Acoustic analysis of the voiced-voiceless distinction in Dutch tracheoesophageal speech.

Purpose: Confusions between voiced and voiceless plosives and voiced and voiceless fricatives are common in Dutch tracheoesophageal (TE) speech. This study investigates (a) which acoustic measures are found to convey a correct voicing contrast in TE speech and (b) whether different measures are found in TE speech than in normal laryngeal (NL) speech. The main focus was on plosives. Method: Nine TE and 5 NL speakers were included in this study. Fourteen acoustic measures were selected and analyzed. Comparisons were made between voiced and voiceless for the groups separately and between TE and NL speakers. Conditional inference trees were used to establish the most important distinguishing cue. Results: TE speakers do not differ significantly from NL speakers, except for pitch-related measures. For plosives, all measures distinguished between voiced and voiceless for both speaker groups. The main distinguishing measure for the plosives was relative phonation time in the closure. Conclusions: TE and NL speakers differ less in the way the voiced-voiceless distinction is conveyed than expected. Further research is needed to show whether the main acoustic cue is also perceptually most relevant.