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A Single DSP System for High Quality Enhancement of Diver's Speech

Daoud BERKANI, Hisham HASSANEIN, Jean-Pierre ADOUL

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Summary :

The development of saturation diving in civil and defense applications has enabled man to work in the sea at great depths and for long periods of time. This advance has resulted, in part, as a consequence of the substitution of helium for nitrogen in breathing gas mixtures. However, utilization of HeO2 breathing mixture at high ambient pressures has caused problems in speech communication; in turn, helium speech enhancement systems have been developed to improve diver communication. These speech unscramblers attempt to process variously the grossly unintelligible speech resulting from the effect of breathing mixtures and ambient pressure, and to reconstruct such signals in order to provide adequate voice communication. It is known that the glottal excitation is quasi-periodic and the vocal tract filter is quasi-stationary. Hence, it is possible to use an auto regressive modelisation to restore speech intelligibility in hyperbaric conditions. Corrections are made on the vocal tract transfer function, either in the frequency domain, or directly on the autocorrelation function. A spectral subtraction or noise reduction may be added to improve speech quality. A new VAD enhanced helium speech unscrambler is proposed for use in adverse conditions or in speech recognition. This system, implementable on single chip DSP of current technology, is capable to work in real time.

Publication
IEICE TRANSACTIONS on Fundamentals Vol.E81-A No.10 pp.2151-2158
Publication Date
1998/10/25
Publicized
Online ISSN
DOI
Type of Manuscript
Special Section PAPER (Special Section on Information Theory and Its Applications)
Category
Neural Networks/Signal Processing/Information Storage

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