Hearing aid and feedback canceller
A hearing aid according to an embodiment of the present disclosure includes: a microphone configured to convert sound into an electric signal and output a first signal; a receiver configured to convert the third signal that is generated by performing predetermined hearing aid processing on a second signal, into sound; a first feedback removal unit having an adaptive filter configured to adaptively estimate a first transfer function of a sound feedback path from the receiver to the microphone; and a second feedback removal unit having a fixed filter configured to receive the third signal and use a fixed filter coefficient based on a second transfer function of a vibration feedback path from the receiver to the microphone. The second signal is generated by removing from the first signal, output signals from the adaptive filter and the fixed filter.
1. A hearing aid comprising:
a microphone configured to convert sound into an electric signal and output a first signal;
a hearing aid processing unit configured to perform predetermined hearing aid processing on a second signal generated based on the first signal to generate a third signal;
a receiver configured to convert the third signal into sound;
a first feedback removal unit having an input filter configured to attenuate a predetermined low-frequency band component included in the third signal, and an adaptive filter configured to receive an output signal from the input filter and adaptively estimate a first transfer function of a sound feedback path from the receiver to the microphone; and
a second feedback removal unit having a fixed filter configured to receive the third signal and use a fixed filter coefficient based on a second transfer function of a vibration feedback path from the receiver to the microphone, wherein
the first feedback removal unit and the second feedback removal unit are connected in parallel to each other, and
the second signal is generated by removing from the first signal an output signal from the adaptive filter included in the first feedback removal unit and an output signal from the fixed filter included in the second feedback removal unit.
2. The hearing aid according to claim 1 , wherein
the second feedback removal unit includes a first subtraction unit configured to subtract from the first signal an output signal from the fixed filter and output a fourth signal, and
the first feedback removal unit includes a second subtraction unit configured to subtract from the fourth signal an output signal from the adaptive filter and output the second signal.
3. The hearing aid according to claim 1 , wherein the hearing aid is switchable between a first operation mode in which to operate both of the first and second feedback removal units and a second operation mode in which to operate only the second feedback removal unit.
4. The hearing aid according to claim 2 , wherein the hearing aid is switchable between a first operation mode in which to operate both of the first and second feedback removal units and a second operation mode in which to operate only the second feedback removal unit.
5. A hearing aid comprising:
a microphone configured to convert sound into an electric signal and output a first signal;
a hearing aid processing unit configured to perform predetermined hearing aid processing on a second signal generated based on the first signal to generate a third signal;
a receiver configured to convert the third signal into sound;
a telephone coil configured to convert a magnetic signal into an electric signal and output a fifth signal;
a first feedback removal unit having an input filter configured to attenuate a predetermined low-frequency band component included in the third signal, and an adaptive filter configured to receive an output signal from the input filter and adaptively estimate a first transfer function of a sound feedback path from the receiver to the microphone;
a second feedback removal unit having a fixed filter configured to receive the third signal and use a fixed filter coefficient based on a second transfer function of a vibration feedback path from the receiver to the microphone; and
a third feedback removal unit having a fixed filter configured to receive the third signal and use a fixed filter coefficient based on a third transfer function of a magnetic field feedback path from the receiver to the telephone coil, wherein
the second signal is generated by removing an output signal from the first feedback removal unit, an output signal from the second feedback removal unit, and an output signal from the third feedback removal unit, based on the first signal and the fifth signal.
6. A feedback canceller comprising: a first conversion device configured to convert sound into an electric signal and output a first signal; a signal processing unit configured to perform predetermined hearing aid processing on a second signal generated based on the first signal to generate a third signal; a second conversion device configured to convert the third signal into sound; a first feedback removal unit comprising an input filter configured to attenuate a predetermined low-frequency band component included in the third signal, and an adaptive filter configured to receive an output signal from the input filter and adaptively estimate a first transfer function of a sound feedback path from the second conversion device to the first conversion device; and a second feedback removal unit comprising a fixed filter configured to receive the third signal and use a fixed filter coefficient based on a second transfer function of a vibration feedback path from the second conversion device to the first conversion device, wherein the first feedback removal unit and the second feedback removal unit are connected in parallel to each other, and the second signal is generated by removing from the first signal an output signal from the adaptive filter included in the first feedback removal unit and an output signal from the fixed filter included in the second feedback removal unit.
7. The feedback canceller according to claim 6 , wherein
the second feedback removal unit includes a first subtraction unit configured to subtract from the first signal an output signal from the fixed filter and output a fourth signal, and
the first feedback removal unit includes a second subtraction unit configured to subtract from the fourth signal an output signal from the adaptive filter and output the second signal.