USE OF HARMONIC PLUS NOISE MODEL FOR REDUCTION OF SELF LEAKAGE IN ELECTROALARYNGEAL SPEECH

Artificial larynx is an assistive device for providing excitation to vocal tract as a substitute to a dysfunctional or removed larynx. The speech generated by electrolarynx, an external vibrator held against the neck tissue, is not natural and most of the time is unintelligible because of the improper shape of the excitation pulses and presence of a background noise caused by sound leakage from the vibrator. The objective of this paper is to enhance the intelligibility of electrolaryngeal speech by reducing the background noise using harmonic plus noise model (HNM). The alaryngeal speech and the leakage signal are analyzed using HNM and average harmonic spectrum of the leakage noise is subtracted from the harmonic magnitude spectrum of the noisy speech in each frame. HNM synthesis is carried out retaining the original phase spectra. Investigations show that the output is more natural and intelligible as compared to input speech signal and the enhanced signal obtained from spectral subtraction without HNM analysis and synthesis.

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