Patent ID: 7430296
Filing Date: 2008-09-30
Classification: H03G

Abstract:
1. A system for reducing the dynamic range of an audio signal, comprising: a time delay that receives the audio signal and provides a time delayed audio signal; a control unit that receives the audio signal and provides a control signal indicative of whether or not the audio signal exceeds a limit; a first transformation device that transforms the time delayed audio signal from the time domain to the frequency domain and provides an input spectrum indicative thereof; a spectral processing device comprising a plurality of parallel arranged processing units that each receives the input spectrum and each applies a different dynamic compensation to the input spectrum to provide an associated one of a plurality of processor unit output signals to a selector unit that produces an output spectrum having a dynamic range that is reduced as compared to the input spectrum, where a first one of the plurality of parallel arranged processing units compares amplitude values of frequency components within the input spectrum and reduces the amplitude value of each frequency component whose value exceeds a first limit value, where a second one of the plurality of parallel arranged processing units removes frequency components that can not be perceived by a listener, and where a third one of the plurality of parallel arranged processing units performs loudness processing; a second transformation device, that receives and transforms the output spectrum from the frequency domain to the time domain and provides an output audio signal indicative thereof; and a switching unit that selectively outputs either the time delayed audio signal or the output audio signal depending upon the state of the control signal.