METHOD FOR INSTANTANEOUS PEAK LEVEL MANAGEMENT AND SPEECH CLARITY ENHANCEMENT
A method for raising the soft and mid-level amplitude of sounds for greater clarity and perceptual benefit, while simultaneously removing the high level amplitude peaks without delay and providing protection for the auditory sense organ. The method does not require a feedback mechanism for the accomplishment of this treatment and exploits the psychoacoustic phenomenon of temporal integration which reduces the audibility of short duration signals, including distortions associated with peak clipping. The human auditory system requires greater time to integrate signal energy for audibility than provided by brief duration waveform peaks.
1 . A method for improving the clarity of acoustic speech signals, comprising:
continuously measuring the average level of an input signal;
applying at least one gain value to the speech signal by a predetermined factor; and
simultaneously clipping the peak values of the input speech signal by a precalculated amount, whereby the soft high frequency unvoiced spoken components are perceptuallly enhanced.
2 . The method of claim 1 further including continuously measuring the input signal wave form amplitude and the rate of wave form amplitude change.
3 . The method of claim 2 including adjusting the speed of the clipping step in response to the measured rate of wave form amplitude change.
4 . The method of claim 3 wherein the clipping step is performed instantaneously when the rate of wave form amplitude change is less than 2.0 milliseconds.
5 . The method of claim 3 wherein the speed of the clipping step is reduced when the rate of wave form amplitude change is greater than 2.0 milliseconds.
6 . The method of claim 5 wherein the speed of the clipping step is further reduced when the rate of wave form amplitude change is greater than 2.0 seconds.
7 . The method of claim 1 wherein the range of applied gain value is between approximately 1 dB and approximately 40 dB.
8 . The method of claim 1 wherein the input signal comprises a broadband signal.
9 . The method of claim 1 wherein the input signal comprises multiple frequency band segmented signals.