Speech selective automatic gain control

Details Speech selective automatic gain control Speech selective automatic gain control

1990-12-07

1992-09-08

Shaw, Dale M.

Electrical audio signal processing systems and devices

One-way audio signal program distribution

Public address system

381 47, 381104, 395 2, G10L 302

Patent

active

051465043

ABSTRACT:
An automatic gain control circuit uses a speech recognizer to obtain smooth automatic gain control. An analog audio input signal is converted to a digital signal by an analog-to-digital converter and delayed by a delay circuit. A frame power (or alternatively, rectified peak amplitude) detector determines the power of each frame (or alternatively, the rectified peak amplitude) of the audio input signal, after applied to the A/D converter. A linear-to-log converter converts those values to a logarithmic form (for gain control over a broad range of values). A detected speech smoothing circuit smooths the variation in the values determined by the frame power (or peak amplitude) detector. A summer subtracts the output of the detected speech smoothing means from a fixed reference level, and thus obtains an error signal from the desired reference. A gain smoothing circuit smooths the resulting error signal (which is the logarithmically-shaped gain signal). A logarithm-to-linear converter converts the logarithmic gain signal to a linear form; and a multiplier multiplies the input signal by this smoothed gain. In accordance with the invention, a speech recognizer determines whether the audio input signal represents speech. An output of the speech recognizer is used to enable the detected speech smoothing circuit and the gain smoothing means when the audio input signal represents speech. Thus AGC is not used until it is required (i.e., when speech is present).

REFERENCES:
patent: 4380824 (1983-04-01), Inoue
patent: 4737976 (1988-04-01), Borth et al.
patent: 5012519 (1991-04-01), Adlersberg et al.

Affiliated with

Also associated with

Rating

Speech selective automatic gain control does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Speech selective automatic gain control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Speech selective automatic gain control will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-140189