Bruce R Degraaf

US Patent:

62666436, Jul 24, 2001

Filed:

Mar 3, 1999

Appl. No.:

9/261496

Inventors:

Kenneth Canfield - Suffern NY
Bruce deGraaf - Northboro MA
Kathyrn deGraaf - Northboro MA

International Classification:

G10L 2104

US Classification:

704278

Abstract:

A fast and economical method for speeding up an audio signal without changing pitch can be accomplished by eliminating unneeded information from an audio signal. First, the signal is divided into chunks (frames or subframes), on which a mathematical manipulation such as a Fourier transformation is performed to identify the amplitudes of the componenet sinusoids (sines and cosines). These absolute values of the sine and cosine amplitudes for each frequency are averaged together, and the highest value(s) represents the signature, or dominant frequency/frequencies. The dominant frequency/frequencies or signatures from one chunk are compared to those of the next, and when identical the latter unit is marked as redundant. The final step consists of discarding redundant chunks from the original data, thus providing a shortened signal for replay. The pitch will not change because the only modification to the original signal was the elimination of redundant data.