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Digital Realtime Pitch Extractor

IP.com Disclosure Number: IPCOM000083292D
Original Publication Date: 1974-Oct-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Esteban, D: AUTHOR [+2]

Abstract

An algorithm for achieving realtime pitch extraction by limited-length bit-pattern comparison techniques has been presented by Frei et al, in an article entitled "Adaptive Predictive Coding Based on Pitch-Controlled Interruption/Reiteration Techniques" in International Conference on Communications, Seattle, Washington, June 1973.

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Digital Realtime Pitch Extractor

An algorithm for achieving realtime pitch extraction by limited-length bit- pattern comparison techniques has been presented by Frei et al, in an article entitled "Adaptive Predictive Coding Based on Pitch-Controlled Interruption/Reiteration Techniques" in International Conference on Communications, Seattle, Washington, June 1973.

This description extends the concept to the case of PCM coded voice signals. An analog input voice signal is PCM coded in coder C and filtered in filter TF, to eliminate the adverse effects of frequency components generated by resonances within the postglottal part of the vocal tract. The output signal of filter TF is thus very close to the digital representation of the glottal wave, which would have been obtained with an accelerometer. Quadratic interpolator QI is used to increase the pitch definition, by providing interpolation points between two consecutive coded samples.

Output PCM words from QI are applied to sign detector SD and to DPCM coder CD. SD generates one bit representative of the sign of each successive PCM word, and corresponding sign bits S(i) are stored in random-access memory 1 containing 2N bit positions.

:CD also generates one bit representative of the sign of the difference between two consecutive PCM words, and the corresponding difference sign bits D(i) are stored in random-access memory 2 also containing 2N bit positions.

As explained in above-cited article by Frei et al, the nonlinear correlation a...