The effect of increased loudness on anticipatory coarticulation of steady-state formants in a vowel-consonant-vowel context for patients with Parkinson’s disease.

Abstract

The current investigation examines the effect of increased loudness on anticipatory coarticulation of the vowels [i, ɑ, u] on the preceding schwa vowel for patients with Parkinson’s disease. Four speakers, three males and one female with speech severity levels between 8% and 49%, are involved in pre-treatment, treatment, and post-treatment conditions. During treatment, participants use an auditory device which plays speech-babble into one ear while they are speaking. The speech-babble competition results in an automatic loudness increase (Lombard effect) in the talker wearing the device. Participants produced target nonsense CVC words embedded in carrier sentences at comfortable loudness levels and at an average of 3 dB above that level. The steady-state F1, F2, and F3 formant frequencies of the preceding [ə] were analyzed to determine whether increased loudness results in increased anticipatory coarticulation from the [i, ɑ, u] vowels in the CVC words, as treatment progresses. Results using steady-state formant frequency measures from this study will be compared with previous studies that used F2 trajectory measures [Tjaden and Sussman (2006); Weismer et al. (1995); Tjaden (2003)]. (Work supported by NIH 1R01DC009409-01)