Abstract
A hearing system comprises a hearing device worn on the head, or fully or partially implanted in the head, of a user, and external audio transmitters. The hearing system allows wireless communication to be established between the hearing device and the audio transmitters. The hearing device comprises microphones providing respective electric input signals; a beamformer filter providing a beamformed signal from the electric input signals; and an output unit. The hearing system further comprises a selector/mixer for selecting and possibly mixing one or more of the electric input signals or the beamformed signal and external electric signals from the audio transmitters, and providing a current input sound signal based thereon for presentation to the user. The selector/mixer is controlled by a source selection processor, which determines the source selection control signal based on a comparison of the beamformed signal and the external electric sound signals or processed versions thereof.
Claims
1. A hearing system comprising at least one hearing device adapted for being worn on the head, or fully or partially implanted in the head, of a user, and an external audio transmitter, providing an external electric sound signal comprising audio; the hearing system being configured to allow wireless communication, including audio communication, between said hearing device and said external audio transmitter, at least from said external audio transmitter to said at least one hearing device, to be established; the at least one hearing device comprising a multitude of microphones, each providing an electric input signal representative of sound; a beamformer filter providing a beamformed signal from said multitude of electric input signals; and an output unit configured to provide stimuli perceivable by the user as sound, wherein the hearing system further comprises a selector/mixer for selecting and possibly mixing one or more of said electric input signals or said beamformed signal from the hearing device and said external electric signal from the audio transmitter and to provide a current input sound signal based thereon intended for being presented to the user, possibly in a further processed form, the selector/mixer being controlled by a source selection control signal provided by a source selection processor configured to determine said source selection control signal in dependence of a comparison of said beamformed signal and said external electric sound signal or processed versions thereof, and a mixing ratio between the electric input signals or the beamformed signal and the external electric sound signal is determined in dependence of a comparison of the beamformed signal with the external electric sound signal or processed version thereof.
2. A hearing system according to claim 1 wherein said source selection control signal is determined based on a comparison of filtered or down-sampled versions of the beamformed signal with filtered or down-sampled version of said external electric sound signals.
3. A hearing system according to claim 1 wherein said source selection control signal is determined based on a comparison of parameters derived from said beamformed signal with corresponding parameters derived from said external electric sound signal.
4. A hearing system according to claim 3 wherein said parameters comprise one or more of a signal to noise measure, a modulation measure, a level measure.
5. A hearing system according to claim 1 configured to provide that said comparison is performed in the audio transmitter, and wherein a similarity measure indicative of the degree of similarity of the beamformed signal with the external electric sound signal or processed version thereof is determined in said audio transmitter.
6. A hearing system according to claim 5 configured to provide that said similarity measure are transmitted from said audio transmitter to said at least one hearing device or to a processing device in communication with the hearing device.
7. A hearing system according to claim 1 configured to provide that said comparison is performed in the at least one hearing device, and wherein similarity measure indicative of the degree of similarity of the beamformed signal or a processed version thereof with the external electric sound signal or correspondingly processed version thereof is determined in said at least one hearing device.
8. A hearing system according to claim 7 wherein said beamformed signal is a target enhancing beamformer signal configure to enhance a target signal relative to other signals.
9. A hearing system according to claim 1 wherein the beamformed signal is presented to the user instead of the external sound signal, in case its quality is higher than the external electric sound signal.
10. A hearing system according to claim 1 wherein said output unit for providing a stimulus perceived by the user as an acoustic signal based on a processed electric signal comprises a number of electrodes of a cochlear implant (for a CI type hearing device) or a vibrator of a bone conducting hearing device.
11. A hearing system according to claim 1 configured to present the current input sound signal or a further processed version thereof to the user via the output unit.
12. A hearing system according to claim 1 wherein the audio transmitter comprise a microphone unit.
13. A hearing system according to claim 12 wherein said microphone unit comprises a multitude of microphones, each providing a microphone signal, and a beamformer filter, configured to provide a beamformed signal based on the microphone signals picked up by said multitude of microphones.
14. A hearing system according to claim 12 wherein said microphone unit comprises or form part of one or more of a wireless microphone unit, a mobile telephone, and a speakerphone.
15. A hearing system according to claim 1 wherein said at least one hearing device is constituted by or comprises a hearing aid, a headset, an earphone, an ear protection device or a combination thereof.
16. A hearing device adapted for being worn by a user, the hearing device comprising a multitude of microphones, each providing an electric input signal representative of a sound field surrounding said hearing device; a beamformer filter providing a beamformed signal from said multitude of electric input signals; and an output unit configured to provide stimuli perceivable by the user as sound; a wireless transceiver for receiving a signal comprising external electric sound signal from an external audio transmitter, possibly via a processing device, and for transmitting a signal comprising data, to said audio transmitter, possibly via said processing device, a selector/mixer for selecting and possibly mixing one or more of said electric input signals or said beamformed signal from the hearing device and said external electric signal from the audio transmitter and to provide a current input sound signal based thereon intended for being presented to the user, possibly in a further processed form, the selector/mixer being controlled by a source selection control signal, a source selection processor configured to determine said source selection control signal in dependence of a comparison of said beamformed signal and said external electric sound signals or processed versions thereof, wherein a mixing ratio between the electric input signals or the beamformed signal and the external electric sound signal is determined in dependence of a comparison of the beamformed signal with the external electric sound signal or processed version thereof.
17. A hearing device according to claim 16 being constituted by or comprising a hearing aid, a headset, an earphone, an ear protection device or a combination thereof.
18. A method of operating a hearing system comprising at least one hearing device, adapted for being worn by a user, and an external, audio transmitter, said audio transmitter being individual device or forming part of a separate electronic device, providing an external electric sound signal, the method comprising providing an external electric sound signal from said audio transmitter: providing wireless communication, including audio communication, between said at least one hearing device and said external audio transmitter, at least from said audio transmitter to said at least one hearing device; providing a multitude of electric input signals, each being representative of a sound field at said at least one hearing device; providing a beamformed signal from said multitude of electric input signals; and providing stimuli perceivable by the user as sound; providing a source selection control signal in dependence of a comparison of said beamformed signal and said external electric sound signal or processed version thereof; and selecting and possibly mixing one or more of said electric input signals or said beamformed signal from the hearing device and said external electric signal from the audio transmitter to thereby provide a current input sound signal based thereon in dependence of said source selection control signal, said current input signal being intended for presentation to the user, possibly in a further processed form, wherein a mixing ratio between the electric input signals or the beamformed signal and the external electric sound signal is determined in dependence of a comparison of the beamformed signal with the external electric sound signal or processed version thereof.
Description
BRIEF DESCRIPTION OF DRAWINGS
(1) 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:
(2) FIG. 1 shows an exemplary scenario wherein a person wearing hearing instruments (at left and right ears), which are connected (preferable wirelessly) to a grid of (generally randomly distributed) available external microphone units, is located in a room with a one or more sound sources (e.g. talking persons), and one or more noise sources,
(3) FIG. 2 illustrates an embodiment of a method of operating of a hearing system according to the present disclosure, wherein a beamformed signal comprising the target signal provided by one of the hearing instruments of the hearing system is transmitted to the external microphone units for evaluation,
(4) FIG. 3 shows an embodiment a method of operating of a hearing system according to the present disclosure, wherein two beamformed signals, one comprising the target signal, the other not comprising the target signal, provided by one of the hearing instruments of the hearing system are transmitted to the external microphone units for evaluation,
(5) FIG. 4 shows a first exemplary implementation of the similarity measure,
(6) FIG. 5 shows a second exemplary implementation of the similarity measure,
(7) FIG. 6 shows an embodiment a method of operating of a hearing system according to the present disclosure, wherein, contrary to FIG. 2 or 3, all calculations may take place in the user's hearing instrument,
(8) FIG. 7 shows an example of how the user by his head is able to select a talker of interest.
(9) FIG. 8 shows an embodiment of a hearing device according to the present disclosure.
(10) FIG. 9A shows an embodiment of a hearing system, e.g. a binaural hearing aid system, according to the present disclosure; and
(11) FIG. 9B illustrates an auxiliary device configured to execute an APP implementing a user interface of the hearing device or system from which a mode of operation and an active sound source can be selected,
(12) FIG. 10 shows an embodiment of a hearing device or a hearing system according to the present disclosure,
(13) FIG. 11 shows an example of a scenario where several remote microphones have to share the same communication channel, and
(14) FIG. 12 illustrates the scenario of FIG. 11 where several remote microphone units have to share the same communication channel, and where metadata are exchanged between all the microphone units in order to decide which of the audio signals should be transmitted to the hearing device(s).
(15) 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.
(16) 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
(17) 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.
(18) The electronic hardware may include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. 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, firmware, middleware, microcode, hardware description language, or otherwise.
(19) The present application relates to the field of hearing devices, e.g. hearing aids.
(20) FIG. 1 shows an exemplary scenario wherein a person wearing hearing instruments (at left and right ears), which are connected (preferable wirelessly) to a grid of (generally randomly distributed) available external microphone units, is located in a room with a one or more sound sources (e.g. talking persons), and one or more noise sources. In noisy situations, e.g. where multiple persons are talking simultaneously (and further where one or more noise sources are present), it may be advantageous to listen to the sound of one of the available external microphones rather than the sound picked up by the hearing instrument as the signal to noise ratio of the target sound picked up by the external microphones may be much higher compared to the signal to noise ratio available at the microphones located in the hearing instrument(s).
(21) FIG. 1 schematically shows person (U) wearing hearing instruments (HD1, HD2) located in a room together with a number (here three) of persons (A, B, C), which may be simultaneously or sequentially talking. One or more sound sources may be present, as indicated by localized sound (LS) or diffuse sound sources (DN), e.g. reverberation. Besides the hearing instruments (HD1, HD2), each comprising a number of microphones (here two (M1F, M1R) and (M2F, M2R), respectively), a number of external microphones (1, 2, 3, 4) are available. It could e.g. be microphones located in different mobile phones, which potentially could be made available for the hearing instrument user via a wireless connection between the external device and the hearing instrument(s) (HD1, HD2). Alternatively, the wireless microphones (1, 2, 3, 4) could be part of an “enhanced-communication-package” provided by the hearing aid manufacturer. In noisy conditions, such external microphones (1, 2, 3, 4) may be of benefit for the hearing instrument user (U) as the quality (e.g. in terms of signal to noise ratio (SNR)) of the target sound from target sound source (A) picked up by some of the microphones may (1, 2, 3, 4) be better than what may be achieved solely by the microphones ((M1F, M1R), (M2F, M2R)) built into the hearing instrument (HD1, HD2). Utilizing a dynamic external microphone array may be challenging for several reasons: The number of available external microphones (here four) may vary over time. It is assumed that the hearing instrument(s) (HD1, HD2) is(are) able to connect to available external microphones (1, 2, 3, 4). The location of the available microphones (1, 2, 3, 4) relative to the target source candidates (A, B, C) and the hearing aid (U) user may be changing over time, and is generally unknown. The sample rate of the different external microphones (1, 2, 3, 4) may be different from each other as well as different from the sample rate of the hearing instrument(s) (HD1, HD2). Even if the sample rates were similar, the sample time of the different units would not (necessarily) be synchronized. The transmission bandwidth is limited. It may not be possible to exchange all microphone signals simultaneously. It may thus be required to select between the external microphones (1, 2, 3, 4) in order to ensure that the most relevant signal is transmitted to the hearing instrument(s) (HD1, HD2). In one embodiment, a particular wireless device may physically contain several microphones, e.g. two or more, and combine the microphone signals into a single output signal (a beamformed signal), which may then potentially be transmitted to the hearing aid user (U). Different simultaneous talkers (in FIG. 1: A, B), e.g., a target talker (for the user U) and a ‘competing talker’, may be picked up by the external microphone array. A strategy for selecting the target talker from a pool of several target talker candidates is needed. While many manual selection schemes may be envisioned, a selection scheme which does not require the user's active (conscious) involvement is aimed at. The external microphones (1, 2, 3, 4) may have different, unknown processing and transmission latency. This, combined with the fact that the sample rate and the microphone's location are unknown, and the transmission bandwidth is generally limited, makes it practically challenging to combine the signals (e.g., in a beamformer stage at the hearing instrument(s) (HD1, HD2)) in order to improve the signal to noise ratio. In an embodiment, the external microphones may be shared between several hearing instrument users, i.e. each microphone may simultaneously be part of several networks.
(22) In the example of FIG. 1, the user wears first and second hearing devices, e.g. hearing aids, in or at left and right ears, respectively, each hearing device comprising two microphones (allowing beamformed signals to be generated in each hearing device, individually (based on local microphone signals), and/or binaurally (based on microphone signals from left and right ears)). In other scenarios, the user may wear first and second hearing devices in or at left and right ears, respectively, each hearing device comprising only one microphone (allowing beamformed signals to be generated based on microphone signals from left and right ears). In yet another scenario, the user may wear a single hearing device comprising two or more microphones (allowing beamformed signals to be generated in the hearing device based on (local) microphone signals of the hearing device).
(23) The present application discloses a method for selecting an external microphone signal among multiple microphone signals based on the user's head orientation (or alternatively a target direction identified by the hearing instrument). We assume that the user selects the signal of interest based on the direction of the head (nose). The idea is sketched in FIG. 2.
(24) FIG. 2 shows an embodiment of a method of operating of a hearing system according to the present disclosure, wherein a beamformed signal comprising the target signal provided by one of the hearing instruments of the hearing system is transmitted to the external microphone units for evaluation. The leftmost part of FIG. 2, denoted ‘1)’ illustrates the transmission of a beamformed target enhancing signal obtained at one (HD1, as shown, or both (HD1, HD2)) of the hearing instrument(s) to the external microphone units (1, 2, 3, 4) currently present (and available to the hearing system) in the environment of the user (U). The beamformed signal enhances signals from the front of the user (U) while signals from the back are attenuated. The beamformed signal is illustrated in FIG. 2 by the heart-formed, cardioid-shaped directional pattern. The middle part of FIG. 2, denoted ‘2)’ illustrates an estimation of a similarity coefficient (e.g. correlation) between the beamformed signal and each of the external microphone signals. The coefficients are determined in each of the microphone units (or in devices, which the microphone units form part of) and transmitted back to the hearing instrument (HD1) for comparison. The external microphone unit exhibiting the maximum similarity coefficient is identified in the hearing instrument (HD1). The hearing instrument (HD1) informs each external microphone unit (1, 2, 3, 4), which of the microphone units that has been selected. In bandwidth constrained scenarios, the selected external microphone unit sends its microphone signal to the hearing instrument (HD1), while the other microphone units do not. In bandwidth-rich scenarios, on the other hand, each external microphone unit may send its microphone signal to the hearing instrument (HD1) (e.g. continuously and simultaneously), and a selection of the microphone signal(s) of current interest to the hearing device user may be performed in the hearing instrument; and the hearing instrument may play back the selected microphone signal(s) to the user via loudspeaker(s) of the hearing instrument(s) (e.g. a combination of the microphone signals may be played, e.g. based on probabilities of matching with the beamformed signal of the hearing instrument). The rightmost part of FIG. 2, denoted ‘3)’ illustrates that the external microphone unit (1) having the microphone signal with the highest similarity to the beamformed signal is transmitted to the hearing instrument(s) (HD1, HD2). Thereby a version of the current target sound signal having an improved quality (e.g. signal to noise ratio) is received by the hearing instrument(s) and played for the user (possibly mixed with a (possibly attenuated) signal picked up by hearing aid microphone(s) to give a sense of the acoustic environment of the user).
(25) The beamformed signal may be created using any one of the range of beamforming techniques known in the literature, e.g. MVDR (minimum Variance Distortionless Response) or MWF (Multichannel Wiener Filtering) beamformers, steered in a predefined direction, e.g. straight-ahead of the listener/hearing device user.
(26) As the signal of main interest is assumed to generally be in front of the hearing instrument user (U), the hearing instrument microphones (e.g. (M1F, M1R) in FIG. 1) are combined in such a way that a directional (beamformed) signal is obtained, wherein the front (target) direction is enhanced while noise from other directions is suppressed. This beamformed, target enhanced, signal may be based on microphones ((M1F, M1R) (M2F, M2R)) from either the left hearing instrument (HD1) or the right hearing instrument (HD2), or a combination of microphones from both hearing instruments (M1F, M1R, M2F, M2R) in binaural configurations. The hearing instrument may as well be or comprise a microphone array attached to the head e.g. via a headband or a cap or the like, or built into the frame of a pair of glasses. The beamformed signal may be based on a fixed beamformer or an adaptive beamformer (e.g. where noise is adaptively attenuated). The beamformed signal may have a fixed target direction (such as the front direction) or an adaptive target direction estimated by the hearing instrument. Even though the noise in this beamformed signal has been reduced, one of the external microphones may contain an even more noise-free realization of the target signal. In the exemplary scenario of FIG. 2, the beamformed, target-enhanced, signal is transmitted from the hearing instrument to each of the external microphone units (1, 2, 3, 4), cf. ‘1)’ in FIG. 2. Within each external microphone unit, the similarity between the external microphone signal and the received target enhanced beamformed signal may be estimated. The similarity may e.g. be estimated using one or more of many known similarity measures, e.g. in terms of the correlation between the two signals, e.g. the cross-correlation (e.g. a short-term correlation), a coherence, an average, or . . . . The external microphone signal containing the highest similarity with the received target enhancing signal is transmitted back to the hearing instrument in order to be presented to the listener, cf. ‘3)’ in FIG. 2. In order to compare similarity scores, the external devices may exchange and compare their scores (the information rate exchanged between devices, however, may be very small, as this only needs to happen a few times a second). Each external microphone unit may then compare its local similarity scores and initiate signal transmission to the hearing device(s) according to a selected criterion, e.g. to transmit the signal of a given microphone unit having the largest similarity score, or the signals of those microphone units, e.g. two or three, having the largest scores, e.g. if the score is larger than a minimum threshold. Alternatively, the individual similarity scores of the microphone units may be transmitted back to the hearing instrument (HD1), cf. ‘2)’ in FIG. 2, or to another processing device in communication with the hearing instrument, for comparison there (see e.g. FIG. 3). The ‘comparing device’ may subsequently inform the external microphone units, which of them is(are) (presently) selected for transmitting their audio signal to the hearing device(s).
(27) Alternatively, the similarity scores may not be compared at all (or this option may be a default option, in case of limited bandwidth or link options), and the audio signal of a given microphone unit is transmitted to the hearing device, if its similarity score exceeds a threshold value (e.g. 0.5 for score having values between 0 and 1).
(28) FIG. 2 illustrates a method of operating a hearing system comprising steps 1), 2), 3): 1) Transmit the beamformed target enhancing signal obtained at the hearing instrument to external microphone units: 2) Find the maximum similarity between the beamformed signal and each of the external microphone units. Transmit coefficient back to hearing instrument for comparison; 3) Inform the external microphone units about the decision (who is(are) selected); 4) Transmit the external microphone signal with the highest similarity to the beamformed signal to the hearing instrument(s).
(29) As an alternative or in addition to calculating and transmitting the target enhancing beamformer signal, the hearing instrument may calculate and transmit a target cancelling beamformer signal, as shown in FIG. 3.
(30) FIG. 3 shows an embodiment a method of operating of a hearing system according to the present disclosure, wherein two beamformed signals, one comprising the target signal, the other not comprising the target signal, provided by one of the hearing instruments of the hearing system are transmitted to the external microphone units for evaluation. As an alternative to or in addition to transmitting a beamformed signal wherein the target signal is enhanced (as shown in FIG. 2), a target cancelling beamformer signal may, as shown in FIG. 3, be transmitted to the external microphone(s). The two directional signals are illustrated by the cardioid-shaped patterns pointing towards and away from the target direction in front of the listener (U). Where a target enhancing signal is expected to be highly correlated with a microphone close to the target talker (here talker A, external microphone 1), the target cancelling beamformer (with target absent) is expected to be less correlated to an external microphone signal mainly containing the target talker. The similarity measure may thus be measured as a ratio between the target enhancing beamformer signal (y.sub.tgt) correlated with the external microphone signal (here x.sub.1) and the target cancelling beamformer signal (y.sub.tgtcncl) correlated with external microphone signal (x.sub.1). We may thus base our similarity measure of the n'th external microphone unit as the ratio between two correlation coefficients. i.e.
(31)
where ρ(x.sub.n, y.sub.tgt) is the correlation coefficient (the maximum correlation value, possibly averaged across time) between the n'th external microphone signal x.sub.n and the target enhancing beamformer signal y.sub.tgt and similarly, ρ(x.sub.n, y.sub.tgtcncl) is the correlation between the n'th external microphone signal and the target cancelling beamformer signal y.sub.tgtcncl. In an alternative embodiment, the similarity measure sim is dependent only on the correlation p of the external microphone signal with the target enhancing beamformer signal ρ(x.sub.n, y.sub.tgt) or only with the target cancelling beamformer signal ρ(x.sub.n, y.sub.tgtcncl).
(32) FIG. 3 illustrates a method of operating a hearing system comprising steps 1), 2), 3): 1) Transmit the beamformed target enhancing signal and the target cancelling beamformed signal obtained at the hearing instrument to external microphone units: 2) Find the maximum similarity based on the received target enhancing signal and the received target cancelling signal for each of the external microphones. Transmit coefficient back to hearing instrument (or other processing device) for comparison; 3) Inform the external microphone units about the decision (who is(are) selected); 4) Transmit the external microphone with the highest similarity to the beamformed signal to the hearing instrument(s).
(33) Different examples of possible implementations of the similarity measure are illustrated in FIG. 4 and FIG. 5.
(34) FIG. 4 shows a first exemplary implementation of the similarity measure. Given the m'th time frame of the different input signals (x.sub.n, y.sub.tgt and y.sub.tgtcncl), the cross-correlation is calculated (cf. units xcorrr). It is important that the frame length T.sub.F of the signals is sufficiently long in order to take different possible latencies of the input signals into account as the latency of each of the external microphones is not necessarily known. The frame length T.sub.F may e.g. be 50 milliseconds. The maximum cross-correlation value is found (cf. units abs and max) and possibly low-pass filtered (cf. unit LP) (and possibly down-sampled) before the ratio sim.sub.n(m) between the maximum cross-correlation values is calculated (cf. unit ÷) for the m'th signal frame, where m is a (time) frame index.
(35) FIG. 5 shows a second exemplary implementation of the similarity measure. The implementation of the similarity measure of FIG. 5 is in the frequency domain. The m'th frame of the time domain signals (x.sub.n, y.sub.tgt and y.sub.tgtcncl) is converted into the frequency domain, e.g. by a short-time Fourier transform implemented by use of the fast Fourier transform (cf. respective analysis filter bank units (FBA)) providing respective frequency domain (sub-band) signals Y.sub.tgt(m,k), X.sub.n(m,k) and Y.sub.tgtcncl(m,k), where m and k are time and frequency indices, respectively. It is important that the frame length of the signals is sufficiently long in order to take different possible latency of the input signals into account. The frame length may e.g. be 50 milliseconds. In each frequency channel (defined by frequency index k), the magnitude (cf. unit abs) or squared magnitude (cf. unit |abs|.sup.2) of the products (X.sub.n*Y.sub.tgt and X.sub.n*Y.sub.tgtcncl, or the products |x.sub.n|.Math.|y.sub.tgt| and |x.sub.n|.Math.|y.sub.tgtcncl|, cf. multiplication units ‘X’) are calculated and possibly low-pass (LP) filtered (cf. units LP), and possibly followed by a down-sampling, before the ratio sim.sub.n(m) between the values is calculated (cf unit ÷). Alternatively, the similarity measure may be based on ρ(x.sub.n, y.sub.tgt) or ρ(x.sub.n, y.sub.tgtcncl). The cross correlation may e.g. be calculated in terms of Pearson's correlation coefficient.
(36) Pearson's (sample) correlation coefficient may be written as
(37)
Where represent the two signals x and y that are to be correlated and x.sub.i and y.sub.i are specific samples thereof (at time index i), μ.sub.x, μ.sub.y are average values of x and y and N is a time range (number of time frames considered). Samples x.sub.i and y.sub.i (and thus ρ) may be frequency dependent (e.g. via frequency index k). The time range represented by N is dependent on the dynamics of the acoustic environment. Preferably N is selected as a compromise between stability of the correlation measure (N should be sufficiently long to not react to fast changing, temporary situations, and sufficiently short to not delay adaptation to (sudden but) more stable changes to the acoustic environment). As an alternative to the sum over N samples a recursive average could be calculated using first order IIR filters.
(38) In addition to (or instead of) measuring the similarity using correlation between the audio signals, other similarity measures may be used. For example, the estimated SNR of the target enhanced beamformer signal may be compared to the estimated SNR of the external microphones. In an embodiment, only if the SNR of the external microphone signal (X.sub.n) is higher than the SNR of the beamformed signal (Y.sub.tgt) of the hearing device, the external microphone signal (X.sub.n) is transmitted to (or received by) the hearing device and presented to the listener.
(39) In the case of one hearing instrument on each ear (cf. e.g. HD1, HD2 in FIG. 1-3), a target enhanced signal may be available from the local processing at each hearing instrument. In order to save communication bandwidth, it is preferable that only one of the target enhanced signals is transmitted. One way of selecting which of the target enhanced signals to be transmitted is to estimate the local signal to noise ratio at each hearing instrument. Such a signal to noise ratio may e.g. be based on the modulation depth of the audio signals. Based on a comparison between the estimated signal-to-noise ratios, preferably the target-enhanced signal containing the highest estimated signal to noise ratio should be transmitted to the external microphone units (cf. e.g. 1, 2, 3, 4 in FIG. 1-3).
(40) An external microphone unit may consist of one or more microphones (e.g. a microphone array). The external microphone signal may be a directional signal, or an omnidirectional signal obtained by a combination of the microphones within the external microphone unit. The external microphone unit may be or form part of a mobile phone such as a smartphone. The external microphone unit may run an application capable of calculating the necessary steps in order to determine if the external microphone signal shall be presented to the listener. Such a step may be finding the similarity between the external microphone signal and the received signals from the hearing instrument.
(41) In order to save power and reduce the amount of bandwidth needed for transmitting the signal from the hearing instrument, the transmitted microphone signal may be low-pass filtered and down-sampled, e.g. to a sample rate of 1000 Hz or 2000 Hz or 4000 Hz or 8000 Hz. Alternatively, the signals may be transmitted in frequency bands. In an embodiment, the signal is transformed into the frequency domain before it is transmitted. In one embodiment only the amplitude (magnitude) response of the signal is transmitted such that the similarity measure is based on comparison between amplitude responses. In one embodiment, temporal envelopes extracted from selected frequency sub-bands are transmitted—the advantage of this is that the envelope signals can be down-sampled significantly, in order to reduce the information needed to be transmitted. Similarity measures based on envelope fidelity may then be used at the wireless device (microphone unit).
(42) In an embodiment, the received external microphone signal is ‘binauralized’ based on the estimated direction of arrival (DOA) before presented to the listener (e.g. by applying appropriate head related transfer functions (HRTF) for the estimated DOA to the signal received from the external microphone unit before presenting the signals at the respective left and right hearing instruments, see e.g. US2013094683A1).
(43) An advantage of the present invention is that not all microphone signals need to be transmitted/exchanged.
(44) In the shown preferred embodiment some calculations are performed in the external microphone units while other calculations take place in the hearing instrument. It is obvious that the calculations as well may take place in other units. E.g., all calculations may take place in the hearing instrument, as illustrated in FIG. 6.
(45) FIG. 6 shows an embodiment a method of operating of a hearing system according to the present disclosure, wherein, contrary to FIG. 2 or 3, all calculations may take place in the user's hearing instrument. This requires that all external microphone signals are (at least partly) transmitted to the hearing instrument 1). The similarity to each external microphone signal is calculated in the hearing instrument 2), and the microphone signal with the highest similarity (microphone 2) is presented to the listener 3). In case a signal from a target cancelling beamformer of the hearing instrument is used for comparison with the respective audio signals of the external microphone units, the signal exhibiting the smallest (absolute) correlation (ρ(x.sub.n, y.sub.tgtcncl)) would be selected for presentation to the hearing instrument user. This may be advantageous, as the external microphone signals may serve as noisy reference signals even though they are not directly presented to the listener. In an embodiment only a low- or band-pass filtered external audio signal is transmitted to the hearing instrument for similarity comparison. Alternatively, not all time frames of the external microphone signals are transmitted. Only the selected external microphone signal to be presented to the listener are required to be transmitted with full framerate and bandwidth.
(46) In another embodiment all similarity measures are exchanged between all external microphone units.
(47) In one embodiment, the hearing instrument contains an own voice detector. In case of a detected own voice signal, the local microphones should be presented to the listener (e.g. the hearing instrument user) rather than any external microphone signal.
(48) Switching between different external microphones or switching between the hearing instrument microphones and the external microphones should not be noticed by the listener. Preferably, the switching between different microphones may happen during speech pauses.
(49) The selection of a particular external microphone unit as the source of the target sound signal may change over time as e.g. the user changes head direction, see FIG. 7. In an embodiment the similarity measure is calculated continuously. e.g. based on transmitted audio signals with a transmission rate of e.g. 50 times per second, also other transmission rates may be utilized, e.g. 100 times per second or 10 times per second or once per second. The transmission rate of the different external microphones may be different. In an embodiment the transmission/calculation rate is increased if a head movement is detected.
(50) FIG. 7 shows an example of how the user by his head is able to select a talker of interest. In the left part of FIG. 7 (denoted ‘1)’), the listener is looking towards the direction of talker A, while talker B is talking at the same time. In this situation, as the target enhancing beamformer of the (here left) hearing instrument (HD1) mainly contains sound from talker A, and the target cancelling beamformer mainly attenuates talker A, the similarity measure will indicate that the signals of microphone 1 should be presented to the listener. In the right part of FIG. 7 (denoted ‘2)’), the listener (U) has turned his head towards the conversation between talker B and C. In this case the target enhancing beamformer mainly contains talker C (and B), and the target cancelling beamformer attenuates talker C (and B). In this case, the similarity measure will indicate that the signal from microphone 4 should be presented to the listener.
(51) In an embodiment, each of (or at least one of the microphone units comprise a voice activity detector, providing an indication of whether or not, or with what probability, a current signal picked up by the microphone(s) of the microphone unit contains speech. Thereby calculation of similarity measures (coefficients) in a given microphone unit may be restricted to times where speech is detected by the voice activity detector of the microphone unit. If no speech is detected, the similarity measure may be set to a value ‘0’ (indicating no or low similarity).
(52) FIG. 8 shows an embodiment of a hearing device according to the present disclosure. The hearing device (HD), e.g. a hearing aid, may e.g. be adapted for being worn by (and/or implanted in) a user. The hearing device comprises an input unit (IU) comprising a multitude of microphones (here two microphones (M.sub.1, M.sub.2)). Each microphone (M.sub.1, M.sub.2) provides an electric input signal (IN.sub.1, IN.sub.2, respectively) representative of the sound field around the user wearing the hearing device. The input unit (IU) further comprises respective analysis filter banks (FBA) for providing the electric input signals in a time-frequency representation (as frequency sub-band signals (IN.sub.1(k), IN.sub.2(k), k=1, . . . , K). The hearing device (HD) further comprises a beamformer filter (BFU) (or directional system, cf. DIR in FIG. 10) providing a beamformed signal Y.sub.BF(k) from the multitude of electric input signals (IN.sub.1(k), IN.sub.2(k)). The hearing device further comprises a selector-mixer (SEL/MIX) selecting an appropriate wirelessly received signal ACx′(k) from an external microphone unit according to the current interest of the user. The hearing device (HD) comprises a wireless transceiver (ANT, Rx/Tx) for wirelessly receiving (and demodulating, etc.) information and/or audio data (ACx) from other devices, e.g. audio transmitters. The appropriate wirelessly received signal ACx′(k) may e.g. be determined by the selection processor (SELP), e.g. based on a correlation measure indicative of a correlation between the beamformed signal Y.sub.BF(k) and the wirelessly received signal ACx. The selected wirelessly received signal ACx′(k) may e.g. be mixed (in the selector-mixer (SEL/MIX)) with the beamformed signal Y.sub.BF(k) to provide a resulting mixed signal SA(k), e.g. controlled by selection control signal SCT from the selection processor (SELP). Before mixing, appropriate alignment (time delay, and/or gain (attenuation or amplification)) may be applied to the respective input audio signals (e.g. based on a correlation measurement). The hearing device (HD) further comprises a signal processor (SPU) configured to further adapt the signal SA(k) to the needs of a user, e.g. to apply a frequency and level dependent gain (amplification or attenuation) according to the user's hearing impairment (e.g. based on data representative of a hearing threshold versus frequency. e.g. an audiogram). The signal processor (SPU) provides a processed output signal OUT(k). The hearing device (HD) further comprises an output unit (OU) configured to provide stimuli perceivable by the user as sound. The output unit (OU) of the embodiment of a hearing device of FIG. 8 comprises a synthesis filter bank (FBS) for converting the frequency sub-band signals OUT(k) to a signal OUT in the time domain, and a loudspeaker (SPK) for converting the processed output signal OUT to acoustic stimuli for presentation to the user. The output unit (OU) may comprise a digital to analogue converter as the case may be. Likewise, on the input side, appropriate analogue to digital converters may be applied.
(53) The wireless transceiver (ANT, Rx/Tx) may be configured to (modulate, encode, etc., and) wirelessly transmit information and/or audio data (HDx) from the hearing device to other devices, e.g. audio transmitters (e.g. microphone units) or associated processing units, e.g. for evaluating a degree of similarity between an audio signal picked up by the hearing device and an audio signal picked up by an external audio transmitter, e.g. a microphone unit.
(54) The selection processor (SELP) is configured to compare the beamformed signal Y.sub.BF with respective audio signals from the currently available audio transmitters (or with bandlimited, or down-sampled versions thereof). The selection processor (SELP) is configured to select the one or more of the currently available audio signals according to a selection criterion, e.g. the one(s) exhibiting the highest correlation measure(s), and to issue a transmission request to the audio transmitter(s) in question, and to subsequently receive the audio signal(s) of current interest to the user in the hearing device and presenting the audio signal(s) to the user, possibly as a mixture with an audio signal picked up by a microphone or microphones of the hearing device (e.g. the beamformed signal, e.g. appropriately aligned in time with the wirelessly received signal(s) to avoid artifacts/distortion).
(55) The hearing device of FIG. 8 may e.g. be used in connection with a multitude of external, spatially separated audio transmitters. e.g. microphone units (cf. e.g. units 1, 2, 3, 4, in FIG. 1-3, 6, 7). The audio transmitters, e.g. microphone units, are individual devices or form part of respective separate electronic devices, e.g. communication devices (e.g. smartphones), or form part of another hearing device, each being configured to pick up sound from a sound field surrounding the hearing device (HD) (but preferably providing sound from one or more sound sources in a better quality than what is received acoustically by the microphones of the hearing device (HD)).
(56) One or more of the audio transmitters may be configured to transmit sound that is simultaneously provided as acoustic signals, but which is not necessarily representative of sound from the immediate environment of the user. Such audio transmitters may e.g. transmit sound from a TV or other entertainment device, or any other device comprising a loudspeaker and an audio transmitter.
(57) The hearing system comprising the hearing device (HD) and the audio transmitters are configured to allow wireless communication, including audio communication, between the hearing device and the audio transmitters (e.g. external microphone units), at least from the audio transmitters (e.g. microphone units) to the hearing device (HD), e.g. a hearing aid.
(58) FIG. 9A illustrates an embodiment of a hearing system, e.g. a binaural hearing aid system, according to the present disclosure. The hearing system comprises left and right hearing devices in communication with an auxiliary device, e.g. a remote control device, e.g. a communication device, such as a cellular telephone or similar device capable of establishing a communication link to one or both of the left and right hearing devices. FIG. 9B illustrates an auxiliary device configured to execute an application program (APP) implementing a user interface of the hearing device or system from which a mode of operation for selecting of wireless reception of sound from an active sound source can be selected and/or configured.
(59) FIG. 9A, 9B together illustrate an application scenario comprising an embodiment of a binaural hearing aid system comprising first (left) and second (right) hearing devices (HD1, HD2) and an auxiliary device (AD) according to the present disclosure. The auxiliary device (AD) comprises a cellular telephone, e.g. a SmartPhone. In the embodiment of FIG. 9A, the hearing devices and the auxiliary device are configured to establish wireless links (WL-RF) between them, e.g. in the form of digital transmission links according to the Bluetooth standard (e.g. Bluetooth Low Energy, or equivalent technology). The links may alternatively be implemented in any other convenient wireless and/or wired manner, and according to any appropriate modulation type or transmission standard, possibly different for different audio sources. The auxiliary device (e.g. a SmartPhone) of FIG. 9A, 9B comprises a user interface (UI) providing the function of a remote control of the hearing aid system, e.g. for changing program or mode of operation or operating parameters (e.g. volume) in the hearing device(s), etc. The user interface (UI) of FIG. 9B illustrates an APP (denoted ‘Select audio source’ (‘Configure wireless reception’)) for selecting a mode of operation of the hearing system or device where a currently active sound source is to be selected, either by directing the nose towards the sound source (option ‘Choose with nose’), or by using eye gaze (‘Choose with eye gaze’), or by manually selecting the sound source of interest (‘Choose manually’) via the graphical user interface (see sketch with user (U) and geometrical distribution of active sound sources (S1-S4) in the lower part of the screen of FIG. 9B). In the screen of FIG. 9B, the ‘Choose with eye gaze’ mode of operation has been selected as indicated by the left solid ‘tick-box’ and the bold face indication ‘Choose with eye gaze’ (and in the sketch by Sound source S2 being grey shaded selected by the user's eye gaze towards source S2). The control of functionality in a hearing device using eye gaze is e.g. discussed in US20170180882A1.
(60) In an embodiment, at least some of the calculations related to source selection (e.g. detection of which of the active sound sources correlate best with a current (assumed) intention of the user; i.e. with the (possibly beamformed) sound signal received by the microphones of the hearing devices worn by the user) are performed in the auxiliary device. In another embodiment, the calculations are fully or partially performed in the left and/or right hearing devices. In the latter case the system may be configured to exchange the data between the auxiliary device and the hearing device(s). The hearing device (HD1, HD2) are shown in FIG. 9A as devices mounted at the ear (behind the ear) of a user (U). Other styles may be used, e.g. located completely in the ear (e.g. in the ear canal), fully or partly implanted in the head, etc. As indicated in FIG. 9A, each of the hearing instruments may comprise a wireless transceiver to establish an interaural wireless link (IA-WL) between the hearing devices, e.g. based on inductive communication or RF communication (e.g. Bluetooth technology). Each of the hearing devices further comprises a transceiver for establishing a wireless link (WL-RF, e.g. based on radiated fields (RF)) to the auxiliary device (AD), at least for receiving and/or transmitting signals, e.g. control signals, e.g. information signals, e.g. correlation estimates, e.g. including audio signals. The transceivers are indicated by RF-IA-Rx/Tx-1 and RF-IA-Rx/Tx-2 in the right (HD2) and left (HD1) hearing devices, respectively.
(61) FIG. 10 shows an embodiment of a hearing aid or a hearing aid system according to the present disclosure. The embodiment of FIG. 10 is similar to the embodiment of FIG. 8. It comprises the same functional elements as the embodiment of FIG. 8, but the processing units of the forward path from input unit (IU) to the output unit (OU) comprise combination units (‘+’, ‘X’) in the forward path itself to combine signals (‘+’) or to apply appropriate gains to signals (‘X’) AND respective processing units (DIR, COMP) in parallel with the forward path to determine appropriate gains applied to signals of the forward path by the multiplication units (‘X’). The difference reflects different appropriate implementations, which may depend on the application in question.
(62) The selection processor (SELP) of the embodiment of FIG. 10 receives the beamformed signal Y.sub.BF (representative of a signal of current interest to the user as picked up the microphones (M.sub.1, M.sub.2) of the hearing device and spatially filtered by the directional system (DIR, see equivalent BFU in FIG. 8). The selection processor (SELP) further receives the wirelessly received signal ACx on the AUX-channel. The two signals may both be provided to the selection processor as frequency sub-band signals (indicated by index k, k=1, . . . , K; K may e.g. be in the range from 2 to 128). However, the wirelessly received signal ACx may e.g. be received (and/or analysed) in a fewer number of frequency channels than K (of the forward path), and/or down-sampled to minimize the processing power during identification of the sound source of current interest to the user. The down-sampling and or reduction to fewer channels for comparison with the beamformed signal of the forward path may e.g. be performed in the selection processor (SELPa). A transmission request to one or more of the currently active audio transmitters (cf. e.g. microphone units 1, 2, 3, 4 in FIG. 1, 2, 3, 6, 7) around the hearing device may be issued by the selection processor (SELPa) and transmitted by the transmitter (Tx) to the audio transmitters. A scanning process may thus be initiated by the selection processor (SELPa) and, when signals from all available (relevant) transmitters have been compared with the beamformed signal (e.g. using a correlation measure), the signal that is determined to be of the user's current interest (largest correlation measure) can be requested from the audio transmitter in question (and e.g. processed in full audio quality by the hearing device). When the signal of current interest to the user has been decided on, e.g. indicated by the control signal SCT′ from selection processor part SELPa to SELPb, the beamformed signal Y.sub.BF and the wirelessly received signal ACx are analysed by the selection processor (SELPb) and an appropriate mutual weighting of the two signals (and possible alignment and/or frequency and level dependent shaping of one or both) may be determined and applied to the signals in the selection processor and/or via respective multiplication units ‘(X’). A combination unit (‘+’) sums the two weighted signals and provides a resulting output signal OUT(k), which is fed to the output unit for presentation to a user as described in connection with FIG. 8. In an embodiment, none of the wirelessly received signals ACx are selected for presentation to the user. This can e.g. be of interest in situations, where the signal picked up the input transducers of the hearing device (e.g. the beamformed signal Y.sub.BF) is of a higher quality (e.g. SNR) than any of the wirelessly received signals from the audio transmitters. In such case, only the locally picked up signal, e.g. Y.sub.BF, may be presented to the user. The hearing device (e.g. the selection processor) may comprise appropriate memory units to facilitate alignment of signals and other processes of the hearing device.
(63) The process for determining a sound source of current interest to the user may be to configure the system to provide access to all external microphone signals at the same time. By constantly analysing these signals a decision can be made on which signal(s) is(are) most relevant to present to the user. The decision can be based on a comparison of the levels of the signals, their modulation characteristics, an estimate of diffuseness or reverberation and/or the level of broadband background noise in each channel. The analysis can be done taking both the microphone signals, and the wirelessly received signals into account. For example, the target source signal which is most energetic in the microphone signal may be determined by using individual, wirelessly received, target signals when analysing the microphone signals. The most energetic target signal often originates from the target speaker which is closest to the hearing aid user (assuming here that physical proximity correlates with relevance). In an embodiment, an appropriate ‘soft mixture’ of signals is presented to the user, e.g. based on a linear combination of the available input signals. The weights of the linear combination may e.g. be dependent on the degree of similarity of the individual signals from the external microphone units with a signal received by the microphone(s) of the hearing device.
(64) The two illustrations in the top left corner of FIG. 10 is intended to indicate that the two input transducers IT1 and IT2 may be located at the same ear or at opposite ears of the user (U). In case the input transducers are located at opposite ears ((right illustration) e.g. in contralateral hearing aids of a binaural hearing aid system), the input transducer, e.g. IT2, representing the input transducer of an opposite ear comprises appropriate receiver circuitry for wirelessly receiving the signal (e.g. a microphone signal) from the other hearing aid. In such case appropriate circuitry for compensating for processing delay of the transmitted signal may be included, e.g. in the analysis filter bank or in the directional system.
(65) The hearing device (HD) comprises a wireless receiver (Rx) for receiving information or audio data from another device via an AUX channel. The other (transmitting) device may e.g. be an external audio transmitter, e.g. a microphone unit or a processing unit, in the environment of the hearing device. External audio transmitters, e.g. microphone units, may connect to the aux channel either through digital (e.g. Bluetooth or the like) or analogue (e.g. FM) transmission. The wireless receiver (Rx) (and the input transducers (IT1, IT2)) may comprise analogue to digital conversion capability as appropriate.
(66) The hearing devices shown in FIGS. 8 and 10 may e.g. be used in a scenario, where several microphone units (here three, MU1, MU2, MU3) share the same transmission channel, i.e. only one signal can be input to the hearing devices (HD1, HD2) at a time.
(67) In such case it should be agreed among the active microphone units which one is to transmit/receive at a given point in time, e.g. by a scanning and correlation procedure as described above, e.g. where a user's nose or eye gaze (look direction) determines a current sound source of interest. This situation is shown in FIG. 11, where at time A (left part of FIG. 11), the user (U) looks at talker T1 (cf. dotted arrow denoted LD1 indicating a look direction of the user towards T1) and receives (after an appropriate scanning procedure) a wireless signal picked up by a microphone unit (MU1) worn by talker T1, and at time B (right part of FIG. 11), the user (U) looks at talker T2 (cf. dotted arrow denoted LD2) and receives (after an appropriate scanning procedure) a wireless signal picked up by microphone unit (MU2) worn by talker T2.
(68) One way to implement a scenario as shown in FIG. 11 is to, once in a while, exchange metadata about each microphone. Such metadata could e.g. be the sound pressure level at each microphone or it could also be information such as the amount of modulation (e.g. provided by a voice activity detector) in each microphone signal or a bandlimited or down-sampled version of each microphone signal, or a combination of such measures. This metadata only occupies the transmission channel for a short while. The received data can be compared, either amongst the microphones or at the hearing devices, and based on the comparison, it can be decided from which microphone to send/receive the audio data. This of course requires that each microphone unit is able to transmit as well as to receive signals. Hysteresis may be built into the transmission decision in order to avoid that the audio data switch (unintentionally, too fast) between the microphone units. This processing scheme is illustrated in FIG. 12.
(69) FIG. 12 shows an example of the scenario of FIG. 11 where several remote microphone units have to share the same communication channel. Metadata (which only occupies a small amount of time compared to audio data) are exchanged between all the microphones in order to decide which of the microphone audio signals should be transmitted to the hearing instruments at a given point in time. In the example above, it is decided to transmit audio data from microphone unit 1 (MU1) in the first and second audio data blocks. For the third data block it is decided to transmit the audio data from the second microphone unit (MU2).
(70) In general, the decision of a degree of similarity between signals received by the hearing device and picked up and/or transmitted by the audio transmitters may be based on microphone signals at one (monaural) or both (binaural) ears of the user. Spatial ‘binauralization’ is e.g. discussed in patent applications by Mojtaba et al. (e.g. US20180262849A1, or EP3285500A1).
(71) 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.
(72) 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,” w % ben 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 is not limited to the exact order stated herein, unless expressly stated otherwise.
(73) 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.
(74) The claims are not intended to be limited to the aspects shown herein, but is 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
(75) US20170180882A1 (Oticon) 22 Jun. 2017 US20180262849A1 (Oticon) 13 Sep. 2018 EP3285500A1 (Oticon) 21 Feb. 2018 US2013094683A1 (Oticon) 18 Apr. 2013
(76) Accordingly, the scope should be judged in terms of the claims that follow.
