Patent ID: 8913754
Filing Date: 2014-12-16
Classification: H03G

Abstract:
1. An apparatus ( 200 ), effective in producing corrections to an audio signal which is a signal of interest, across a spectrum of frequencies, by applying corrective gains of amplitude to a plurality of frequency components which constitute the audio signal, wherein parallel compression is used to approximate gain curves derived from a psychoacoustic model, wherein the parallel compression is implemented by applying a gain G at a particular frequency component of the audio signal according to a linear compression and then combining this compressed signal with the audio signal, such that the combined parallel compression of the audio signal forms a non-linear compression curve, where the linear compression is found by the equation, G=g0+(P−T)*(1/R−1) where G is the gain in dB to be applied to the audio signal, where g0 is a makeup gain in dB, T is a threshold in dB, and R is a compression ratio, and where P is a sound intensity in dB of the audio signal at a frequency component, such that g0, T, and R are parameters that vary the shape of a resulting parallel compression curve, where the psychoacoustic model takes as inputs the audio signal loudness and an ambient noise signal loudness, where the model computes the gain in sound loudness, at a given frequency component, required to correct for the effect of the ambient noise signal, where the parameters g0, T, and R, for a plurality of noise loudness levels, are predetermined by fitting the parallel compression curves against the desired behavior, where a different set of parameters is retrieved at each instant depending on the ambient noise volume at each frequency component, where the dynamically changing noise loudness results in a dynamically changing selection of parameters for the parallel compression module, the apparatus ( 200 ) comprising: (a) a first audio device ( (b) a second audio device ( (c) the microprocessor ( i. a first frequency analysis module ( a. a linear compression module (