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Filter for Formant Tracking system

IP.com Disclosure Number: IPCOM000095834D
Original Publication Date: 1964-Aug-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Clapper, GL: AUTHOR

Abstract

The circuit is for automatically compensating formant frequency, selectors in a speech analyzing system for the frequency characteristics of the human voice. This arrangement utilizes attenuator network AN with an N-shaped characteristic, whose negative slope closely follows the falling characteristic of the voice, in the formant region between approximately 250 and 4000 cycles per second.

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Filter for Formant Tracking system

The circuit is for automatically compensating formant frequency, selectors in a speech analyzing system for the frequency characteristics of the human voice. This arrangement utilizes attenuator network AN with an N-shaped characteristic, whose negative slope closely follows the falling characteristic of the voice, in the formant region between approximately 250 and 4000 cycles per second.

Network AN is inserted between a variable frequency sine wave oscillator source and the frequency selector bank of the speech analyzer system. Hence, AN replaces the microphone and the pre-amplifier utilized when the system is actually engaged in speech analysis. In operation, a fixed output from the oscillator is automatically attenuated to simulate a human voice characteristic throughout the formant frequency range.

Input attenuators IA1... IAn for each of the frequency selectors f1F... fnF are adjusted to compensate for the voice characteristic so that a given maximum DC voltage is present at the outputs of the associated rectifiers R1... Rn. The attenuator network AN consists of suitable high-pass and low-pass filter sections of the resistance-capacitance type, having appropriate characteristics to produce a composite N-shaped frequency characteristic, as shown by the lower drawing.

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