1 Introduction 2 Spectral subtraction 3 QBNE 4 Results 5 Conclusion, & future work P.C. Pandey / EE Dept / IIT Bombay IIT Bombay Enhancement of Electrolaryngeal Speech by Reducing Leakage Noise Using Spectral Subtraction by Prem C. Pandey < [email protected] > EE Dept, IIT Bombay Electro Info Com’2007 / St Francis Inst. of Technology, Mumbai / 4-6 Jan’07
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Enhancement of Electrolaryngeal Speech by Reducing Leakage Noise Using Spectral Subtraction by
Enhancement of Electrolaryngeal Speech by Reducing Leakage Noise Using Spectral Subtraction by Prem C. Pandey < [email protected] > EE Dept, IIT Bombay Electro Info Com’2007 / St Francis Inst. of Technology, Mumbai / 4-6 Jan’07. Abstract - PowerPoint PPT Presentation
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Transcervical electrolarynx is a vibrator held against the neck tissue in order to provide excitation to the vocal tract, as a substitute to that provided by a natural larynx. It is of great help in verbal communication to a large number of laryngectomee patients. Its intelligibility suffers from the presence of a background noise, caused by leakage of the acoustic energy from the vibrator. Pitch synchronous application of spectral subtraction method, normally used for enhancement of speech corrupted by uncorrelated random noise, can be used for reduction of the self leakage noise for enhancement of electrolaryngeal speech. Average magnitude spectrum of leakage noise, obtained with lips closed, is subtracted from the magnitude spectrum of the noisy speech and the signal is reconstructed using the original phase spectrum. However, the spectrum of the leakage noise varies because of variation in the application pressure and movement of the throat tissue. A quantile based dynamic estimation of the magnitude spectrum without the need for silence/voice detection was found to be effective in noise reduction.
Drawback of averaged noise estimation during silence
● Two modes: noise estimation & speech enhancement
● Estimated noise considered stationary over entire speech enhancement mode
● Some musical & broadband noise in the output Investigations for continuous noise estimation & signal enhancement● System with voice activity detector (Berouti et al 1979)
● Without involving speech vs non-speech detection (Stahl et al 2000, Evans et al 2002, Houwu et al 2002)
Recorded and enhanced speech with (α=2,β=0.001,γ=1, Widow length=16 ms), speaker: SP, material: question-answer pair in English “What is your name? My name is santosh” using electrolarynx Servox
Recorded and enhanced speech with (α=2,β=0.001,γ=1), speaker: SP, material: question-answer pair in English “What is your name? My name is santosh” using electrolarynx NP-1, Servox, and Solatone