Document Type

Patent

Patent Number

US Patent 6,577,739

Patent agency

United States Patent and Trademark Office

Publication Date

6-10-2003

Assignee

University of Iowa Research Foundation (Iowa City, IA, US)

Application Number

09/154,330

Date Filed

1998-09-16

Total Pages

9 pages

Abstract

Apparatus and methods for audio compression and frequency shifting retain the spectral shape of an audio input signal while compressing and shifting its frequency. The fast Fourier transform of the input signal is generated, to allow processing in the frequency domain. The input audio signal is divided into small time segments, and each is subjected to frequency analysis. Frequency processing includes compression and optional frequency shifting. The inverse fast Fourier transform function is performed on the compressed and frequency shifted spectrum, to compose an output audio signal, equal in duration to the original signal. The output signal is then provided to the listener with appropriate amplification to insure audible speech across the usable frequency range.

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URL

https://ir.uiowa.edu/patents/329