HEARING AID WITH ADAPTIVE NOISE REDUCTION AND METHOD

摘要

A method of noise reduction of low-level input signals in a hearing aid involves applying compression to the input signal using a first compression ratio if a detected measure of amplitude modulation in the input signal is below a selected modulation level, and using a second compression ratio if the measure of amplitude modulation is above the selected modulation level. This reduces the volume of low-level steady-state noise while increasing the volume of modulated signals, e.g. speech. A hearing aid having a noise reduction system (10) has means for determining a level of amplitude modulation from a noise level and an absolute average level of an input signal, and comprises a dynamic compressor having a first compression ratio and a second compression ratio. The means for determining the level of amplitude modulation is configured to control the dynamic compressor in such a way that, below a predetermined input level, unmodulated sounds are amplified less than unmodulated sounds. In this way, low-level, unmodulated sounds are dampened by the hearing aid.

主权项

1. A method of processing audio signals in a hearing aid having an acoustic input transducer, a signal processor and an output transducer, said method comprising the steps of:
splitting an input signal from the input transducer into a plurality of frequency bands, deriving an absolute average level of each frequency band of the input signal, deriving a noise level of each frequency band of the input signal, selecting an amplitude modulation level, determining a measure of amplitude modulation from the noise level and the absolute average level, in respect of each frequency band of the input signal, providing a frequency band dynamic compressor with
a first compression ratio and a first compression threshold, anda second compression ratio and a second compression threshold, and applying compression to the input signal in each frequency band using
the highest of the first and second compression ratios and the highest of the first and second compression threshold whenever the determined amplitude modulation is below the selected modulation level, andthe lowest of the first and second compression ratio and the lowest of the first and second compression threshold whenever the determined amplitude modulation is above the selected modulation level.