Perception and production of voiceless plosives in electronic larynx speech

Abstract

Voiceless consonants are problematic for the electronic larynx user and the ability, or lack of it, to signal the presence of a voiceless consonant in a word may have a crucial effect on the intelligibility of the word to a normal listener. In order to determine the acoustic and perceptual properties of voiceless consonants in electronic larynx speech, recordings were made of three proficient electronic larynx users pronouncing the words tea, D, toe, doe, Kate, gate, cot, got, embedded in a frame sentence, 13 times each. Perception tests were carried out, using panels of listeners, and the results demonstrated successful identification of voiceless consonant targets at rates well above chance for the productions by all three speakers. Acoustic analysis suggested slightly different strategies on the part of the different subjects. All introduced an interval of friction noise after the closure release, and one subject employed rapid switching on and off of the device in order to create an analogue of voice-onset time. Logistic regression analysis of the relationships between the perception scores and certain acoustic features suggested that listeners were able to respond successfully to unconventional acoustic cues. The results have implications for the extent of articulatory compensation available to speakers, and for the nature of clinical speech assessment.