Evaluation of Extremely Small Sound Source Signals Used in Speaking-Aid System with Statistical Voice Conversion

Keigo NAKAMURA  Tomoki TODA  Hiroshi SARUWATARI  Kiyohiro SHIKANO  

Publication
IEICE TRANSACTIONS on Information and Systems   Vol.E93-D   No.7   pp.1909-1917
Publication Date: 2010/07/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.E93.D.1909
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Rehabilitation Engineering and Assistive Technology
Keyword: 
laryngectomee,  speaking aid,  electrolarynx,  voice conversion,  NAM,  enhancing auditory feedback,  

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Summary: 
We have so far proposed a speaking-aid system for laryngectomees using a statistical voice conversion technique. In the proposed system, artificial speech articulated with extremely small sound source signals is detected with a Non-Audible Murmur (NAM) microphone, and then, the detected artificial speech is converted into more natural voice in a probabilistic manner. Although this system basically allows laryngectomees to speak while keeping the external source signals silent, it is still questionable how much these new sound source signals affect the converted speech quality. In this paper, we investigate the impact of various sound source signals on voice conversion accuracy. Various small sound source signals are designed by changing the spectral envelope and the waveform power independently. We conduct objective and subjective evaluations. The results of these experimental evaluations demonstrate that voice conversion accepts 1) various sound source signals with different spectral envelopes and 2) large degree of power of the sound source signals unless the power of speaking parts is almost equal to that of silence parts. Moreover, we also investigate the effectiveness of enhancing auditory feedback during speaking with the extremely small sound source signals.