Patent ID: 8315398

Claim:
A method of adjusting a loudness of an audio signal from a multi-media device to present a substantially constant perceived loudness to a listener despite loudness level changes in the audio signal, the method comprising: receiving an electronic audio signal comprising two or more channels of audio; selecting at least one of the channels of audio, said selecting comprising: determining a dominant channel of the two or more audio channels and selecting the dominant channel, wherein said determining the dominant channel comprises computing an energy value from each channel and selecting the channel with the energy value that is highest as the dominant channel; estimating a loudness of the dominant channel with one or more processors to produce an estimated loudness, said estimation comprising: processing the dominant channel with a plurality of approximation filters configured to approximate a plurality of gammatone filters, such that the plurality of approximation filters simulate a bank of auditory filters of the human ear, and weighting outputs of the approximation filters by an inverted loudness weighting curve; and computing at least one gain based at least in part on the estimated loudness to cause a perceived loudness of the audio signal to remain substantially constant for a period of time, said computing comprising: calculating a gain for a portion of the audio signal based at least partly on the estimated loudness, and smoothing the gain over a plurality of samples of the audio signal portion.