Abstract: An improved method and an apparatus for reducing an undesirable characteristic of a spectral estimate of a noise signal (203) between occurrences of voice signals (202) in an input signal (117). A spectrum of the input signal (117) is estimated to produce a spectral estimate (119) of the input signal (117) including the undesirable characteristic of the noise signal (203). The spectrum of the input signal (117) is smoothed over a first bandwidth (f3-f4) during the occurrences of the voice signals (203) and over a second bandwidth (f2-f5), substantially greater than the first bandwidth (f3-f4), between the occurrences of the voice signals (203). Alternatively, the spectral estimate (119) of the input signal (117) is filtered between the occurrences of the voice signals (203).

Abstract: A radiotelephone (101) comprises a receiver (217), a transmitter (215), an attenuator (305), a loudspeaker (203) and a microphone (201). The receiver (217) receives a forward audio signal (257) on a forward signal path (256) coupled to the loudspeaker (203) for producing a first acoustic signal (263). The transmitter (215) transmits a reverse audio signal (243) generated by the microphone (201) on a reverse signal path (248). A portion of the first acoustic signal (263) is coupled to the microphone (201) for producing a feedback audio signal (337) on the reverse signal path (248). The attenuator (305) attenuates the reverse audio signal (337) responsive to a measure of the feedback audio signal (339). The measure of the feedback audio signal (339) preferably comprises a signal to noise ratio measurement of the feedback audio signal (337). The attenuator (305) is further responsive to the first audio signal (257), and an acoustic audio signal (239) which may also be coupled to the reverse signal path (248).

Abstract: An audio signal processor (209) comprises a forward signal path (256) having a forward audio signal (257) coupled to a loudspeaker (203) for producing a first acoustic signal (263), and a reverse signal path (248) coupled to a microphone (201) for producing a reverse audio signal (243), wherein at least a portion of the first acoustic signal (263) is coupled to the microphone (201) for producing a feedback audio signal (337) on the reverse signal path (248). An attenuator (305), coupled to the microphone (201), attenuates the reverse audio signal (243) responsive to a measure of the feedback audio signal (339). The measure of the feedback audio signal (339) preferrably comprises a signal to noise ratio measurement of the feedback audio signal (337). The attenuator (305) is further responsive to at least one of the first audio signal (257), and a third audio signal (239) which may also be coupled to the reverse signal path (248).

Abstract: An energy estimator (223) and method therefor decimates (401) a signal (211) to produce a decimated signal (411); rectifies (403) the decimated signal (411) to produce a full wave rectified signal (413); averages (405) the full wave rectified signal (413) over a predetermined time period to produce an averaged signal (415); applies a logarithmic function (407) to the averaged signal (415) to produce a logarithmic signal (417); and filters (409) the logarithmic signal (417) to produce an energy estimate (229) of the signal (211). The energy estimator (223) and method therefor advantageously reduces complexity while improving performance over those energy estimators of the prior art.