Patent ID: 7277554

Claim:
A hearing aid, comprising: an input signal channel providing digital input signals; an input data buffer, said input data buffer holding a block of data of size M comprised of a portion of said digital input signals; a plurality of cascaded all-pass filters comprised of 2M cascaded all-pass filters, wherein a first block of said digital input signals pass from said input data buffer through said plurality of cascaded all-pass filters to form a first sequence of delayed samples and wherein a second block of said digital input signals pass from said input data buffer through said plurality of cascaded all-pass filters to form a second sequence of delayed samples, and wherein said first sequence of delayed samples and said second sequence of delayed samples form a combined sequence of delayed samples; means for windowing a first portion of said combined sequence of delayed samples, wherein said first portion is of size M, wherein a windowed sequence of delayed samples results from said windowing means; means for applying a 2M-point frequency domain transform on said windowed sequence of delayed samples, wherein a warped sequence results from said frequency domain transform applying means; means for calculating a plurality of frequency domain level estimates of said warped sequence; means for calculating a plurality of frequency domain gain coefficients from said plurality of frequency domain level estimates; means for applying an inverse frequency domain transform on said plurality of frequency domain gain coefficients, wherein a set of compression filter coefficients of a compression gain filter result from said inverse frequency domain transform applying means; and means for convolving a second portion of said combined sequence of delayed samples with said compression filter coefficients, wherein said second portion is of size M, wherein a digital output signal results from said convolving means.