dependence of a noise reduction control signal.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0122] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0123] The aspects of the disclosure may be best understood from the following detailed description taken in conjunction with the accompanying figures. The figures are schematic and simplified for clarity, and they just show details to improve the understanding of the claims, while other details are left out. Throughout, the same reference numerals are used for identical or corresponding parts. The individual features of each aspect may each be combined with any or all features of the other aspects. These and other aspects, features and/or technical effect will be apparent from and elucidated with reference to the illustrations described hereinafter in which:

[0124] FIG. 1 shows an embodiment of hearing system according to the present disclosure,

[0125] FIG. 2 shows a scenario showing how an externally estimated gain may be applied in a hearing aid,

[0126] FIG. 3 shows an embodiment of a hearing system using the same analysis filter bank in the external processing device as in the hearing aid may increase the probability that the externally estimated gain is time-aligned with the hearing aid, when applied,

[0127] FIG. 4 shows an embodiment of hearing system according to the present disclosure wherein the external processing device contains more than one microphone allowing the externally estimated gain to be based on spatial properties, to provide better gain estimates,

[0128] FIG. 5 shows a hearing aid configured to receive an estimated gain from an external processing device according to the present disclosure,

[0129] FIG. 6 shows an embodiment of hearing system according to the present disclosure wherein the external processing device contains a sound scene classifier configured to control transmission of the external set of noise reduction parameters to the at least one hearing aid,

[0130] FIG. 7A shows noise reduction gains as estimated based on microphones in respective left and right hearing aids, and in external processing devices located in first and second distances from the left (reference) microphone (where the first distance is smaller than the second distance); and

[0131] FIG. 7B shows the noise reduction gains (termed the reference gain) provided by the left hearing aid on the basis of the signal from the left (reference) microphone (as in FIG. 7A) and differences between the reference gains and 1) the right microphone gains, 2), 3) the microphone gains of the external processing device when located at the first and second distance, respectively, from the reference microphone,

[0132] FIG. 8 shows correlation between the level of a noisy microphone signal picked up by a hearing aid microphone at an ear of a user and an SNR estimate or a voice activity pattern of a signal picked up by a microphone of an external processing device,

[0133] FIG. 9 shows an embodiment of a hearing system, comprising a hearing aid and an external processing device, according to the present disclosure, and

[0134] FIG. 10 shows an embodiment of a hearing system comprising and an external processing device, wherein the hearing aid comprises a noise reduction controller according to the present disclosure.

[0135] The figures are schematic and simplified for clarity, and they just show details which are essential to the understanding of the disclosure, while other details are left out. Throughout, the same reference signs are used for identical or corresponding parts.

[0136] Further scope of applicability of the present disclosure will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only. Other embodiments may become apparent to those skilled in the art from the following detailed description.

DETAILED DESCRIPTION OF EMBODIMENTS

[0137] The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. Several aspects of the apparatus and methods are described by various blocks, functional units, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). Depending upon particular application, design constraints or other reasons, these elements may be implemented using electronic hardware, computer program, or any combination thereof.

[0138] The electronic hardware may include micro-electronic-mechanical systems (MEMS), integrated circuits (e.g. application specific), microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), gated logic, discrete hardware circuits, printed circuit boards (PCB) (e.g. flexible PCBs), and other suitable hardware configured to perform the various functionality described throughout this disclosure, e.g. sensors, e.g. for sensing and/or registering physical properties of the environment, the device, the user, etc. Computer program shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, embedded software, firmware, middleware, microcode, hardware description language, or otherwise.

[0139] The present application relates to the field of hearing aids. The disclosure particularly deals with the handling of computationally demanding tasks, e.g. related to noise reduction, e.g. handled by machine learning techniques, such as deep neural networks.

[0140] A setup as illustrated in FIG. 1 is proposed. FIG. 1 shows an embodiment of hearing system according to the present disclosure. The hearing system comprises a hearing aid (here a pair of hearing instruments (HA1, HA2)) and an external processing device (EPD). The hearing instruments (HA1, HA2) are configured to be worn at left and right ears of a user (U). In the case where extra (e.g. computational) help (e.g. extra noise reduction) is needed, the hearing aid user (U) can turn on an external processing device, e.g. attached to his clothes, kept in a pocket, etc. The external device, here termed ‘the external processing device’ (EPD), may contain one or more microphones, a signal processor and a transmitter (and possibly also a receiver). When the external processing device is turned on, it preferably transmits an estimated gain (possibly varying across time and frequency) to the hearing instrument(s), which enhances or maintains time-frequency units in which a desired speech signal is present and attenuates time-frequency units where noise is dominant. The gain may be estimated based on the microphones in the external processing device (EPD). It is assumed that the time frequency units which are dominated by speech as well as noise at the external microphone will be similar to the time-frequency units dominated by speech and noise received in the hearing instruments (HA1, HA2). We thus assume that the estimated gain provided by the external processing device can be applied to the hearing aid microphones as well.

[0141] FIG. 2 shows a scenario showing how an externally estimated gain may be applied to the local hearing aid microphones in a hearing aid (or a pair of hearing aids). The hearing system shown in FIG. 2 comprises a hearing ad (HA) and an external processing device (EPD) configured to allow a communication link (LNK) to be established between them. The hearing aid (HA) and the external processing device (EPD) may e.g. comprise appropriate antenna and transceiver circuitry allowing a wireless (e.g. data communication) link (LNK) to be established. The hearing system may e.g. at least comprise a wireless transmitter (Tx) in the external processing device (EPD) and a wireless receiver (Rx) in the hearing aid (HA), cf. e.g. FIGS. 4, 5, 6). The hearing system may comprise a bidirectional communication link, e.g. allowing audio data to be transferred between the hearing aid (HA) and the external processing device (EPD).

[0142] The external processing device (EPD) comprises a microphone (MX) for picking up sound from the environment of the external processing device. The microphone (MX) provides an external electric input signal (XIN) representative of the sound from the environment. The external processing device (EPD) further comprises a gain estimator (G-EST) for providing an external set of processing parameters, e.g. estimated noise reduction gains (XG), configured to reduce noise in the external electric input signal (XIN) (when applied thereto, or to signal of the hearing aid (HA)).

[0143] The communication link (LNK) may e.g. be configured to allow gains (externally estimated gains, XG) estimated in the gain estimator (G-EST) of the external processing device (EPD) to be transmitted to the hearing aid(s) (HA) and applied there.

[0144] The hearing aid (HA) (or hearing aids) comprises at least one microphone, here two microphones (M1, M2) are shown, for picking up sound from the environment of the hearing aid(s). Each of microphones (M1, M2) provides an electric input signal (x1; x2) representative of the sound from the environment. Each of the microphone paths comprises an analysis filter bank (FB-A) for converting an (e.g. digitized) electric input signal (x1; x2) in the time-domain to an electric signal in the (time-) frequency domain (k, l), each providing a frequency sub-band representation of an electric input signal (X1, X2), where k and l are frequency and time indices, respectively, and k = 1, ..., K, where K is the number of frequency sub-bands. The hearing aid (HA) (or hearing aids (HA1, HA2)) further comprises noise reduction system (DIR, NR) configured to reduce noise components relative to target signal components in the electric input signals. The noise reduction system comprises a directional system (DIR) configured to provide a spatially filtered (beamformed) signal as a weighted combination of the electric input signals (X1, X2). The noise reduction system further comprises a noise reduction algorithm (NR). The noise reduction algorithm may, e.g., be implemented using a post-filter controlled by a noise reduction control signal comprising (resulting) gains (attenuation) for being applied to the spatially filtered signal from the directional system to attenuate remaining noise components in the spatially filtered signal relative to target signal components and to provide a noise reduced signal (Y.sub.NR). The hearing aid (HA) (or hearing aids (HA1, HA2)) further comprises a synthesis filter bank (FB-S) configured to convert a frequency sub-band signal (Y.sub.NR) to a time domain output signal (OUT). The output signal (OUT) is fed to an output transducer (SPK) for presentation to the user (U) as an acoustic signal. The output transducer may alternatively be or comprise an electrode array of a cochlear implant type hearing aid (in which case the synthesis filter bank (FB-S) can be dispensed with) or a vibrator of a bone conduction type hearing aid.

[0145] The directional system (DIR) may contain an adaptive beamformer. The adaptive beamformer may e.g. be an MVDR beamformer, an LCMV beamformer or a generalized eigenvector (GEV) beamformer. The adaptive beamformers may be based on estimates of target covariance and/or noise covariance matrix estimates. Target and noise covariance matrices may be updated based on a voice activity estimator determining whether a time-frequency tile is mainly dominated by speech or by noise. A voice activity estimate may be provided by the external processing device or estimated in combination with the local microphones and the external processing device.

[0146] The at least one hearing aid (HA) further comprises a noise reduction controller (NR-CTR) configured to determine a local set of noise reduction parameters (LG, cf. e.g. FIG. 5) based on the local (hearing aid) electric input signals (X1, X2). The noise reduction controller (NR-CTR) is configured to determine a resulting set of noise reduction parameters (RG, cf. FIGS. 4, 5, 6) based on the local set of noise reduction parameters, or on the external set of noise reduction parameters (XG, received from the external processing device), or on a mixture thereof, in dependence of a noise reduction control signal.

[0147] In the embodiment of FIG. 2, the external set of noise reduction parameters (XG) is received in the hearing aid from the external processing device (EPD), where it is estimated in the gain estimator (G-EST) in dependence of the EPD-electric input signal (xx) from the microphone (MX) of the external processing device (EPD). Simultaneously, a local set of noise reduction parameters is estimated in the noise reduction controller (NR-CTR) based on the local HA-electric input signals (X1, X2).

[0148] It is preferable that the estimated gain has the same frequency resolution (e.g. defined by the number of frequency sub-bands K) as the frequency resolution in the hearing aids. One way to ensure this is to base the gain estimation on the same (type and order of) filter bank in the external processing device as the filter bank available in the hearing aid.

[0149] This is illustrated in FIG. 3 and in FIG. 4 showing the case with more than one microphone in the external processing device (EPD). By using the same filter bank (with similar frequency resolution and same decimation) it we also ensure that the processing delay due to the analysis filter bank in the hearing aid and the external processing device is similar.

[0150] In an embodiment, the filter banks in the hearing device and in the external processing device have the same frequency resolution and decimation (e.g. down-sampling) and the same prototype filters (i.e. same window function). In another embodiment, the filter banks in the hearing device and in the external processing device have the same centre frequency and the same decimation but different prototype filters (e.g. different window function). The prototype filter of the hearing device may e.g. have a wider main lobe and high sidelobe attenuation, whereas the prototype filter of the external processing device may have a narrower main lobe but less sidelobe attenuation.

[0151] In an embodiment, the transmitted noise reduction parameters have been decimated.

[0152] FIG. 3 shows an embodiment of a hearing system according to the present disclosure using the same (type of) analysis filter bank (FB-A) in the external processing device (EPD) as in the hearing aid (HA). This is intended to increase the probability that the externally estimated gain is time-aligned with the hearing aid (HA), when applied in the noise reduction algorithm (NR) of the hearing aid (HA). The embodiment of FIG. 3 is identical to the embodiment of FIG. 2 apart from the analysis filter bank (FB-A) inserted in the microphone path of the external processing device (EPD). The analysis filter bank (FB-A) is configured to convert the (e.g. digitized) electric input signal (xx) in the time-domain to an electric signal (XX) in the (time-) frequency domain (k, l), each providing a frequency sub-band representation of the electric input signal (xx), where k and I are frequency and time indices, respectively, and k = 1, ..., K, where K is the number of frequency sub-bands. The parameters defining the configuration of the analysis filter bank (FB-A) of the external processing device (EPD) are identical to the parameters defining the configuration of the analysis filter bank(s) (FB-A) of the hearing aid(s) (HA).

[0153] FIG. 4 shows an embodiment of hearing system according to the present disclosure wherein the external processing device (EPD) contains more than one microphone (MX1, MX2) providing respective (e.g. digitized) time-domain electric input signals (XX1, XX2) allowing the externally estimated gain (XG) to be based on spatial properties, to provide better gain estimates. The embodiment of FIG. 4 is identical to the embodiment of FIG. 3 apart from the external processing device (EPD) comprising a further microphone path (comprising microphone (MX2) providing further external electric input signal (XX2) and corresponding analysis filter bank (FB-A) providing EPD-electric input signal in the (time-) frequency domain (k, l), as frequency sub-band signal (XX2). The gain estimator (G-EST) for providing estimated gains (XG) of the embodiment of FIG. 4 thus receives two microphone input signals (XX1, XX2) in the time-frequency domain. The gain estimator (G-EST) may thus comprise a directional system to improve the estimation of the noise reduction gains (XG) in the external processing device (EPD). This may e.g. be achieved using a conventional target cancelling beamformer (blocking matrix) to estimate noise in the target signal (see e.g. EP2701145A1, or EP3253075A1). The gain estimator (G-EST) may further comprise a voice activity detector providing (e.g. on a frequency sub-band level) an estimate of the presence (or a probability of the presence) of speech in an electric input signal (e.g. XX1 or XX2) or in a signal derived therefrom (e.g. a beamformed signal). Thereby beamformer weights of the directional system may be adaptively updated. A voice activity estimator, an SNR estimator or similar may be used to update the target and/or noise covariances based on the local microphone signals.

[0154] The hearing aid (HD) comprises a data receiver (Rx) configured to receive data via a communication link (LNK) from the external processing device (EPD). The external processing device (EPD) comprises a data transmitter (Tx) configured to transmit data, including an external set of noise reduction parameters (XG), via the communication link (LNK) to the hearing aid (HD). The hearing system is configured to control the communication link (LNK) to allow enabling/disabling the transmission of data by the external processing device, or reception of data by the hearing aid, in dependence of a link control signal. In the embodiment of FIG. 4, the external processing device (EPD) comprises a sound scene classifier (SSC) for classifying an acoustic environment around the hearing system and providing a sound scene classification signal (SSCS) representative of the current acoustic environment around the hearing system. The sound scene classifier may be configured to classify the current acoustic environment around the hearing system according to its complexity for a hearing impaired person. In the embodiment of FIG. 4, the hearing system is configured to control the communication link (LNK) in dependence of the sound scene classification signal (SSCS). The external processing device may be configured to enable transmission of data to the hearing aid in dependence of the sound scene classification signal, e.g. when the sound scene classification signal represents a complex sound scene. Hence, only if the sound scene is estimated to be complex, the hearing aid may receive data from the external device (including the external set of noise reduction parameters, XG).

[0155] An advantage of using an externally estimated gain (XG) is that the external processing device due to its less strict constraints on size and power consumption may contain additional microphones (e.g. two or more) as well as much more processing power (than the hearing aid). The external processing device may not be subject to the same size constraints as apply to a typical hearing aid adapted for being located at or in an ear of a user. The external processing device (EPD) may be configured to be kept in a pocket of the user, or to be attached to the body or to clothing of the user (to allow microphone(s) of the external processing device to be directly ‘accessible’ for sound impinging on the user).

[0156] Also, it is an advantage that only estimated gains (XG) (plus optional control signals) have to be transmitted to the hearing instrument (as opposed to a full audio signal or signals). Compared to transmitting an audio signal, transmitting a gain requires less bandwidth. Hereby it is possible to transmit more frequently (e.g. via a magnetic link, an FM-link or an RF link (e.g. Bluetooth low energy (BLE) or ultra wideband technology (UWB)), such as transmitting every millisecond or every second millisecond (e.g. using an update transmit frequency f.sub.UT ≥ 0.5 kHz, or f.sub.UT ≥ 1 kHz). Hereby the latency due to transmission can be minimized and ensure a better time alignment between the externally estimated gain and the signal in the hearing devices.

[0157] Furthermore, an advantage of applying the external gain to the local microphone signals rather than e.g. transmitting an enhanced audio signal from the external processing device is that spatial cues, such as interaural time (ITD) and level differences (ILD), are better maintained in the audio signal presented to the listener when based on the sound picked up at the local microphones near each ear.

[0158] The more processing power may e.g. allow the estimation of gains using a (e.g. large) deep neural network (DNN). In other words, the gain estimator (G-EST) may comprise (or be constituted by) a deep neural network. DNNs may as well be used to estimate other parameters such as SNR or voice activity.

[0159] The neural network may be trained on various sound scenes. Even though the input features are based on the microphones of the external processing device, an ideal target gain used during training may be based on either the external microphones, the microphones in one or both of the hearing aids or a target gain derived from a combination of all available microphones. In an embodiment, separate gain patterns are transmitted from the external processing device to each hearing instrument.

[0160] In another embodiment, the gain estimator (G-EST) of the external processing device (EPD) is able to estimate multiple audio signals and transmit separate gains for different target audio signals simultaneously. E.g. the external processing device may be able to separate several simultaneous talkers and transmit a gain belonging to each separate signal. The external processing device may be able to transmit a separate gain for the user’s own voice (cf. e.g. FIG. 5). The signal separation scheme may be based on spatial properties of the signals, i.e. different talkers come from different spatial directions. Especially the user’s own voice also arrive from a specific spatial direction. Such processing schemes may be implemented in parallel in order to estimate several gain/snr/voice activity patterns in parallel.

[0161] Also a deep neural network may be trained to recognize specific voices, such as the user’s own voice. Transfer learning may be used rather than retraining a full neural network. E.g. only the last layers of the network need to be re-trained for separation of a specific users’ voice.

[0162] As the gain estimated in an external processing device possibly may remove noise completely, the hearing instrument may limit the maximum amount of noise reduction. The maximum amount of attenuation may depend on the complexity of the environment, e.g. at low input levels or at high SNR, it may not be necessary to remove noise. The amount of noise reduction may also depend on a sound scene classifier (SSC). The hearing aid may comprise a (or the) sound scene classifier (or an SNR estimator or a level estimator e.g. a noise level estimator).

[0163] In the embodiment of FIG. 4, a (or the) sound scene classifier is implemented in the external processing device (EPD), and information on the sound scene is transmitted to the hearing aid(s) (HA), cf. transmitted signal XG*. The hearing system may be configured to transmit the sound scene classification signal (SSCS) indicative of a complexity of the current sound scene around the hearing system from the external processing device (EPD) to the hearing aid (HA, e.g. to the noise reduction controller (NR-CTR)). The transmitted signal (XG*) may thus comprise the external set of noise reduction parameters (XG) (e.g. estimated noise reduction gains) as well as the sound scene classification signal (SSCS) (and optionally other control signals from the external processing device). Thereby the noise reduction controller (NR-CTR) may control the resulting noise reduction gain in dependence of the complexity of the current acoustic environment (sound scene, cf. signal SSCS).

[0164] In an embodiment, a gain estimated from the local hearing aid microphones (M1, M2) (‘the local set of noise reduction parameters’) is combined with the gain (XG) received from the external processing device (EPD) (‘the external set of noise reduction parameters’). In the embodiment of FIG. 4, this is performed in the noise reduction controller (NR-CTR). The combination may e.g. be based on a maximum or a minimum operator. Something similar may apply for externally estimated VAD estimates.

[0165] In a setup, where the transmission from the external processing device to the hearing aid is mono-directional (i.e. no transmission of data from hearing aid to external processing device), it may be necessary to determine if the external processing device is sufficiently close to the hearing instrument (otherwise the estimated time-frequency gain from the external processing device may be misaligned with the local microphone signals). If the microphones of the hearing device(s) are close to the microphones of the external processing device, such as closer than a threshold value, e.g. 30 centimetres or more, e.g. less than 1.5 m, it is expected that the received audio signals are highly correlated, with a time of arrival difference less than one millisecond. As the envelope of the received gain pattern is well correlated with the local microphone signal, we may determine the time lag between the received gain pattern and the local microphone signal (or a signal derived from the local microphone signal(s), such as an envelope signal). Only if the time lag is smaller than a pre-determined threshold (e.g. 1 ms or 2 ms), the external gain will be applied in the local hearing device, see FIG. 8 below. Alternatively, the quality of the transmission link may be used to qualify the external signal. E.g. an external signal with poor signal strength or many drop-outs may be too far away from the hearing aid user to provide appropriate processing parameters for the hearing aid(s).

[0166] Rather than either using the external signals or not, the estimated distance/signal quality may as well be used to control how e.g. the local and the external gain may be combined, where low distance/high signal strength may be in favor of utilizing the external gain, and where a longer distance or a poor signal strength may be in favor of utilizing the gains estimated from the local microphones.

[0167] A distance estimate may be used to determine which frequency bands from the external processing device to use, as the low frequency gain estimates may be valid at greater distances than high frequency gain estimates.

[0168] The hearing aid may comprise a distance estimator, and feed a distance estimate (or a control signal indicative thereof) to the noise reduction controller (NR-CTR). The distance estimator may form part of the noise reduction controller.

[0169] In the case of own voice, a high correlation between the local microphones and the received externally estimated gains (XG) is expected, because the own voice will be close to both the hearing instrument and the external microphone signal, if the external device is worn on the user’s body.

[0170] On the other hand, in the case where the external microphone is not close to the user’s mouth, we will notice that the delay of the received estimated own voice gain (or own voice signal, if that is transmitted) is delayed compares to the locally picked up own voice signal. The advantage of using the own voice scenario compared to other acoustic scenes is that the mouth relative to the hearing instruments is in a fixed setup, and we can detect own voice locally.

[0171] So compared to all external sounds we have a better estimate of whether the external device is close to the user or further away. It may thus be advantageous to estimate the time lag of maximum correlation based on time frames (or time-frequency units) when own voice is estimated by the local microphones. This is illustrated in FIG. 5.

[0172] FIG. 5 shows a hearing aid (HA) configured to receive an external set of noise reduction parameters (e.g. estimated gains (XG)) from an external processing device (EPD, see e.g. FIGS. 1-4, according to the present disclosure. The hearing aid (HA) of FIG. 5 is similar to the embodiments of a hearing aid of FIGS. 2-4 but additionally comprises an own voice beamformer (OVBF) configured to estimate the user’s own voice. In the embodiment of FIG. 5, the own voice beamformer (OVBF) forms part of the noise reduction controller (NR-CTR)). The own voice beamformer (OVBF) receives the first and second HA-electric input signals (X1, X2) in a frequency sub-band representation. The own voice beamformer (OVBF) comprises (predetermined or adaptively updated) beamformer weights that when applied to the first and second electric input signals (X1, X2) provides an estimate (OVE) of the user’s own voice. The hearing aid (HA) of FIG. 5 (here the noise reduction controller (NR-CTR)) further comprises a controller (DECI) configured to decide whether or not or with what weight to apply the externally estimated gains (XG) in the noise reduction algorithm (NR) of the hearing aid (HA). The noise reduction controller (NR-CTR) is configured to determine a local set of noise reduction parameters (LG). The local set of noise reduction parameters (LG) are provided by a local parameter estimator (LOCG) in dependence of the local HA-electric input signals (X1, X2), and optionally further control signals. The noise reduction controller (NR-CTR) may e.g. comprise a voice activity detector (e.g. on own voice activity detector) configured to (e.g. continuously) provide an estimate (e.g. a probability) that a given electric input signal or a signal originating therefrom (at a given time) comprises speech (e.g. speech of the user). Such detector(s) may be advantageous in case beamformer weights are adaptively determined (e.g. updated during use of the hearing system). An external voice activity detector signal may e.g. be used to update estimates of own voice and noise covariance matrices for enhancement of own voice.

[0173] If own voice is detected, the external device may be set in a mode, where it not only transmits a noise reduction parameter, but also transmits the own voice signal picked up by the microphones. Typically, own voice will not be presented to the hearing aid user (but e.g. transmitted via a phone during a phone conversation.) Thus, the processing delay is less critical, and both processing delay and transmission delay can better be tolerated. We may thus take advantage of transmitting an own voice signal, simply because the delay is less time critical (we have better time to process and transmit this signal compared to other signals).

[0174] When the externally determined gain (XG) is transmitted, it is important that the external processing device (EPD) is not too far from the local hearing instrument (e.g. ≤ 0.5 m). If the external microphone(s) and the local microphone(s) are, located relatively close to each other, we will expect that the signals are more time-aligned compared to when the microphones are located further from each other. In particular, when own voice is detected at the local microphones, we would expect the time delay between the own voice signal picked up by the external processing device (by its microphone(s)) and the own voice signal picked up by the hearing aid microphone(s) to be within a certain range, if the external processing device (including its microphone(s)) is correctly mounted (e.g. ≤ 0.5 m from the hearing aid(s)). We may find the time delay during presence of own voice (where we would expect a sufficiently high SNR at all microphones, because of the small distance to the sound source (mouth of the user)) by comparing the waveform of the own voice signal (OVE, in time and frequency) to the waveform of the received gain (XG), cf. e.g. FIGS. 7A, 7B. This may be done in the controller (DECI) forming part of the noise reduction controller (NR-CTR) of FIG. 5 and used to decide whether or not the externally determined gains (XG) shall be used in a current situation. The externally determined gains (XG) may e.g. be applied in the hearing aid(s), if it is detected that the external processing device (EPD) is correctly mounted (in an appropriate distance from the hearing aid(s)). The externally determined gains (XG) may, however, be disabled during own voice and applied only to other speech signals (e.g. controlled by the controller (DECI)).

[0175] In order to minimize the processing latency, we propose a hearing aid system (see e.g. FIGS. 1, 2, 3, 4, 6) with [0176] Hearing aid(s) mounted at the ear(s) with local microphones (see e.g. FIGS. 1-6). [0177] An external processing device with at least one microphone (see e.g. FIGS. 1, 2, 3, 4, 6). [0178] A transmitter capable of continuously transmitting estimated gains from the external processing device to the hearing instruments. [0179] A receiver for receiving externally determined gains and configured to be integrated with locally determined gains in the hearing instruments. [0180] If no external gain is received, the hearing instrument processing will solely be based on the local gain estimates. [0181] The externally determined gains may be estimated based on a deep neural network.

[0182] An advantage of the present disclosure is that no signals (necessarily) need to be transmitted from the hearing aid to the external processing device (whereby power can be conserved in the hearing aid).

[0183] FIG. 6 shows an embodiment of hearing system according to the present disclosure wherein the external processing device contains a sound scene classifier configured to control transmission of the external set of noise reduction parameters to the at least one hearing aid. The embodiment of a hearing system of FIG. 6 is similar to the embodiment of FIG. 4. A difference is that the external processing device of the embodiment of FIG. 6 only comprises a single microphone (MX1) providing a (e.g. digitized) electric input signal (xx) in the time-domain (as in FIG. 3). The sound scene classifier (SSC) thus determines the sound scene classification signal (SSCS) based only on the single (time-frequency domain) electric input signal (XX). Likewise, the noise reduction parameter estimation unit (G-EST) determines the external set of noise reduction parameters (XG, e.g. gains) based only on the single (time-frequency domain) electric input signal (XX). A further difference is that the embodiment of FIG. 6 comprises a hearing aid processor (PRO) for processing the noise reduced signal (Y.sub.NR) from the noise reduction system (NRS) of the hearing aid (HA). The hearing aid processor (PRO) may e.g. be configured to apply one or more processing algorithms to the noise reduced signal (Y.sub.NR) to compensate for a hearing impairment of the user. The processed output signal (OUT) from the hearing aid processor (PRO) is provided to the output transducer (SPK) via the synthesis filter bank (FB-S). The noise reduction controller (NR-CTR) of the embodiment of FIG. 6 may e.g. be configured as described in connection with any of FIGS. 2, 3, 4, 5. The noise reduction controller (NR-CTR) may e.g. comprise a distance estimator for providing an estimate of a current distance between the hearing aid(s) and the external processing device. The distance estimate may e.g. be based on transmission quality (e.g. bit error rate) or on a relation between transmitted and received power (e.g. signal strength) of the wireless data communication link (LNK) between the external processing device and the hearing aid(s).

[0184] The external set of noise reduction parameters may include speech/voice activity estimates, signal-to-noise ratio estimates, or gain estimates.

[0185] FIG. 7A shows four exemplary noise reduction gains as estimated based on microphones in respective left and right hearing aids, and in external processing devices located in first and second distances from the left (reference) microphone (where the first distance is smaller than the second distance).

[0186] FIG. 7B shows noise reduction gains provided by the left hearing aid (termed the reference gains) on the basis of the signal from the left (reference) microphone (as in FIG. 7A) and differences between the reference gains and 1) the gains determined in the right hearing aid based on the right microphone, and between the reference gains and the microphone gains of the external processing device when located at the first 2) and second 3) distance, respectively, from the reference microphone.

[0187] The plots of FIGS. 7A, 7B represent so-called spectrograms representing gain (or gain differences), e.g. real values (magnitudes) thereof, versus frequency ([Hz]) (vertical axis) and time ([s]) (horizontal axis). The illustrated frequency range is between 0 and 8000 Hz, which is a normal range of operation of a hearing aid. The illustrated time range is between 0 and 2 s. The plots represent a short time segment of speech in noise for which appropriate noise reduction gains (attenuation) have been calculated in the respective devices, where the sound is picked up (cf. FIG. 7A). The four devices in question are 1) left and 2) right hearing aids, and 3), 4) external processing devices located close to (≈0.3 m from) the left hearing aid and farther away (≈3 m) from the left hearing aid, respectively.

[0188] In order to justify the use of an externally estimated microphone gain, ideally estimated binary gains based on a collocated target and noise signal have been calculated and displayed in FIGS. 7A, 7B. The difference between the different gain patterns (FIG. 7B) are thus mainly given by the difference in transfer functions from the source to the different microphones. As we see the dark grey areas where target signal components dominate are very similar at the different microphone positions, i.e. left ear, right ear, chest (e.g. ≈0.3 m from the ears) and a remote microphone (e.g. ≈3 m from the ears). When the target occupies the same areas in time and frequency (time-frequency units), we may as well apply a gain estimate derived from the external processing device (e.g. located on the chest, denoted ‘the chest microphone’) to the left microphone signals.

[0189] However, the further away the external microphone is from a reference microphone position (in FIG. 7B, e.g. chosen to be a microphone of a hearing aid located at the left ear of the user), the more deviation we see between the time-frequency units where speech is active (see FIG. 7B).

[0190] The light grey areas (time-frequency units) in FIG. 7B shows the time frequency units of speech activity (or noise activity deviating from the (left)reference microphone. Especially, we see a deviation for the remote microphone - mainly due to the fact that the microphone is further away from the reference microphone (e.g. ≈3 m), and the speech activity pattern is thus delayed in time. In the upper left corner of FIG. 7B, the light grey areas show noise activity. In the other images, the light grey areas show the differences of speech/noise activity of the different microphones compared to the upper right reference microphone (we do not distinguish between whether the difference is due to noise/speech or speech/noise differences).

[0191] Instead of binary noise reduction gains (as exemplified in FIGS. 7A, 7B), however, the binary gains, may be interpreted as a binary voice activity estimate indicating whether speech is present or absent in a given time-frequency tile.

[0192] FIG. 8 shows correlation between the level of a noisy microphone signal picked up by a hearing aid microphone at an ear of a user and an SNR estimate or a voice activity pattern of a signal picked up by a microphone of an external processing device>.

[0193] The top plot shows corresponding (simultaneously recorded) time segments (of 0.4 s duration) of three time-variant signals ([dB] versus time [s]). The bold solid line graph (denoted ‘1)’) shows the level of an exemplary noisy microphone signal picked up by a microphone (of a hearing aid) at an ear of a user (e.g. the left ear). The thin solid line graph (denoted ‘2)’) shows an SNR estimate obtained from a chest microphone (located at the chest of the user), and the dashed line graph (denoted ‘3)’) shows an SNR estimate obtained from a (more) remote microphone picked up farther from the user than the chest microphone.

[0194] The lower plot illustrates how the level of the noisy microphone signal (in a single frequency channel) is correlated with the SNR estimate obtained from a) the chest microphone (bold solid line graph, denoted ‘A’), and b) the (more) remote microphone (dashed line graph, denoted ‘B’). The lower plot further illustrates how the level of the noisy microphone signal (in a single frequency channel) is correlated with the voice activity pattern of a signal picked up by a chest microphone (located at the chest of the user, solid line graph, denoted C).

[0195] It can be concluded that the correlation between either microphone signals, gain, voice activity, or SNR estimates can be used to determine if the gain is obtained from a microphone located close to the reference microphone (here a microphone of a hearing aid at a left ear of the user) or a microphone located further away. The closer the microphone is to the reference microphone the more likely it is that the maximum correlation is close to lag 0. But a distance between the hearing aids and the external processing device (e.g. a chest microphone) below a threshold allows the use of parameters of microphone signals picked up in the external processing device to be used ‘directly’ in the hearing aid. The plot disregards any additional transmission delay. (i.e. delay due to transmitting multiple frames simultaneously). As only little data need to be transmitted, it may be advantageous to transmit frequently, e.g. every millisecond, every second millisecond or with a rate of 200 Hz or 100 Hz. The gain may as well be low-pass filtered and down-sampled before transmitted. The transmission link may be based on an inductive link, an FM signal, or Bluetooth low energy (BLE), or UWB.

[0196] Noise reduction parameters estimated in the external processing device and transmitted to the hearing aid(s) for being used therein may e.g. be noise reduction gains. But other parameters may be used. The transmitted data from the external processing device may be an SNR estimate (which may be converted into a gain after the signal is received at the hearing aid, e.g. by an SNR to gain conversion algorithm, e.g. implemented as a Wiener gain curve).

[0197] A criterion for using the gain obtained from the external processing device, e.g. a chest microphone, may involve a direction of arrival of the target signal. If the target is from the front, it is easily picked up by the chest microphone, but if the target signal is impinging from behind the user, the target may be more attenuated at the chest microphone, as the target signal has to pass around the body on its way from the source to the microphone. On the other hand, a chest microphone may be better at attenuating noise from behind (compared to noise picked up by a hearing aid microphone), as the noise will be shadowed by the body. This implies that the user may benefit more from a chest microphone signal when the target is in front of the listener. The selection between using a gain obtained from the local hearing aid microphones and a chest microphone may thus be determined based on a DOA estimate on the local microphone: if a target talker is from the back, it may be better to use local microphone gains; otherwise, if the target talker is from the front, the external microphone gain may be better to apply at the hearing aid microphones.

[0198] FIG. 9 shows an example of a hearing system (HS), comprising a hearing aid (HA) and an external processing device (EPD), according to the present disclosure comprising a similar functional configuration as in FIG. 4, but without the sound scene classifier (SSC) in the external processing device (EPD). As in FIG. 4, the external processing device (EPD) contains more than one microphone, here two (MX1, MX2), providing respective (e.g. digitized) time-domain electric input signals (xx1, xx2) allowing the externally estimated gain (XG) to be based on spatial properties, to provide better gain estimates. The embodiment of FIG. 4 comprises respective analysis filter banks (FB-A) providing the electric input signals of the hearing aid (HA) and the external processing device (EPD) in the (time-) frequency domain (k, l), as frequency sub-band signals (X1, X2) and (XX1, XX2), respectively. Instead of analysis filter banks in the microphone paths of the hearing aid (HA) and the external processing device (EPD), the embodiment of FIG. 9 comprises respective low latency encoders (LL-ENC) configured to convert first and second streams of samples of electric input signals (x1, x2) of the hearing aid (HA) and first and second streams of samples of electric input signals (xx1, xx2) of the external processing device (EPD) in the time domain to respective streams of samples of the electric input signals in a second domain (Y; XY).

[0199] The hearing aid (HA) of FIG. 9 comprises a forward path comprising the (here two) microphones (M1, M2), respective low-latency encoders (LL-ENC) providing electric input signal(s) (Y) in the high dimensional domain, a combination unit (‘X’, here a multiplication unit), a low-latency decoder (LL-DEC) and an output transducer (SPK, here a loudspeaker). The estimated gains (XG), received by wireless receiver (Rx) in the hearing aid (HD) from the external processing device (EPD), are applied to the electric input signal(s) (Y) in the high dimensional domain in the combination unit (‘X’) of the hearing aid (HA) and the resulting processed signal (OOT) is fed to the low-latency decoder (LL-DEC) of the hearing aid (HA) providing a processed (time-domain) output signal (out). The processed output signal (out) is fed to the loudspeaker (SPK) of the hearing aid (HA) for presentation to the user as a hearing loss compensated sound signal.

[0200] The gain estimator (G-EST) of the external processing device (EPD) for providing estimated gains (XG) of the embodiment of FIG. 9 may receive two microphone input signals (XY) in the high dimension domain. The gain estimator (G-EST) may thus be configured to estimate gains (XG) for the two electric input signal(s) (Y) in the high dimensional domain of the forward path of the hearing aid. The estimated gains (XG) in the high dimensional domain are transmitted to the hearing aid (HA) via the wireless link (LNK) by transmitter (Tx) of the external processing device.

[0201] FIG. 9 shows a more general setup than FIG. 4. The encoder (LL-ENC) in the hearing instrument (HA) of FIG. 9 is similar to the encoder (LL-ENC) in the external processing device (EPD). The encoder may e.g. be an analysis filter bank or a trained neural network. The gain (XG) provided by the gain estimator (G-EST) of the external processing device may be estimated using a neural network under the constraint that the gain is time-aligned with the signal in the hearing device (e.g. by taking transmission delay into account).

[0202] The concept of low latency encoders and low latency decoders used in a hearing system is described in more detail in our co-pending European patent application number EP4099724A1.

[0203] FIG. 10 shows an embodiment of a hearing system (HS) comprising a hearing aid (HA) and an external processing device (EPD), wherein the hearing aid comprises a noise reduction controller (NR-CTR) according to the present disclosure. The embodiment of a hearing system shown in FIG. 10 comprises some of the same elements that are shown and described in connection with the embodiments of FIGS. 2, 3, 4, 5, 6, and 9. The features of the embodiment of a hearing system shown in FIG. 10 is intended to be combinable with the features of the embodiments of FIGS. 2, 3, 4, 5, 6, and 9.

[0204] The (at least one) hearing aid (HA) is configured to be worn by a user at or in an ear of the user. The hearing aid comprises an input unit (IU) comprising at least two input transducers, each providing at least one electric input signal representing sound in the environment of the hearing aid (HA). The input unit may e.g. comprise respective analysis filter banks for providing the (e.g. two) electric input signals (X1, X2) in a time-frequency representation (k,l), k and l being frequency and time indices, respectively. The electric input signals (X1, X2) may be arranged as consecutive time frames (l=1, 2, ..., l′, ...), each representing a frequency spectrum of the input signal in question with discrete (generally complex) values of the signal in question in each time frequency unit (k, 1′), where the frequency index, k = 1, ..., K, and where K is smaller than or equal to the number of frequency bands provided by the analysis filter bank. The hearing aid (HA) further comprises a configurable noise reduction system (NRS) for reducing noise in the electric input signals (X1, X2) or in a signal originating therefrom (e.g. a beamformed signal, cf. e.g. FIGS. 2-5) based on a resulting set of noise reduction parameters (RG). The hearing aid (HA) further comprises a noise reduction controller (NR-CTR) configured to determine a local set of noise reduction parameters (LG), e.g. gains, to be applied to the electric input signals of the hearing aid (or to a signal or signals originating therefrom, e.g. a beamformed signal). The local set of noise reduction parameters (LG) may e.g. be dependent on the electric input signals (X1, X2) of the hearing aid (HA) and optionally one or more detectors, e.g. a voice activity detector. The hearing aid (HA) further comprises a data receiver (RX) configured to receive data via a communication link (LNK) from the external processing device (EPD).

[0205] The exemplary hearing aid (HA) of FIG. 10 further comprises a hearing aid processor (PRO) for processing the noise reduced signal (Y.sub.NR) from the noise reduction system (NRS) of the hearing aid (HA). The hearing aid processor (PRO) may e.g. be configured to apply one or more processing algorithms to the noise reduced signal (Y.sub.NR) to compensate for a hearing impairment of the user. The processed output signal (OUT) from the hearing aid processor (PRO) is provided to an output unit (OU) of the hearing aid (HA). The output unit (OU) may e.g. comprise a synthesis filter bank, cf. FB-S in FIG. 6 (for converting the processed output signal (OUT) in the (time-)frequency domain to a signal in the time-domain) and an output transducer, e.g. a loudspeaker (SPK as in FIG. 6) and/or a vibrator of a bone conduction hearing aid.

[0206] The external processing device (EPD) comprises at least one input transducer (MX), here one microphone) for providing at least one electric input signal (xx) representing sound in the environment of the external processing device (EPD). The microphone path of the input transducer may comprise an analysis filter bank for providing the electric input signal (XX) in a time-frequency representation (k, 1). The external processing device (EPD) further comprises a parameter estimator (G-EST) for providing an external set of noise reduction parameters (XG), e.g. gains, configured to reduce noise in the at least one EPD-electric input signal (XX), or in the at least one HA-electric input signal (X1, X2), or in a signal originating therefrom. The external processing device (EPD) further comprises a signal quality estimator (SQX) configured to estimate a signal quality parameter (SQX-E) of the at least one electric input signal (xx) from the input transducer (MX) of the external processing device (EPD). The signal quality parameter (SQE-X) may e.g. be constituted by or comprise a signal to noise ratio (SNR), or a level (L), a voice activity parameter (e.g. a speech presence probability (SPP)), or a bit error rate (BER), or similar (equivalent) parameters. The external processing device (EPD) further comprises a data transmitter (TX) configured to transmit data, including the external set of noise reduction parameters (XG) and the signal quality parameter (SQE-X), via the communication link (LNK) to a receiver (Rx) of the hearing aid (HA). The communication link (LNK) may e.g. be a wireless link, e.g. based on Bluetooth or Bluetooth Low-Energy (BLE), e.g. Bluetooth LE Audio (or functionally similar, standardized or proprietary, technology).

[0207] The embodiment of a configurable noise reduction system (NRS) of the hearing aid shown in FIG. 10 comprises a beamformer (BF) for providing a beamformed (spatially filtered) signal (Y.sub.BF) as a liner combination of the electric input signals (X1, X2) from the input unit (IU). The electric input signals (X1, X2) er provided by the input unit (IU) (originating from first and second input transducers and transformed into a time-frequency representation (k, 1) by respective analysis filter banks). The configurable noise reduction system (NRS) further comprises a post-filter (PF) receiving the beamformed signal (Y.sub.BF). The post-filter is configured to further reduce noise in the beamformed signal (Y.sub.BF) in dependence of post-filter gains (RG). The (resulting) post-filter gains (RG) are either A) estimated based on the electric input signals of the hearing aid, and termed ‘local post-filter gains’ (LG), or B) estimated based on the electric input signal (or signals) of the external processing device, and termed ‘external post-filter gains’ (XG), or C) a combination (mixture, e.g. a weighted combination) thereof. The local post-filter gains (cf. signals (LG)) are determined in the noise reduction controller (NR-CTR), specifically in the local gain estimator (LOCG) in FIG. 10, e.g. (further) in dependence of the outputs of one or more target cancelling beamformers, whose beamformer weights are e.g. fixed or updated during use, e.g. using a voice activity detector, as is known in the art (see e.g. EP2701145A1).

[0208] An embodiment of the noise reduction controller (NR-CTR) as shown in FIG. 10 will be described in further detail in the following.

[0209] The noise reduction controller (NR-CTR) receives as inputs:

[0210] From the hearing aid (HA), [0211] a) the electric input signals (X1, X2) from the input unit (IU); and [0212] from the external processing device (EPD) via the data communication link (LNK), [0213] b) the external post-filter gains (XG) (termed XG* in the hearing aid after reception in the receiver (RX)), and [0214] c) the signal quality parameter (SQE-X) ((termed SQE-X* in the hearing aid) representative of the signal quality of the at least one electric input signal (xx) from the input transducer (MX) of the external processing device (EPD).

[0215] The noise reduction controller (NR-CTR) of the hearing aid (HA), cf. dotted enclosure denoted NR-CTR in FIG. 10, is configured to determine the resulting set of noise reduction parameters (RG) in dependence of a noise reduction control signal (NRC). As exemplified in FIG. 10 and mentioned above, the noise reduction controller (NR-CTR) comprises local gain estimator (LOCG) for providing the gains (LG) of local origin and a signal quality estimator (SQL) configured to estimate a signal quality parameter (SQE-L) of the at least one electric input signal (X1, X2), e.g. either one of them, or both or a logic combination of them (e.g. an average) from the input unit (IU) of the hearing aid (HA). The noise reduction controller (NR-CTR) further comprises a comparator (COMP) configured to compare the locally estimated signal quality parameter (SQE-L) and the externally estimated signal quality parameter (SQE-X*) received from the external processing device (EPD). Based on the two signal quality parameters, the comparator (COMP) is configured to provide the noise reduction control signal (NRC). If a difference, ΔSQE (or ratio, SQE-L/SQE-X*) between the local signal quality parameter (SQE-L) and the externally estimated signal quality parameter (SQE-X*) is larger than a threshold value (SQE.sub.TH) (indicating that the signal quality of the electric inputs signals of the hearing aid (or of a signal originating therefrom) is (much) larger than the signal quality of the electric input signal(s) of the external processing device), the noise reduction control signal (NRC) may be configured to choose the gains (LG) of local origin as the resulting gains (RG). This choice is made by the decision unit (DECI) which provides the resulting gains (RG) in dependence of the local gains (LG) and the external gains (XG*) controlled by the noise reduction control signal (NRC). If a difference, ΔSQE (or ratio, SQE-L/SQE-X*) between the local signal quality parameter (SQE-L) and the externally estimated signal quality parameter (SQE-X*) is smaller than a threshold value (SQE.sub.TH), the noise reduction control signal (NRC) may be configured (via the decision unit (DECI)) to choose the gains (XG*) of external origin as the resulting gains (RG). If e.g. the difference, ΔSQE (or ratio, SQE-L/SQE-X*) between the local signal quality parameter (SQE-L) and the externally estimated signal quality parameter (SQE-X*) is smaller than a first threshold value (SQE.sub.TH1) and larger than a second threshold value (SQE.sub.TH2), the noise reduction control signal (NRC) may be configured (via the decision unit (DECI)) to choose a combination, e.g. a weighted combination, of the local gains (LG) and the external gains (XG*). The weights of a given weighted combination may be frequency dependent and may depend on the respective signal quality parameters (SQE-L, SQE-X*) of the at least one HA-electric input signal and the at least one EPD-electric input signal. The resulting, combined, (frequency (k) dependent) resulting gains RG(k) = LG(k)W.sub.HA(k) + XG*(k)W.sub.EPD(k), where the individual (e.g. frequency dependent) weights W.sub.HA(k) and W.sub.EPD(k) of the hearing aid and the external processing device, respectively, may be adapted to scale with their signal quality parameters SQP.sub.HA(k) (=SQE-L) and SQP.sub.EPD(k) (=SQE-X*), respectively (‘scale with’ in the meaning ‘larger the larger’ and ‘smaller the smaller’). The signal quality parameters may e.g. be or comprise a signal to noise ratio (SNR) or a speech presence probability (SPP), or a speech intelligibility (SI) estimate, etc.

[0216] The hearing aid (e.g. the receiver RX) may configured to detect whether the external set of noise reduction parameters (XG) are received in the hearing aid (HA) from the external processing device (EPD), and to provide a reception control signal (RxC) representative thereof (cf. dashed arrow from receiver (RX)) to decision unit (DECI)). The noise reduction controller (NR-CTR) is configured to base the resulting set of noise reduction parameters (RG) solely on the local set of noise reduction parameters (LG) in case no noise reduction parameters (XG) are received in the hearing aid from the external processing device as indicated by the reception control signal (RxC).

[0217] It is intended that the structural features of the devices described above, either in the detailed description and/or in the claims, may be combined with steps of the method, when appropriately substituted by a corresponding process.

[0218] As used, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well (i.e. to have the meaning “at least one”), unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, but an intervening element may also be present, unless expressly stated otherwise. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. The steps of any disclosed method are not limited to the exact order stated herein, unless expressly stated otherwise.

[0219] It should be appreciated that reference throughout this specification to “one embodiment” or “an embodiment” or “an aspect” or features included as “may” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Furthermore, the particular features, structures or characteristics may be combined as suitable in one or more embodiments of the disclosure. The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects.

[0220] The claims are not intended to be limited to the aspects shown herein but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more.

REFERENCES

[0221] EP2701145A1 (Oticon) 26.02.2014. [0222] EP3253075A1 (Oticon) 06.12.2017. [0223] EP4099724A1 (Oticon) 07.12.2022. [0224] EP3252766A1 (Oticon) 06.12.2017. [0225] EP3694229A1 (Oticon) 12.08.2020.