Audio processing device, receiver and filtering method for filtering a useful signal and restoring it in the presence of ambient noise

摘要

An audio processing device includes an analyzer and a filter. The analyzer extracts an envelope of a noise signal and derives therefrom noise envelope parameters. The filter has coefficients which vary in response to noise envelope parameters and filters a useful signal to form a filtered signal. The coefficients are varied so that the filter enhances frequency bands of the useful signal that correspond to frequency bands of the noise signal having a higher energy than a predetermined value.