Binaural hearing aid system providing a beamforming signal output and comprising an asymmetric valve state

Abstract

The present disclosure relates to a binaural hearing aid system comprising hearing aids for placement at, or in, a user's left and right ear, the hearing aids each comprising a microphone arrangement, a wireless communications unit, a receiver, and a sound channel with a valve, which is movable from an open state to an closed state and from a closed state to an open state. The binaural hearing aid system further comprises a signal processing arrangement adapted for generating a beamformed signal based on microphone signals supplied by either or both of the microphone arrangement(s) and for applying the beamformed signal to either or both of the receiver(s), and a valve control arrangement configured to asymmetrically control the valves in each hearing aid by moving the valves into positions wherein one of the valves is opened more than the other.

Claims

1. A binaural hearing aid system comprising: a first hearing aid for placement at, or in, a first ear of a user, the first hearing aid comprising a first microphone arrangement, a first wireless communication unit, a first receiver, and a first sound channel comprising a first valve; a second hearing aid for placement at, or in, a second ear of the user, the second hearing aid comprising a second microphone arrangement, a second wireless communication unit, and a second sound channel comprising a second valve; a signal processing arrangement configured to generate a beamformed signal and an omnidirectional signal, wherein the signal processing arrangement is configured to apply the beamformed signal to one of the first receiver in the first hearing aid or the second receiver in the second hearing aid, and to apply the omnidirectional signal to the other one of the first receiver in the first hearing aid or the second receiver in the second hearing aid; and a valve control arrangement configured to asymmetrically control the first and second valves by moving the first valve and/or the second valve so that one of the first valve or the second valve, which is in one of the first hearing aid or the second hearing aid in which the omnidirectional signal is applied, is opened more than the other one of the first valve or the second valve, which is in the other one of the first hearing aid or the second hearing aid in which the beamformed signal is applied.

2. The binaural hearing aid system according to claim 1, wherein the omnidirectional signal is a bilateral omnidirectional signal.

3. The binaural hearing aid system according to claim 2, wherein one of the first hearing aid or the second hearing aid in which the beamformed signal is applied is configured to provision a first microphone signal; wherein the other one of the first hearing aid or the second hearing aid in which the omnidirectional signal is applied is configured to provision a second microphone signal; wherein the binaural hearing aid system is configured to time delay the first microphone signal relative to the second microphone signal; and wherein the bilateral omnidirectional signal is based on a mixing of the time-delayed first microphone signal and the second microphone signal.

4. The binaural hearing aid system according to claim 1, wherein the beamformed signal is based at least on two or more microphone signals supplied by one of the first microphone arrangement or the second microphone arrangement comprised in one of the first hearing aid or the second hearing aid in which the beamformed signal is applied.

5. The binaural hearing aid system according to claim 1, further comprising an omnidirectional processing arrangement, which comprises a first omnidirectional signal processor and a second omnidirectional signal processor; wherein the first omnidirectional signal processor is a part of the first hearing aid or the second hearing aid in which the beamformed signal is applied; and wherein the second omnidirectional signal processor is a part of the first hearing aid or the second hearing aid in which the omnidirectional signal is applied.

6. The binaural hearing aid system according to claim 5, wherein the first omnidirectional signal processor is configured to: generate a first monaural directional signal; transmit, through a wired or wireless communication link, the first monaural directional signal to one of the first hearing aid or the second hearing aid in which the omnidirectional signal is applied.

7. The binaural hearing aid system according to claim 6, wherein the second omnidirectional signal processor is configured to: receive the first monaural directional signal; generate a second monaural directional signal; and mix the first and second monaural directional signals in a fixed or adjustable ratio to generate a bilateral omnidirectional signal.

8. The binaural hearing aid system according to claim 5, wherein the signal processing arrangement and the omnidirectional processing arrangement are comprised in a same processing unit.

9. The binaural hearing aid system according to claim 1, wherein the signal processing arrangement comprises a first signal processing unit housed in the first hearing aid and a second signal processing unit housed in the second hearing aid.

10. The binaural hearing aid system according to claim 1, wherein the valve control arrangement is configured to fully close the first valve when the second valve is opened, and to fully close the second valve when the first valve is opened.

11. The binaural hearing aid system according to claim 1, wherein the valve control arrangement is configured to open one of the first valve or the second valve in response to an omnidirectional signal being applied in a corresponding one of the first hearing aid or the second hearing aid.

12. The binaural hearing aid system according to claim 1, wherein the valve control arrangement is configured to close one of the first valve or the second valve in response to a beamformed signal being applied in a corresponding one of the first hearing aid or the second hearing aid.

13. The binaural hearing aid system according to claim 1, wherein the first valve is configured to open at least partially or close at least partially in response to a first valve control signal, and wherein the second valve is configured to open at least partially or close at least partially in response to a second valve control signal.

14. The binaural hearing aid system according to claim 1, wherein the first sound channel is located in a part of the first hearing aid which is configured for placement in a first ear canal of the user, and wherein the second sound channel is located in a part of the second hearing aid which is configured for placement in a second ear canal of the user.

15. The binaural hearing aid system according to claim 1, wherein the valve control arrangement is configured to asymmetrically control the first and second valves in response to the binaural hearing aid system entering a conversation mode.

16. The binaural hearing aid system according to claim 15, wherein the binaural hearing aid system is configured to enter the conversation mode upon request by the user.

17. The binaural hearing aid system according to claim 15, wherein the binaural hearing aid system is configured to enter the conversation mode in response to a signal strength(s) of microphone signal(s) from the first microphone arrangement and/or the second microphone arrangement crossing a noise threshold.

18. The binaural hearing aid system according to claim 1, wherein the signal processing arrangement is configured to generate the beamformed signal based on microphone signals supplied by the first microphone arrangement and/or the second microphone arrangement.

19. The binaural hearing aid system according to claim 1, wherein the signal processing arrangement is configured to generate the omnidirectional signal based on microphone signals supplied by the first microphone arrangement and/or the second microphone arrangement.

20. A method of providing a beamformed signal for a first ear of a hearing aid user and a bilateral omnidirectional signal for a second ear of the hearing aid user, the method comprising: generating, by a beamforming arrangement, a bilaterally or monaurally beamformed signal based at least on two or more microphone signals supplied by a first microphone arrangement of a first hearing aid in the first ear of the hearing aid user; converting the bilaterally or monaurally beamformed signal into a corresponding audible beamformed signal for the first ear of the hearing aid user; generating a first monaural directional signal based on one or more microphone signals provided by the first microphone arrangement of the first hearing aid in the first ear of the hearing aid user; generating a second monaural directional signal based on one or more microphone signals provided by a second microphone arrangement of a second hearing aid in the second ear of the hearing aid user; mixing the first and second monaural directional signals in a fixed or adjustable ratio to generate the bilateral omnidirectional signal; converting the bilateral omnidirectional signal into a corresponding audible omnidirectional signal for the second ear of the hearing aid user; closing, by a valve control arrangement, a first valve in the first hearing aid in the first ear of the hearing aid user; and opening a second valve in the second hearing aid in the second ear of the hearing aid user.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following exemplary embodiments are described in more detail with reference to the appended drawings, wherein:

(2) FIG. 1 schematically illustrates a binaural hearing aid system comprising a left ear hearing aid and a right ear hearing aid connected via a bidirectional wireless data communication channel in accordance with exemplary embodiments,

(3) FIG. 2 shows a schematic block diagram of a left hearing aid of the binaural hearing aid system in accordance with an embodiment,

(4) FIG. 3 shows a schematic block diagram of a right hearing aid of the binaural hearing aid system in accordance with an embodiment,

(5) FIG. 4 is a schematic illustration of a hearing impaired individual fitted with a binaural hearing aid system in accordance with exemplary embodiments,

(6) FIG. 5 is a schematic illustration of the properties of the bilateral beamforming signal and the bilateral omnidirectional signal generated by exemplary embodiments of the binaural hearing aid system,

(7) FIG. 6 shows a set of measured polar patterns of the bilateral omnidirectional microphone signal based on the first and second monaural directional signals at test frequencies 1, 2 and 4 kHz with the second hearing aid fitted on KEMAR's right ear, and

(8) FIG. 7 shows a set of polar patterns, measured at 1 kHz, 2 kHz and 4 kHz, of the bilateral beamforming signal generated by an exemplary embodiment of the bilateral beamformer of a hearing aid in the bilateral hearing aid system;

DETAILED DESCRIPTION OF EMBODIMENTS

(9) In the following various exemplary embodiments of the present binaural hearing aid system are described with reference to the appended drawings. It should be noted that the figures may or may not be drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. Like elements will, thus, not necessarily be described in detail with respect to each figure. It should also be noted that the figures are only intended to facilitate the description of the embodiments. They are not intended as an exhaustive description of the invention or as a limitation on the scope of the invention. In addition, an illustrated embodiment needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated, or if not so explicitly described.

(10) FIG. 1 schematically illustrates a binaural hearing aid system 1 comprising a left ear hearing aid 10L and a right ear hearing aid 10R each of which hearing aids 10L, 10R comprises a wireless communication unit 14L, 14R for connection to the other hearing aid. In the present embodiment, the left ear and right ear hearing aids 10L, 10R are connected to each other via a bidirectional wireless, or possibly wired, data communication connection or link 12, which supports real-time streaming of digitized microphone signals. A unique ID may be associated with each of the left ear and right ear hearing aids 10L, 10R. Each of the illustrated wireless communication units 14L, 14R of the binaural hearing aid system 1 may be configured to operate in the 2.4 GHz industrial scientific medical (ISM) band and may be compliant with a Bluetooth LE standard. Alternatively, each of the illustrated wireless communication units 14L, 14R may comprise magnetic coil antennas 16L, 16R and based on near-field magnetic coupling such as the NMFI operating in the frequency region between 10 and 20 MHz.

(11) The left hearing aid 10L and the right hearing aid 10R may be substantially identical in some embodiments of the present hearing aid system except for the above-described unique ID such that the following description of the features, components and signal processing functions of the left hearing aid 10L also applies to the right hearing aid 10R unless otherwise noted. The left hearing aid 10L may comprise a ZnO.sub.2 battery (not shown) or a rechargeable battery that is connected for supplying power to the hearing aid circuit 18L. The left hearing aid 10L comprises a microphone arrangement 20L that preferably at least comprises first, and possibly second, omnidirectional microphones as discussed in additional detail below.

(12) The left hearing aid 10L further comprises a sound channel 26L, which is configured such that ambient sound can travel, via the sound channel 26L, from outside the hearing aid 10L to the ear canal of the hearing aid user. Depending on the type of hearing aid 10L, the sound channel may be located in the part of the hearing aid 10L, which resides in the ear canal of the user during use. Within the sound channel 26L a valve 28L is movable from an open state to a closed state and from a closed state to an open state. When in an open state the valve 28L may be partially or fully open. A closed valve 28L will act to hinder ambient sound from travelling to the ear canal of the hearing aid user, while an open valve 28L will allow ambient sound to travel to the ear canal of the hearing aid user. The more open a valve 28L is, the easier it will be for ambient sound to travel in the sound channel 26L.

(13) The state of the valve 28L is controlled by means of a valve control signal, which is generated by a valve control arrangement 30L. Both left and right hearing aids 10L, 10R may comprise a valve control arrangement 30L, 30R or a single valve control arrangement, e.g. in the left hearing aid 10L, may control the state of both valves via the wireless communication units 14L, 14R. The valve control arrangement is configured to have an asymmetric state, whereby it sets the position of the two valves 28L, 28R, i.e. the valve 28L in the left hearing aid 10L and the valve 28R in the right hearing aid 10R, in an asymmetric configuration such that one valve is opened more than the other valve as illustrated in FIG. 1, where one valve 28L is fully closed, while the other valve 28R is partially open. The asymmetric state may be configured such that one valve 28L, 28R is fully closed, when the other valve 28L, 28R is open, i.e. such that only one of the valves 28L, 28R in the left and right hearing aids 10L, 10R is partially or fully open, while the other is fully closed.

(14) The left hearing aid 10L additionally comprises a signal processing unit 22L that may comprise a hearing loss processor. The signal processing unit 22L is also configured to create monaural and/or bilateral beamformed signal based on microphone signals from the left hearing aid 10L and/or on a contralateral microphone signal, i.e. a microphone signal from the other, here right, hearing aid. The hearing loss processor is configured to compensate for a hearing loss of a user of the left hearing aid 10L. Preferably, the hearing loss processor comprises a well-known dynamic range compressor circuit or algorithm for compensation of frequency dependent loss of dynamic range of the user often termed recruitment in the art. Accordingly, the signal processing unit 22L can generate and output a beamformed audio signal with additional hearing loss compensation to a loudspeaker or receiver 24L. The loudspeaker or receiver 24L converts the electrical audio signal into a corresponding acoustic signal for transmission into the left ear canal of the user.

(15) The opposite ear hearing aid, in this example the right hearing aid, may generate a monaural or bilateral omnidirectional signal at the opposite ear of the user, where a bilateral omnidirectional signal is based on microphone signals supplied by both the left hearing aid 10L and the right hearing aid 10R. An omnidirectional signal may be generated by mixing a pair of the monaural signals. A bilateral omnidirectional signal exhibits an omnidirectional response or polar pattern with a low directivity index and therefore substantially equal sensitivity for all sound incidence directions or azimuth angles around the user's head, i.e. the shadow effect of the user's head is reduced.

(16) The binaural hearing aid system 1 may additionally comprise an omnidirectional processing arrangement, not shown, which comprises a first omnidirectional signal processor and a second omnidirectional signal processor. The omnidirectional processing arrangement and the signal processing arrangement may be comprised within the same processing unit. The first omnidirectional signal processor is arranged in a housing of the hearing aid comprising the receiver to which a beamformed signal is applied and is configured to generate a first monaural directional signal, transmit the first monaural directional signal to the hearing aid comprising the receiver to which the omnidirectional signal is applied through a wired or wireless communication link 12. Likewise, the second omnidirectional signal processor is arranged in a housing of the hearing aid comprising the receiver to which the omnidirectional signal is applied and is configured to receive the first monaural directional signal, transmitted by the other hearing aid, through the wired or wireless communication link 12. The second omnidirectional signal processor then generates a second monaural directional signal and mixes the first and second monaural directional signals in a fixed or adjustable ratio to generate a bilateral omnidirectional signal.

(17) Advantageously, the valve control arrangement 30L, 30R can be further configured to open the valve 28L, 28R, which is comprised in the hearing aid 10L, 10R having the receiver to which the omnidirectional signal is applied, more than the valve in the hearing aid having the receiver to which the beamformed signal is applied. By doing so a good low frequency gain in provided and ambient noise travelling to the ear is reduced, which increases the effectiveness of the beamforming and noise reduction and therefore increases speech intelligibility.

(18) The skilled person will understand that each of the signal processing units 22L, 22R may comprise a digital processor e.g. a software programmable microprocessor such as a Digital Signal Processor (DSP). Together, the signal processing units 22L, 22R form the signal processing arrangement 22 of the hearing aid system 1. It is preferred that the signal processing arrangement 22 is provided by signal processing units 22L, 22R in each of the hearing aids 10.

(19) However, alternatively, the signal processing arrangement 22 may be located in a single one of the left or right (first or second) hearing aids 10. In such embodiments, the hearing aid where the processing arrangement 22 is located will leverage the communication connection 12 to transmit processed signals, control signals, etc. from to the other hearing aid, and receive microphone signals from the other hearing aid.

(20) The operation of each of the left and right ear hearing aids 10L, 10R may be controlled by a suitable operating system executed on the software programmable microprocessor. The operating system may be configured to manage hearing aid hardware and software resources, e.g. including computation of the bilateral beamforming signal, computation of the monaural beamforming signals, computation of the hearing loss compensation and possibly other processors and associated signal processing algorithms, the wireless data communication unit 14L, certain memory resources etc. The operating system may schedule tasks for efficient use of the hearing aid resources and may further include accounting software for cost allocation, including power consumption, processor time, memory locations, wireless transmissions, and other resources. The operating system may control the operation of the wireless bidirectional data communication unit 14L such that a first monaural beamforming signal is transmitted to the right ear hearing aid 10R and a second monaural beamforming signal is received from the right ear hearing aid through the wireless bidirectional data communication unit 14L and communication connection 12. The right ear hearing aid 10R may have the same hardware components and software components that function in a corresponding manner.

(21) FIG. 2 is a schematic block diagram of an embodiment of a left ear hearing aid 10L for placement at, or in, a user's left ear, of the binaural hearing aid system 1. The illustrated components of the left ear hearing aid 10L may be arranged inside one or several hearing aid housing portion(s) such as BTE, RIE, ITE, ITC, CIC, RIC etc. type of hearing aid housings. The hearing aid 10L comprises a microphone arrangement 20L, which preferably comprises at least the above-mentioned first, and possibly second, omnidirectional microphones 100a, 100b that generate first and second microphone signals, respectively, in response to incoming or impinging sound. Respective sound inlets or ports (not shown) of the first and second omnidirectional microphones 100a, 100b are preferably arranged with a certain spacing in one of the housing portions the hearing aid 10L. The spacing between the sound inlets or ports depends on the dimensions and type of the housing portion, but may lie between 5 and 30 mm. This port spacing range enables the formation of the first monaural beamforming signal by applying sum and delay function or algorithm to the first and second microphone signals. The hearing aid 10L preferably comprises one or more analogue-to-digital converters (not shown), which convert the analogue microphone signals into corresponding digital microphone signals with a certain resolution and sampling frequency before application to a first monaural beamformer 102 and, possibly, a second monaural beamformer 104.

(22) The first monaural beamformer 102 is configured to generate a monaural directional signal 106, e.g. a third monaural directional signal, for example by using a sum-and-delay type of beamforming algorithm. The first monaural beamformer 102 is configured to generate the third monaural directional or beamforming signal 106 based on the digitized first and second microphone signals which beamforming signal 106 preferably has a third polar pattern with maximum response or sensitivity in the target direction, i.e. zero degree direction or look direction of the user. The maximum sensitivity at the target direction, or at least very close thereto, for example within an angular range from 350 degrees-10 degrees, makes the third monaural beamforming signal 106 well-suited as input signal to a bilateral beamformer 108, because the third polar pattern exhibits a reduced sensitivity relative to the maximum sensitivity to incoming sound signals arriving from the ipsilateral side of the user's left ear and from the rear hemisphere of the user's head, i.e. at sound incidence directions or angles of about 180 degrees. The relative attenuation or suppression of the sound arriving from the side and rear directions compared to the target direction may be larger than 6 dB, or larger than 10 dB, such as more than 12 dB or 15 dB, determined at 2 kHz using a narrowband test signal such as a sine wave. The response or sensitivity of the third polar pattern may exhibit the same relative attenuation of these off-axis sound signals within a broader frequency range for example as determined by a 1.5 kHz-5 kHz bandlimited white noise signal.

(23) The second monaural beamformer 104 is configured to generate a first monaural directional signal 110 for example using a sum-and-delay type of beamforming algorithm based on the digitized first and second microphone signals supplied by the microphone arrangement 20L. The first monaural directional signal 110 has a first polar pattern with good sensitivity in the target direction and a maximum sensitivity at, or close to, the ipsilateral side of the user's left ear, determined at 2 kHz, using the azimuthal angular convention indicated on FIG. 7. This substantially equal sensitivity in the target direction and at the ipsilateral side of the user's left ear preferably means that the sensitivity of the first polar pattern varies with less than 6 dB, more preferably less than 4 dB such as less than 2 dB, for sound incidence directions or angular range between 180 degrees and 330 degrees determined at 2 kHz using a narrowband test signal such as a sine wave. The response or sensitivity of the first polar pattern may exhibit the same uniformity for the sound incidence directions between 180 degrees and 330 within a broader frequency range for example as determined by a 1.5 kHz-5 kHz bandlimited white noise signal. The first polar pattern may for example be substantially equal to the open ear directional response of KEMAR's left ear.

(24) The signal processing arrangement 22L is configured to transmit the first monaural directional signal 110 to the right ear or side, i.e. contralateral, hearing aid 10R through RF or NFMI antenna 16L and bidirectional data communication unit 14L using a suitable proprietary communication protocol or standardized communication protocol supporting real-time audio. The skilled person will understand that the first monaural directional signal 110 preferably is encoded in a digital format before wireless transmission—for example a standardized digital audio format. The signal processing arrangement 22L is also configured to receive a fourth monaural directional signal 112 from the right ear hearing aid 10R through the bidirectional data communication unit 14L and wireless communication link 12.

(25) The skilled person will understand that the first monaural beamformer 102 may be implemented as dedicated computational hardware integrated on the signal processing arrangement 22L or implemented by a first set of suitable executable program instructions executed on the signal processing arrangement 22L such as the previously discussed programmable microprocessor or DSP or any combination of dedicated computational hardware and executable program instructions. Likewise, the second monaural beamformer 104 may be implemented as dedicated computational hardware of the signal processing arrangement 22L or implemented by a second set of suitable executable program instructions executed on the signal processing arrangement 22L such as the previously discussed programmable microprocessor or DSP or any combination of dedicated computational hardware and executable program instructions.

(26) The third monaural directional signal 106 and the fourth monaural directional signal 112, where the latter is received from the right ear hearing aid 10R, are applied to inputs of a bilateral beamformer 108, which is configured to generate a bilateral beamforming signal 114 in response based on the third and fourth monaural directional signals 106, 112. The bilateral beamforming signal having a polar pattern with maximum sensitivity in the target direction and relatively reduced sensitivity for all other sound incidence angles including at the ipsilateral side of the left ear hearing aid and at the ipsilateral side of the right ear hearing aid and at the back hemisphere of the user's head, e.g. sound incidence angles about 160-200 degrees, determined at 2 kHz using a narrowband test signal such as a sine wave. The response or sensitivity of the bilateral beamforming signal 114 may exhibit the same relative attenuation of these off-axis sound signals within a broader frequency range for example as determined by a 1.5 kHz-5 kHz bandlimited white noise signal. The sensitivity or response of the bilateral beamforming signal 114 for sound incidence at the ipsilateral side of the left ear hearing aid and at the ipsilateral side of the right ear hearing aid may be at least 10 dB such as more than 12 dB or 15 dB smaller than the sensitivity in the target direction determined at 2 kHz using the narrowband test signal.

(27) The skilled person will understand that the bilateral beamformer 108 may be configured to generate the bilateral beamforming signal 114 by applying various types of fixed or adaptive beamforming algorithms known in the art such as a delay and sum beamforming algorithm or a filter and sum beamforming algorithm.

(28) The signal processing arrangement 22L may be configured to apply the bilateral beamforming signal 114 to a conventional hearing loss processor 116 of the left side hearing aid 10L. The conventional hearing loss processor 116 is configured to compensate a hearing loss of the user of the left hearing aid 10L and provides a hearing loss compensated output signal to the miniature loudspeaker or receiver 24L. The conventional hearing loss processor 116 may comprise an output or power amplifier (not shown) such as a class D amplifier, e.g. digitally modulated Pulse Width Modulator (PWM) or Pulse Density Modulator (PDM) etc., to drive a miniature loudspeaker or receiver 24L. The miniature loudspeaker or receiver 24L converts the electrical hearing loss compensated output signal into a corresponding audible signal, e.g. electrical or acoustic output signal, that can be conveyed to the user's ear drum for example via a suitably shaped and dimensioned ear plug of the left hearing aid 10L.

(29) A sound channel connecting the outside of the left hearing aid 10L to the left ear canal of the user allows a left-ear ambient audio signal 120L to travel towards the ear drum of the user. Within the sound channel a valve 28L regulates how much of the ambient audio signal 120L can pass it by being either fully open, partially open or fully closed. In the embodiment of the left hearing aid shown in FIG. 2, the valve 28L in the left hearing aid 10L is fully closed to reduce the amount of ambient sound travelling to the left ear drum of the user and to provide a good low frequency gain, which increases the effectiveness of the beamforming and noise reduction and therefore increases speech intelligibility. In other instances, the valve 28L may be partially or fully open.

(30) The open or closed state of the valve 28L is controlled by a valve control arrangement 30 via a valve control signal 122 from the valve control arrangement 30L to the valve 28L. The valve control arrangement 30L may be configured to respond to a beamformed signal 114 being applied to the receiver 24L of the hearing aid 10L by closing the valve 28L. This may be done e.g. by a signal 124 from the bilateral beamformer 108 to the valve control arrangement 30.

(31) FIG. 3 is a schematic block diagram of an embodiment of a right ear hearing aid or instrument 10R, for placement at, or in, a user's right ear, of the binaural or bilateral hearing aid system 1. The illustrated components of the right ear hearing aid 10R may be arranged inside one or several hearing aid housing portion(s) such as BTE, RIE, ITE, ITC, CIC, RIC etc. type of hearing aid housings, preferably the same type of housing as the previously discussed left ear hearing aid. The hearing aid 10R comprises a second microphone arrangement 20R which may be identical to the above-mentioned first microphone arrangement 20L and therefore comprise first and second omnidirectional microphones 101a, 101b as illustrated. The hearing aid 10R preferably comprises one or more analogue-to-digital converters (not shown), which convert the analogue microphone signals into corresponding digital microphone signals with a certain resolution and sampling frequency before the corresponding digitized microphone signals are applied to respective inputs of a third monaural beamformer 202 and to respective inputs of a fourth monaural beamformer 204.

(32) The third monaural beamformer 202 is configured to generate the above-discussed fourth monaural directional signal 112. The third monaural beamformer 202 is configured to generate the fourth monaural directional signal 112 for example by using a sum-and-delay type of beamforming algorithm applied to the digitized first and second microphone signals supplied by the second microphone arrangement 20R. The fourth monaural directional signal 112 preferably has a fourth polar pattern with maximum sensitivity in the target direction, i.e. zero degree direction or look direction of the user, i.e. the heading as illustrated on FIG. 7. The maximum sensitivity in the target direction, or at least very close thereto, for example within an angular space from 350 degrees-10 degrees similar to the polar pattern of the third monaural directional signal 106. The fourth polar pattern exhibits a reduced sensitivity relative to the maximum sensitivity to incoming sound arriving from the ipsilateral side of the user's right ear and from the rear hemisphere of the user's head, i.e. at directions of about 180 degrees. The response or sensitivity of the fourth polar pattern may show a relative attenuation or suppression of incoming sound arriving from the ipsilateral side and rear of the user's right ear larger than 6 dB or 10 dB such as larger than 12 dB or even larger than 15 dB determined at 2 kHz using a narrowband test signal such as a sine wave. The response or sensitivity of the fourth polar pattern may exhibit the same relative attenuation of these off-axis sound signals within a broader frequency range for example as determined by a 1.5 kHz-5 kHz bandlimited white noise signal. The fourth monaural directional signal 112 is transmitted to the left ear hearing aid 10L over the wireless communication unit 14R and magnetic coil antenna 16R.

(33) The signal processing arrangement 22 is also configured to implement the functionality of the third monaural beamformer 202, which is configured to generate the second directional microphone signal 206. The second monaural directional signal 206 exhibits a second polar pattern with good sensitivity in the target direction and at the ipsilateral side of the user's right ear, determined at 2 kHz, using the angular convention for sound incidence indicated on FIG. 7. This substantially equal sensitivity in the target direction and at the ipsilateral side of the user's left ear preferably means that the response or sensitivity of the second polar pattern varies with less than 6 dB, more preferably less than 4 dB such as less than 3 dB, in the angular range between 180 degrees and 30 degrees determined at 2 kHz. This substantially equal sensitivity in the target direction and at the ipsilateral side of the user's right ear preferably means that the sensitivity of the second polar pattern varies with less than 6 dB, more preferably less than 4 dB such as less than 2 dB, for sound incidence directions or angular range between 180 degrees and 30 degrees determined at 2 kHz using a narrowband test signal such as a sine wave. The response or sensitivity of the second polar pattern may exhibit the same uniformity for the sound incidence between 180 and 30 degrees within a broader frequency range for example as determined by a 1.5 kHz-5 kHz bandlimited white noise signal. The first polar pattern may for example be substantially equal to the open ear directional response of KEMAR's right ear.

(34) The sensitivity of the second monaural directional signal 206 as reflected in the second polar pattern in the target direction, 360 or 0 degrees, may be about 4-10 dB lower than the sensitivity in the 90 degrees angle for the earlier discussed reasons. The sensitivity of the second monaural directional signal 206 in the target direction, 360 or 0 degrees, may be about 4-10 dB lower than the sensitivity in the 90 degrees direction to allow an appropriate sensitivity of the bilateral omnidirectional signal, aka true-omnidirectional signal, in the target direction after mixing of the second monaural directional signal 206 and a first monaural directional signal 110. The skilled person will appreciate that the polar patterns of the first and second monaural directional signals 110, 206 may be substantially mirror-symmetric about the front-back axis or direction, i.e. from 0 to 180 degrees. The second monaural directional signal 206 possesses a good sensitivity for incoming sound not just from the target direction, but also from a broad angular range about the ipsilateral side of the user's right ear. The skilled person will understand that the second polar pattern preferably is designed such that the sensitivity to sounds arriving at the user's contralateral ear, left ear in the illustrated embodiment, may be significantly smaller than the sensitivity to sounds arriving from the ipsilateral side of the user's left ear, determined at 2 kHz using a narrow-band test signal.

(35) The skilled person will understand that the fourth monaural beamformer 204 may be implemented as dedicated computational hardware integrated on the signal processing arrangement 22 or implemented by a first set of suitable executable program instructions executed on the signal processing arrangement 22 such as the previously discussed programmable microprocessor or DSP or any combination of dedicated computational hardware and executable program instructions. Likewise, the third monaural beamformer 202 may be implemented as dedicated computational hardware of the signal processing arrangement 22 or implemented by a second set of suitable executable program instructions executed on the signal processing arrangement 22 such as the previously discussed programmable microprocessor or DSP or any combination of dedicated computational hardware and executable program instructions.

(36) The skilled person will understand that there exist numerous implementations of the second monaural beamformer 104, which create the first polar pattern of the first monaural directional signal 110 and likewise for the third monaural beamformer 202, which creates the second polar pattern of the second monaural directional signal 206. In certain embodiments of the binaural hearing aid system 1, the second monaural beamformer 104 and the fourth monaural beamformer 204 are entirely omitted which saves computational resources and power consumption of the signal processing arrangement 22. The functionality of the second monaural beamformer 104 and the fourth monaural beamformer 204 are replaced by exploiting natural directional properties of the user's outer ears, e.g. pinnaes and ear canals, for the formation of the first monaural directional signal and the formation of the second monaural directional signal.

(37) The left hearing aid comprises at least one housing portion shaped and sized for placement inside the user's left ear canal. The least one housing portion comprises at least one omnidirectional microphone of the first microphone arrangement 20L with a sound inlet at an outwardly oriented surface of the least one housing portion. Similarly, the right hearing aid comprises least one housing portion shaped and sized for placement inside the user's right ear canal. The at least one housing portion comprises at least one omnidirectional microphone of the right microphone arrangement 20R with a sound inlet at an outwardly oriented surface of the least one housing portion of the right hearing aid. The at least one housing portion of the left hearing aid may be an individually shaped housing of an ITE, CIC or ITC hearing aid or and ear canal plug of an RIC type of hearing aid and the same for the least one housing portion of the right hearing aid.

(38) The signal processing arrangement 22 receives the first monaural directional signal 110 from the left ear hearing aid 10L over the wireless communication unit 14R and magnetic coil antenna 16R. The first monaural directional signal 110 is preferably time delayed relative to the second monaural directional signal 206 before or in connection with being processed by a scaling function 208 and applied to a signal mixer or combiner 210. The relative time delay of the first monaural directional signal 110 is schematically indicated by delay element t1 and includes an inherent transmission time delay of the first monaural directional signal 110 through the wireless communication link 12 and a time delay introduced by the signal processing arrangement 22 to reach a target or desired time delay.

(39) The relatively time-delayed first monaural directional signal 110 is applied to an input of a first scaling function 208, which applies a scaling factor β between 0 and 1 to the first monaural directional signal 110 before a scaled version of the latter is inputted to a signal mixer or combiner 210. The second monaural directional signal 206 is transmitted through an optional time delay function, schematically indicated by delay element t2, before being applied to an input of a second scaling function 212, which applies a scalar scaling factor (1-β) to the second monaural directional signal 206 before the scaled version of the latter signal is applied to a second input of the signal mixer or combiner 210.

(40) The signal mixer or combiner 210 accordingly mixes the first monaural directional signal 110 and the second monaural directional signal 206 in a mixing ratio set by the value of the scalar scaling factor β to generate the bilateral omnidirectional signal 214. The signal processing arrangement 22 may be configured to apply the bilateral omnidirectional signal 214 to the previously discussed conventional hearing loss processor 216 of the right side hearing aid 10R. The conventional hearing loss processor 216 is configured to compensate a hearing loss of the user's right ear and provides a hearing loss compensated output signal to the miniature loudspeaker or receiver 24R. The conventional hearing loss processor 216 and miniature loudspeaker or receiver 24R etc. may be identical to the corresponding components of the above-discussed left ear aid. The target or desired value of the time delay, t1, may be set to a value between 3 ms and 50 ms such as between 5 ms and 20 ms, wherein said time delay is determined at 2 kHz if the time delay varies across the audio frequency range from 100 Hz to 10 kHz.

(41) The introduction of a relative time delay t1 between the first monaural directional signal 110 and the second monaural directional signal 206 leads to several important advantages of the bilateral omnidirectional signal 214 such as providing good perceptual or auditory fusion between the first and second monaural directional signals 110, 206 due to the well-known Haas effect, which is particularly pronounced for relative time delay t1 between 5 and 20 ms. Another advantage of the relative time delay t1 is its decorrelation of the first and second monaural directional signals 110, 206 thereby minimizing signal cancellation effects, when the first and second monaural directional signals 110, 206 are summed or added by the signal mixer or combiner 210.

(42) A sound channel connecting the outside of the right hearing aid 10R to the right ear canal of the user allows a right-ear ambient audio signal 120R to travel towards the ear drum of the user. Within the sound channel a valve 28R regulates how much of the ambient audio signal 120R can pass it by being either fully open, partially open or fully closed. In the embodiment of the right hearing aid shown in FIG. 3, the valve 28R in the right hearing aid 10R is partially or fully open to reduce occlusion and the discomfort associated with it.

(43) The open or closed state of the valve 28R is controlled by a valve control arrangement 30R via a valve control signal 122 from the valve control arrangement 30R to the valve 28R. The valve control arrangement 30R may be configured to respond to an omnidirectional signal 214 being applied to the receiver 24R of the hearing aid 10R by closing the valve 28R. This may be done e.g. by a signal 124 from the signal mixer 210 to the valve control arrangement 30R.

(44) In the embodiments shown in FIGS. 2 and 3, each hearing aid 10R, 10L comprises a valve control arrangement 30R, 30L, however, it may also be that only one of the hearing aids 10R, 10L comprises a valve control arrangement 30 as described above for FIG. 1.

(45) FIG. 4 is a schematic illustration of a hearing impaired individual 401 fitted with a binaural hearing aid system comprising first and second hearing aids 10L, 10R mounted at the user's left and right ears. The illustrative sound source arrangement or setup comprises a target sound source 402, e.g. a desired speaker, placed in a target direction at 0 degrees azimuth. The sound source arrangement may include one or more interfering sound sources 404, 406 arranged around the user's head at various off-axis directions, i.e. outside the target direction.

(46) FIG. 5 is a schematic illustration of the high directivity index of the bilateral beamforming signal 502 applied to the user's left ear and the relatively much lower directivity index of the bilateral omnidirectional signal 504 applied to the user's right ear by exemplary embodiments of the bilateral hearing aid system.

(47) FIG. 6 shows a set of measured polar patterns of the bilateral omnidirectional signal 214 based on a mixing of the first and second monaural directional signals 110, 206 at test frequencies 1, 2 and 4 kHz with the binaural hearing aid system fitted on KEMAR's left and right ears. The bilateral omnidirectional signal 214 is generated using a fixed scalar scaling factor β of 0.5.

(48) FIG. 7 shows respective polar patterns of the bilateral beamforming signal 114 determined at 1 kHz, 2 kHz and 4 kHz for the above-disclosed embodiment of the bilateral beamformer 108. The polar patterns of the bilateral beamforming signal 114 are obtained by measuring its sensitivity as a function of the azimuthal angles 0-360 degrees of the test sound source. The left side and right side hearing aids are appropriately placed on KEMAR or a similar acoustic manikin which simulates average acoustic properties of the human head and torso. The test sound source may generate a broad-band test signal such as a Maximum-Length Sequence (MLS) sound signal which is reproduced at each azimuthal angle from 0 to 360 degree in steps of a predetermined size, e.g. 5 or 10 degrees. The acoustic transfer function is derived from the bilateral beamformed signal 114 and the test signal. The power spectrum of the acoustic transfer function represents a magnitude response of the bilateral beamforming signal 114 at each azimuthal angle. For adaptive beamformers and beamforming algorithms, in order to avoid over-estimating sensitivity of the beamforming signal 114, it may be advantageous to apply a Schroeder phase complex harmonic as the acoustic test sound signal in a diffuse sound field to simulate a realistic acoustic environment of the user. The magnitude spectral response may for example be estimated based on harmonics amplitude between the test sound signal playback and the bilateral beamforming signal 114 obtained in response.

(49) Items

(50) 1. A binaural hearing aid system comprising:

(51) a first hearing aid for placement at, or in, a user's left or right ear, said first hearing aid comprising a first microphone arrangement, a first wireless communications unit, a first receiver, and a first sound channel comprising a first valve which is movable from an open state to a closed state and from a closed state to an open state;

(52) a second hearing aid for placement at, or in, the user's opposite ear, said second hearing aid comprising a second microphone arrangement, a second wireless communications unit, and a second sound channel comprising a second valve which is movable from an open state to a closed state and from a closed state to an open state;

(53) a signal processing arrangement adapted for generating a beamformed signal based on microphone signals supplied by the first and/or second microphone arrangement(s) and for applying the beamformed signal to the first and/or second receiver(s); and

(54) a valve control arrangement which has an asymmetric mode, in which asymmetric mode the valve control arrangement is configured to asymmetrically control the first and second valves by moving the first and second valves into positions wherein one of the first or second valves is opened more than the other of the first or second valves.

(55) 2. The binaural hearing aid system according to item 1, wherein the signal processing arrangement is adapted for generating an omnidirectional signal based on microphone signals supplied by the first and/or second microphone arrangement(s), and wherein the signal processing arrangement is adapted for applying the beamformed signal to one of the first or the second receiver and applying the omnidirectional signal to the other one of the first or the second receiver.

(56) 3. The binaural hearing aid system according to item 2, wherein the valve control arrangement is further configured to open the valve, which is comprised in the hearing aid comprising the receiver to which the omnidirectional signal is applied, more than the valve, which is comprised in the hearing aid comprising the receiver to which the beamformed signal is applied, when in the asymmetric mode.

(57) 4. The binaural hearing aid system according to any of items 2 or 3, wherein the omnidirectional signal is a bilateral omnidirectional signal based on microphone signals supplied by the first and second microphone arrangements.

(58) 5. The binaural hearing aid system according to item 4, wherein the microphone signal supplied by the hearing aid comprising the receiver to which the beamformed signal is applied is time delayed relative to the microphone signal supplied by the hearing aid comprising the receiver to which the omnidirectional signal is applied before the two microphone signals are mixed to generate the bilateral omnidirectional signal.

(59) 6. The binaural hearing aid system according to any of the previous items, wherein the beamformed signal is based at least on two or more microphone signals supplied in response to incoming sound by the microphone arrangement comprised in the hearing aid comprising the receiver to which the beamformed signal is applied.

(60) 7. The binaural hearing aid system according to any of items 2-6, wherein the hearing aid system further comprises an omnidirectional processing arrangement, which comprises a first omnidirectional signal processor and a second omnidirectional signal processor;

(61) the first omnidirectional signal processor being arranged in a housing of the hearing aid comprising the receiver to which the beamformed signal is applied and being configured to: generating a first monaural directional signal, transmitting, through a wired or wireless communication link, the first monaural directional signal to the hearing aid comprising the receiver to which the omnidirectional signal is applied; and

(62) the second omnidirectional signal processor being arranged in a housing of the hearing aid comprising the receiver to which the omnidirectional signal is applied and being configured to: receiving the first monaural directional signal, transmitted by the other hearing aid, through the wired or wireless communication link, generating a second monaural directional signal and mixing the first and second monaural directional signals in a fixed or adjustable ratio to generate a bilateral omnidirectional signal.

(63) 8. The binaural hearing aid system according to item 7, wherein the signal processing arrangement and the omnidirectional processing arrangement are comprised in the same processing unit.

(64) 9. The binaural hearing aid system according to any of items 1-8, wherein the signal processing arrangement comprises a first signal processing unit housed in the first hearing aid and a second signal processing unit housed in the second hearing aid.

(65) 10. The binaural hearing aid system according to any of the preceding items, wherein the valve control arrangement is additionally configured to fully close the first valve, when the second valve is opened and to fully close the second valve, when the first valve is opened.

(66) 11. The binaural hearing aid system according to any of the preceding items, wherein the valve of the first or the second hearing aid is opened by the valve control arrangement in response to an omnidirectional signal being applied to the receiver of the first or second hearing aid, respectively; and/or

(67) wherein the valve of the first or second hearing aid is closed by the valve control arrangement in response to a beamformed signal being applied to the receiver of the first or second hearing aid, respectively.

(68) 12. The binaural hearing aid system according to any of the preceding items, wherein the first valve is further configured to open at least partially or close at least partially in response to a first valve control signal and the second valve is further configured to open at least partially or close at least partially in response to a second valve control signal.

(69) 13. The binaural hearing aid system according to any of the preceding items, wherein the first sound channel is located in a part of the first hearing aid which resides in an ear canal of the user during use and the second sound channel is located in a part of the second hearing aid which resides in the opposite ear canal of the user during use.

(70) 14. The binaural hearing aid system according to any of the preceding items, wherein the valve control arrangement is adapted to engage the asymmetric mode in response to the hearing aid system entering a conversation mode, the conversation mode being entered upon request by the user or in response to a signal strength of microphone signal from the first and or second microphone arrangements crossing a noise threshold.

(71) 15. A method of providing a beamformed signal at a left or right ear of a hearing aid user and a bilateral omnidirectional signal at the opposite ear of the hearing aid user; the method comprising: by a beamforming arrangement generating a bilaterally or monaurally beamformed signal based at least on two or more microphone signals supplied by a microphone arrangement of a hearing aid in the user's left or right ear; converting the bilaterally or monaurally beamformed signal into a corresponding audible beamformed signal for the user's corresponding left or right ear; by an omnidirectional processing arrangement generating a first monaural directional signal based on one or more microphone signals supplied by the microphone arrangement of a hearing aid in the user's left or right ear; by an omnidirectional processing arrangement generating a second monaural directional signal based on one or more microphone signals supplied by the microphone arrangement of the opposite hearing aid; mixing the first and second monaural directional signals in a fixed or adjustable ratio to generate the bilateral omnidirectional signal; converting the bilateral omnidirectional signal into a corresponding audible omnidirectional signal for the user's opposite ear, and by a valve control arrangement carrying out steps of closing a valve in the hearing aid in the user's left or right ear; and opening a valve in the hearing aid in the user's opposite ear.

LIST OF REFERENCES

(72) 1 Binaural hearing aid system 10 Left/Right hearing aid 12 Data communication connection or link 14 Wireless communication unit 16 Antennas 18 Hearing aid circuit 20 Microphone arrangement 22 Signal processing arrangement 22L Signal processing unit 22R Signal processing unit 24 Receiver 26 Sound channel 28 Valve 30 Valve control arrangement 100 Omnidirectional microphones 102 First monaural beamformer 104 Second monaural beamformer 106 Third monaural directional signal 108 Bilateral beamformer 110 First monaural directional signal 112 Fourth monaural directional signal 114 Bilateral beamforming signal 116 Conventional hearing loss processor 120 Ambient audio signal 122 Valve control signal 124 Signal from bilateral beamformer to valve control arrangement 202 Third monaural beamformer 204 Fourth monaural beamformer 206 Second monaural directional signal 208 First scaling function 210 Signal mixer or combiner 212 Second scaling function 214 Bilateral omnidirectional signal 216 Conventional hearing loss processor 401 Hearing-impaired individual 402 Target sound source 404 Interfering sound source 406 Interfering sound source 502 Directivity of bilateral beamforming signal 504 Directivity of bilateral omnidirectional signal t1,t2 delay element