Browse Prior Art Database

Voicing Detector

IP.com Disclosure Number: IPCOM000094581D
Original Publication Date: 1965-Mar-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Nassimbene, EG: AUTHOR

Abstract

The circuit separates voicing speech sounds from other sounds.

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Voicing Detector

The circuit separates voicing speech sounds from other sounds.

Glottal pulse detector 10 detects only true glottal pulses as opposed to plosive sounds, thus preventing most false outputs. Voicing detector 11 detects glottal pulses appearing within a narrow frequency range. High-pass filtering circuit 12 provides a continuous output level at output 13 as long as voicing continues.

The circuit produces an output within a relatively short time after the beginning of the voicing speech sounds.

Detector 10 comprises a 1,000 CPS low-pass filter 20. Its output is connected to the input of a fast charge-slow discharge circuit 21 and to a positive zero-crossing detector 22. Discharge circuit 21 is connected to a five-millisecond single-shot 23, connected to the set input of trigger 24. Detector 22 is connected to the reset input of trigger 24.

Trigger 24 is thus reset by the first positive zero-crossing and is set by the steep rise due to a glottal pulse. Therefore, the variations present on the waveform created by a plosive sound cannot give false indications as trigger 24 is not reset until the plosive sound has ceased. Since nearly all of the false outputs from the plosive sound are slope reversals located off the zero axis, detector 22 and trigger 24 eliminate such false outputs.

Voicing detector 11 comprises, along one path, trigger circuit 30. This charges capacitor 31 slowly upon receipt of a first pulse and discharges capacitor 31 at the same rate...