Hearing device comprising an input transducer in the ear
A hearing aid configured to be worn at, and/or in, an ear of a user, comprises a forward path for processing sound from the environment of the user. The forward path comprises a) at least one first microphone providing at least one first electric input signal representing said sound as received at the respective at least one first microphones, said at least one first microphone being located away from a first ear canal of the user, b) an audio signal processor for processing said at least one first electric input signal, or a signal or signals originating therefrom, and for providing a processed signal, c) an output transducer for providing stimuli perceivable as sound to the user in dependence of said processed signal, and d) at least one second microphone connected to said audio signal processor, the at least one second microphone being configured to provide at least one second electric input signal representing said sound as received at the at least one second microphone, the at least one second microphone being located at or in said first ear canal of the user, and e) a feature extractor for extracting acoustic characteristics of said ear of the user from said at least one second electric input signal, or a signal originating therefrom. The hearing aid is configured to include said acoustic characteristics in the processed signal. The invention may e.g. provide improved sound localization in hearing aids.
1. A hearing aid configured to be worn at, and/or in, an ear of a user, the hearing aid comprising
a forward path for processing sound from the environment of the user, the forward path comprising
at least one first microphone providing at least one first electric input signal representing said sound as received at the respective at least one first microphones, said at least one first microphone being located away from a first ear canal of the user, wherein the at least one first microphone comprises at least two first microphones providing respective at least two first electric input signals,
an audio signal processor for processing said at least one first electric input signal, or a signal or signals originating therefrom, and for providing a processed signal, wherein the audio signal processor comprises a directional system for providing at least one beamformer comprising predefined and/or adaptively updated beamformer weights, and for providing at least one beamformed signal in dependence of said at least two first electric input signals and said at least one beamformer, and a postfilter for filtering said beamformed signal, or a signal originating therefrom, based on adaptively updated postfilter gains and configured to provide a filtered signal,
an output transducer for providing stimuli perceivable as sound to the user in dependence of said processed signal,
at least one second microphone connected to said audio signal processor, the at least one second microphone being configured to provide at least one second electric input signal representing said sound as received at the at least one second microphone, the at least one second microphone being located at or in said first ear canal of the user,
a feature extractor for extracting acoustic characteristics of said ear of the user from said at least one second electric input signal, or a signal originating therefrom, wherein the feature extractor is configured to extract acoustic characteristics as magnitude and phase properties, wherein the hearing aid is configured to include said acoustic characteristics in the processed signal in that said postfilter is configured to determine said postfilter gains in dependence of said extracted acoustic characteristics as complex values including magnitude and phase.
2. A hearing aid according to claim 1 wherein the feature extractor comprises an envelope extractor for extracting said acoustic characteristics, the envelope extractor being configured to determine an envelope and/or envelope cues of the at least one second electric input signal, or a signal originating therefrom, and to provide an envelope signal representative thereof.
3. A hearing aid according to claim 2 , wherein
the hearing aid comprises a postfilter for filtering said at least one electric input signal or said beamformed signal, or a signal originating therefrom, based on adaptively updated postfilter gains and configured to provide a filtered signal, and
the postfilter is configured to determine said postfilter gains in dependence of said envelope signal.
4. A hearing aid according to claim 2 wherein the postfilter is configured to determine said postfilter gains in dependence of said envelope signal.
5. A hearing aid according to claim 1 wherein the feature extractor for extracting acoustic characteristics of an ear of the user is configured to include magnitude and phase properties of the acoustic characteristics below a LF-HF-threshold frequency (f LF-HF ) and to focus on magnitude properties of the acoustic characteristics above the LF-HF-threshold frequency.
6. A hearing aid according to claim 1 wherein the LF-HF-threshold frequency (f LF-HF ) smaller than or equal to 2.5 kHz.
7. A hearing aid according to claim 1 wherein the feature extractor is configured to determine said acoustic characteristics of said ear of the user in dependence of A) a level difference measure indicative of a level difference between the at least one second electric input signal and the at least one first electric input signal, or envelopes thereof, and B) a phase difference measure relating to a difference in phase between the at least one second electric input signal and the at least one first electric input signal.
8. A hearing aid according to claim 7 wherein said postfilter is configured to determine said postfilter gains in dependence of said difference measure.
9. A hearing aid according to claim 1 , wherein
the feature extractor is configured to determine said acoustic characteristics of said ear of the user in dependence of difference measure indicative of a difference between the at least one second electric input signal and the at least one first electric input signal, or envelopes thereof, and
said postfilter is configured to determine said postfilter gains in dependence of said difference measure.
10. A hearing aid according to claim 1 comprising a BTE-part adapted for being located at or behind an ear (pinna) of the user, and wherein the at least one first microphone is located in said BTE-part.
11. A hearing aid according to claim 1 comprising an ITE-part adapted for being located at or in an ear canal of the user, and wherein the at least one second microphone is located in said ITE-part.
12. A hearing aid according to claim 1 comprising a feedback control system for estimating and/or attenuating feedback from said output transducer to one or more of said at least one first microphones and said at least one second microphone and wherein the feedback control system is configured to provide a reliability estimate of the at least one second electric input signal in dependence of said feedback estimate.
13. A hearing aid according to claim 1 being constituted by or comprising an air-conduction type hearing aid, a bone-conduction type hearing aid, a cochlear implant type hearing aid, or a combination thereof.
14. A hearing aid according to claim 1 wherein a border frequency (f LF-HF ) is defined wherein the acoustic characteristics of said ear are dominated by phase modifications of the acoustic signal impinging on the ear (pinna) at relatively low frequencies below the border frequency (f LF-HF ) and are dominated by amplitude modifications at relatively high frequencies above the border frequency (f LF-HF ).
15. A hearing aid according to claim 14 wherein the border frequency (f LF-HF ) between low and high frequencies is larger than 1 kHz.
16. A hearing aid according to claim 14 wherein the border frequency (f LF-HF ) between low and high frequencies is in the range between 1 kHz and 4 kHz.
17. A hearing aid according to claim 14 wherein the border frequency (f LF-HF ) between low and high frequencies is smaller than or equal to 2.5 kHz.
18. A hearing aid according claim 1 wherein the feature extractor is configured to determine said acoustic characteristics of the ear of the user in dependence of a level difference measure indicative of a difference in level between the at least one second electric input signal and the at least one first electric input signal.
19. A hearing aid according to claim 18 wherein the postfilter is configured to determine said postfilter gains in dependence of the level and/or phase differences.
20. A hearing aid according to claim 19 wherein the postfilter gain increases with increasing level difference and decreases with decreasing level difference.
21. A hearing aid according to claim 1 wherein the feature extractor is configured to determine said acoustic characteristics of the ear of the user in dependence of a phase difference between the at least one second electric input signal and the at least one first electric input signal.
22. A hearing aid according to claim 21 wherein the postfilter gain includes a cap beyond which the gain does not increase, or decrease, further, respectively, for increasing or decreasing level difference.