Hearing aid noise reduction method, system, and apparatus

1. A hearing aid, comprising:

an input device configured to output a first signal, the first signal comprising a noise signal;

a receiver;

a noise estimator in a signal path between the input device and the receiver, the noise estimator comprising:

a first low-pass filter configured to filter first periodic samples of the first signal, the first periodic samples being approximately periodic with respect to a period of the noise signal, the first low-pass filter further configured to provide a time average of a first sample position of the period of the noise signal; and

a second low-pass filter configured to filter second periodic samples of the first signal, the second periodic samples being approximately periodic with respect to the period of the noise signal, the second periodic samples being phase shifted relative to the first periodic samples, the second low-pass filter further configured to provide a time average of a second sample position of the period of the noise signal.

2. The hearing aid of claim 1 , wherein:

the noise estimator is configured to estimate a waveform of the noise signal.

3. The hearing aid of claim 2 , further comprising:

an arithmetic unit configured to subtract the waveform of the noise signal from the first signal to provide a desired signal.

4. The hearing aid of claim 1 , further comprising a plurality of low-pass filters, wherein:

each filter in the plurality of low-pass filters is configured to filter a corresponding stream of periodic samples from a plurality of streams of periodic samples;

each stream of periodic samples in the plurality of streams of periodic samples is phase shifted relative to every other stream of periodic samples in the plurality of streams of periodic samples;

the first periodic samples comprise a first stream of periodic samples from the plurality of streams of periodic samples;

the second periodic samples comprise a second stream of periodic samples from the plurality of streams of periodic samples.

5. The hearing aid of claim 4 , wherein:

one period of the noise signal comprises a number of samples;

the number of low-pass filters in the plurality of low-pass filters corresponds to the number of samples in one period of the noise signal.

6. The hearing aid of claim 5 , wherein

the number of low-pass filters in the plurality of low-pass filters is equal to the number of samples in one period of the noise signal.

7. The hearing aid of claim 1 , wherein:

the period of the noise signal comprises a period of a fundamental frequency of the noise signal;

the fundamental frequency comprises a value between 100 hertz and 10,000 hertz.

8. The hearing aid of claim 1 , wherein:

the input device comprises a microphone; the noise signal comprises acoustic feedback from the receiver;

the period of the noise signal corresponds to a feedback-loop delay of the hearing aid.

9. The hearing aid of claim 1 , further comprising:

a period detector configured to determine the period of the noise signal, the period comprising a fundamental frequency of the noise signal.

10. The hearing aid of claim 9 , wherein

the period detector is configured to synchronize the noise estimator with the period of the noise signal.

11. The hearing aid of claim 9 , wherein

the period detector is configured to cause the noise estimator to perform at least one of:

duplicating a sample of the first signal;

skipping a sample of the first signal; interpolating samples of the first signal.