Hearing aids with adaptive beamformer responsive to off-axis speech

1. A hearing assistance system for receiving and processing sounds with control of directionality of sound reception, comprising:

a processor configured to process the received sounds and including an adaptive directionality controller configured to control a target direction of the sound reception using a beamformer configured to cancel sound signals that are not coming from the target direction, the sound signals including off-axis speech and noise, the adaptive directionality controller configured to:

detect the off-axis speech; and

steer the beamformer to reduce the cancellation of the off-axis speech without substantially changing the cancellation of the noise in response to a detection of the off-axis speech.

2. The system of claim 1 , wherein the adaptive directionality controller is programmed to detect the off-axis speech using output of forward-looking and rearward-looking cardioids.

3. The system of claim 1 , wherein the adaptive directionality controller is programmed to:

calculate a rearward signal-to-noise ratio (SNR), the rearward SNR being the SNR of a rearward-looking cardioid; and

detect the off-axis speech using the rearward SNR.

4. The system of claim 3 , wherein the adaptive directionality controller is programmed to:

compare the rearward SNR to a specified threshold SNR; and

indicate the detection of the off-axis speech in response to the rearward SNR being larger than the specified threshold SNR.

5. The system of claim 3 , wherein the adaptive directionality controller is programmed to:

calculate a forward SNR, the forward SNR being the SNR of a forward-looking cardioid;

compare the rearward SNR to the forward SNR; and

indicate a rear source of the off-axis speech in response to the rearward SNR exceeding the forward SNR by a specified margin.

6. The system of claim 1 , wherein the adaptive directionality controller is programmed to:

create an alternative beamformer at an angle away from a current beamformer;

calculate an alternative signal-to-noise ratio (SNR) and a normal SNR, the alternative SNR being the SNR of the alternative beamformer, the normal SNR being the SNR of the current beamformer; and

detect the off-axis speech using the alternative SNR and the normal SNR.

7. The system of claim 6 , wherein the adaptive directionality controller is programmed to:

compare the alternative SNR to a specified threshold SNR;

compare the alternative SNR to the normal SNR in response to the alternative SNR exceeding the specified threshold SNR; and

indicate the detection of the off-axis speech in response to the alternative SNR exceeding the normal SNR by a specified margin.

8. The system of claim 7 , wherein the adaptive directionality controller is programmed to steer the current beamformer towards the alternative beamformer in response to the detection of the off-axis speech being indicated.

9. A hearing assistance system for transmitting sounds into one or more ear canals, comprising:

a plurality of microphones configured to receive sounds;

one or more receivers configured to deliver processed sounds to the one or more ear canals; and

a processor coupled between the plurality of microphones and the one or more receivers, the processor configured to process the received sounds and including an adaptive directionality controller configured to control a target direction, the adaptive directionality controller including:

a beamformer configured to cancel off-axis sounds of the received sounds, the off-axis sounds being sounds that are not from the target direction;

a speech detector configured to detect off-axis speech of the off-axis sounds; and

a steering module configured to steer the beamformer in response to a detection of the off-axis speech to reduce the cancellation of the off-axis speech without changing the cancellation of noise of the off-axis sounds substantially.

10. The system of claim 9 , comprising one or more hearing aids including the plurality of microphones, the one or more receivers, and the processor.

11. The system of claim 10 , comprising a mononaural hearing aid including the plurality of microphones, the one or more receivers, and the processor.

12. The system of claim 10 , comprising a pair of binaural hearing aids each including at least one microphone of the plurality of microphones, at least one receiver of the one or more receivers, and a portion of the processor.

13. The system of claim 10 , wherein the one or more hearing aids are each configured as a behind-the-ear (BTE) hearing aid.

14. The system of claim 10 , wherein the one or more hearing aids are each configured as an in-the-ear (ITE) hearing aid.

15. The system of claim 14 , wherein the one or more hearing aids are each configured as an in-the-canal (ITC) hearing aid.

16. A method for adaptive control of a target direction of sound reception by a hearing assistance system, the method comprising:

using a beamformer to cancel off-axis sound signals that are not from the target direction, the off-axis sound signals including noise;

detecting off-axis speech from the off-axis sound signals; and

steering the beamformer to reduce the cancellation of the off-axis speech by the beamformer without substantially changing the cancellation of the noise by the beamformer in response to a detection of the off-axis speech.

17. The method of claim 16 , wherein detecting the off-axis speech comprises detecting the off-axis speech using output of forward-looking and rearward-looking cardioids.

18. The method of claim 16 , wherein detecting the off-axis speech comprises:

calculating a rearward signal-to-noise ratio (SNR), the rearward SNR being the SNR of a rearward-looking cardioid;

detecting the off-axis speech using the rearward SNR and a specified threshold SNR.

19. The method of claim 18 , wherein detecting the off-axis speech further comprises:

calculating a forward SNR, the forward SNR being the SNR of a forward-looking cardioid;

detecting a rear source of the off-axis speech using the rearward SNR and the forward SNR.

20. The method of claim 16 , wherein detecting the off-axis speech comprises:

creating an alternative beamformer at an angle away from a current beamformer; and

detecting the off-axis speech using the alternative beamformer and the current beamformer.

21. The method of claim 20 , wherein detecting the off-axis speech comprises:

calculating an alternative signal-to-noise ratio (SNR), the alternative SNR being the SNR of the alternative beamformer;

calculating a normal SNR, the normal SNR being the SNR of the current beamformer; and

detecting the off-axis speech using the alternative SNR and the normal SNR.

22. The method of claim 21 , wherein steering the beamformer comprises steering the current beamformer towards the alternative beamformer in response to the off-axis speech being detected.