Patent ID: 7742914

Claim:
A method of reducing noise in an audio signal, wherein the audio signal comprises spectral components, comprising the steps of: (a) using a furrow filter to select spectral components that are narrow in frequency but relatively broad in time; (b) using a bar filter to select spectral components that are broad in frequency but relatively narrow in time; (c) wherein there is a relative energy distribution between the output of the furrow and bar filters, analyzing the relative energy distribution between the output of the furrow and bar filters to determine the proportion of spectral components selected by each filter that will be included in an output signal; (d) reconstructing, using a processor, the audio signal based on the analysis in step (c) above to generate the output signal; (e) wherein the furrow and bar filters are referred to as the first pair of time-frequency filters, using a second pair of time-frequency filters to improve intelligibility of the output signal; and (f) wherein the audio signal comprises fricative components, wherein the second pair of time-frequency filters comprises a furrow filter and a bar filter, wherein there is a temporal relationship between the output of the furrow filters of the first and second pairs of time-frequency filters and the output of the bar filters of the first and second pairs of time-frequency filters, monitoring the temporal relationship between the furrow filter output and the bar filter output so that the fricative components are allowed at boundaries between intervals with no voiced signal present and intervals with voice components.