Improvement of esophageal speech using LPC and LF model

Abstract

Esophageal speech is a restoration of speech communication in laryngectomized patient. Due to irregular pharyngoesophageal (PE) segment vibration and aerodynamic limitation, the esophageal phonation provides higher volatility of the fundamental frequency (f0) compared with laryngeal phonation. It is difficult to determine an accurate f0in esophageal speech. This paper focuses on algorithms for f0modification. Linear predictive coding (LPC) and autocorrelation function are used to calculate the f0. They are well performed in the normal case. However, the determination results of f0in esophageal speech are highly unstable without any modification of a conventional LPC technique. By proposing a smoothing technique, an accurate f0and pitch period in esophageal speech can be determined and used in LF model. Experimental results from 18 subjects suggest that average f0of esophageal phonation is lower than laryngeal phonation. The speech synthesized using this proposing technique produced better sound quality than un-processed esophageal speech. © 2006 Research Publishing Services.