Hearing aid apparatus
View Patent ↗The present application is directed to a hearing aid apparatus for wearing use by a user, including a frontend sound collector configured to collect a frontend signal; a backend sound collector configured to collect a backend signal; and a sound processor configured to process the frontend signal and the backend signal; wherein the sound processor includes a frontend delayer configured to apply a delay coefficient to the frontend signal to produce a delayed frontend signal; a backend delayer configured to apply the delay coefficient to the backend signal to produce a delayed backend signal; and an adaptive filter configured to process the delayed frontend signal and the delayed backend signal to produce an adaptive filter output signal.
1. A hearing aid apparatus for wearing use by a user comprising:
a frontend sound collector configured to collect a frontend signal;
a backend sound collector configured to collect a backend signal; and
a sound processor configured to process the frontend signal and the backend signal; wherein the sound processor comprise:
a frontend delayer configured to apply a frontend delay coefficient to the frontend signal to produce a delayed frontend signal;
a backend delayer configured to apply a backend delay coefficient to the backend signal to produce a delayed backend signal;
a multiplier configured to weight the delayed backend signal by a backend coefficient to produce a weighted backend signal; and
an adaptive filter configured to process the delayed frontend signal and the weighted backend signal to produce an adaptive filter output signal;
wherein the frontend sound collector comprises a left channel frontend collector configured to collect a left channel frontend signal and a right channel frontend collector configured to collect a right channel frontend signal; and
the backend sound collector comprises a left channel backend collector configured to collect a left channel backend signal and a right channel backend collector configured to collect a right channel backend signal;
the frontend delayer comprises a left channel frontend delayer configured to apply a left channel frontend delay coefficient to the left channel frontend signal to produce a delayed left channel frontend signal and a right channel frontend delayer configured to apply a right channel frontend delay coefficient to the right channel frontend signal to produce a delayed right channel frontend signal;
the backend delayer comprises a left channel backend delayer configured to apply a left channel backend delay coefficient to the left channel backend signal to produce a delayed left channel backend signal and a right channel backend delayer configured to apply a right channel backend delay coefficient to the right channel backend signal to produce a delayed right channel backend signal; and
the multiplier comprises a left channel multiplier configured to weight the delayed left channel backend signal by a left channel backend coefficient to produce a weighted left channel backend signal and a right channel multiplier configured to weight the delayed right channel backend signal by a right channel backend coefficient to produce a weighted right channel backend signal.
2. A hearing aid apparatus according to claim 1 , wherein the adaptive filter comprises a left channel adaptive filter configured to process the delayed left channel frontend signal and the weighted left channel backend signal to produce a left channel adaptive filter output signal and a right channel adaptive filter configured to process the delayed right channel frontend signal and the weighted right channel backend signal to produce a right channel adaptive filter output signal.
3. A hearing aid apparatus according to claim 2 , wherein the left channel adaptive filter output signal and the right channel adaptive filter output signal are calculated by following equations:
y L(n) =X L(n) h L(n) ,
where y L(n) is the left channel adaptive filter output signal, and
h L(n+1) =h L(n) −2γ L μ L(n) x L(n+d L ) n L(n+d L ) ;
y R(n) =X R(n) h R(n) ,
where y R(n) is the right channel adaptive filter output signal, and
h R(n+1) =h R(n) −2γ R μ R(n) x R(n+d R ) n R(n+d R ) ; where
n represents a n th time slot, n+1 represents a (n+1) th time slot next to the n th time slot; n is a positive integer;
γ L is the left channel backend coefficient;
γ R is the right channel backend coefficient;
x L(n) is the left channel frontend signal;
x R(n) is the right channel frontend signal;
n L(n) is the left channel backend signal;
n R(n) is the right channel backend signal;
λ BF is a beamforming coefficient;
μ L is a left channel adaptation coefficient;
μ R is a right channel adaptation coefficient;
h L(n) is a left channel adaptive filter;
h R(n) is a right channel adaptive filter;
d L is the left channel frontend delay coefficient and the left channel backend delay coefficient; and
d R is the right channel frontend delay coefficient and the right channel backend delay coefficient.
4. A hearing aid apparatus according to claim 2 , further comprising:
a beamformer configured to beamforming the left channel adaptive filter output signal and the right channel adaptive filter output signal and output a beamformer sound output signal.
5. A hearing aid apparatus according to claim 4 , wherein
the beamformer comprises:
a left channel BF delayer configured to apply a left channel BF delay coefficient to the left channel adaptive filter output signal to produce a delayed left channel BF signal;
a right channel BF delayer configured to apply a right channel BF delay coefficient to the right channel adaptive filter output signal to produce a delayed right channel BF signal;
a left channel BF multiplier configured to weight the delayed left channel BF signal by the beamforming coefficient to produce a weighted left channel BF signal;
a right channel BF multiplier configured to weight the delayed right channel BF signal by the beamforming coefficient to produce a weighted right channel BF signal;
a left channel adder configured to add the delayed left channel BF signal and the weighted right channel BF signal to produce a left channel summed signal;
a right channel adder configured to add the weighted left channel BF signal and the delayed right channel BF signal to produce a right channel summed signal; and
a BF adaptive filter configured to adaptively filter the left channel summed signal and the right channel summed signal to produce the beamformer sound output signal.
6. A hearing aid apparatus according to claim 5 , wherein
the beamformer sound output signal is calculated by following equations:
X BF(n) =y 1(n) h BF(n) ,
where X BF(n) is the beamformer sound output signal, and
h BR(n+1) =h BF(n) −2μ X BF(n) y 2(n) ;
y 1(n) =x L(n+τ 1 ) +λ BF x R(n+τ 2 )
y 2(n) =λ BF x L(n+τ 1 ) +x R(n+τ 2 ) ;
Where
n represents a n th time slot, n+1 represents a (n+1) th time slot next to the n th time slot; n is a positive integer;
μ is an adaptive filter coefficient;
τ 1 is the left channel BF delay coefficient; and
τ 2 is the right channel BF delay coefficient.
7. A hearing aid apparatus according to claim 5 , further comprising:
a left channel adaptive noise canceller (ANC) configured to process the beamformer sound output signal and output a left channel estimated clean sound output signal; and
a right channel ANC configured to process the beamformer sound output signal and output a right channel estimated clean sound output signal.
8. A hearing aid apparatus according to claim 7 , wherein
the left and right ANCs each comprise:
a Time-to-Frequency converter configured to convert the beamformer sound output signal into a frequency-domain signal;
a noise detector configured to detect speech and noise from the frequency-domain signal;
a noise spectrum estimator configured to calculate an estimated noise spectrum from the noise;
a spectrum subtractor configured to calculate an estimated clean sound spectrum from the speech and the estimated noise spectrum;
a Frequency-to-Time converter configured to convert the estimated clean sound spectrum into a time-domain estimated clean sound output.
9. A hearing aid apparatus according to claim 8 , wherein
the left channel estimated clean sound output signal and the right channel estimated clean sound output signal are calculated by following equations:
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where
x L(n) is the left channel frontend signal,
x R(n) is the right channel frontend signal,
X L(w) is a left channel spectrum of x L(n) ,
X R(w) is a right channel spectrum of x R(n) ,
|X L(w) | is a left channel magnitude spectrum,
|X R(w) | is a right channel magnitude spectrum,
∠(X L(w) ) is a left channel phase spectrum,
∠(X R(w) ) is a right channel phase spectrum,
Ñ L(w) is a left channel estimated noise spectrum,
Ñ R(w) is a right channel estimated noise spectrum,
{tilde over (S)} L(w) is a left channel estimated clean sound spectrum,
{tilde over (S)} R(w) is a right channel estimated clean sound spectrum,
{tilde over (S)} L(n) is the left channel estimated clean sound output,
{tilde over (S)} R(n) is the right channel estimated clean sound output,
β L is a left channel noise spectrum coefficient,
β R is a right channel noise spectrum coefficient,
α L is a left channel spectral subtraction coefficient,
α R is a right channel spectral subtraction coefficient.
10. A hearing aid apparatus according to claim 8 , wherein
a Fast Fourier Transform (FFT) is performed in the Time-to-Frequency converter; and
an Inverse Fast Fourier Transform (IFFT) is performed in the Frequency-to-Time converter.
11. A hearing aid apparatus according to claim 3 , wherein
the left channel backend coefficient γ L is equal to 0.05;
the right channel backend coefficient γ R is equal to 0.05; and
the beamforming coefficient λ BF is equal to 0.5.
12. A hearing aid apparatus according to claim 3 , wherein
the left channel backend coefficient γ L is equal to 0.02;
the right channel backend coefficient γ R is equal to 0.02; and
the beamforming coefficient λ BF is equal to 0.7.
13. A hearing aid apparatus according to claim 3 , wherein
the left channel backend coefficient γ L is equal to 0.01;
the right channel backend coefficient γ R is equal to 0.01; and
the beamforming coefficient λ BF is equal to 1.
14. A hearing aid apparatus according to claim 1 , wherein
the sound processor is a Digital Signal Processor (DSP).
15. A hearing aid apparatus according to claim 1 , further comprising:
a Bluetooth module and a Radio module as wireless transceivers which connect the sound processor.
16. A hearing aid frontend according to claim 1 , wherein the sound processor is configured to select sounds of within ±30 degrees of a forward axis of the user.
17. A hearing aid frontend according to claim 1 , wherein a transverse separation distance between the left channel frontend collector and the right channel frontend collector is user adjustable.
18. A hearing aid frontend according to claim 17 , wherein the transverse separation distance is set to be between 15 cm to 18 cm.