Acoustical-perceptual correlates of the voicing distinction for initial stops and fricatives in esophageal speech

Abstract

Tape recordings of nine esophageal and three normal speakers reading lists of stop- and fricative-initial consonant-vowel nonsense syllables were judged by eighteen listeners in a forced-choice intelligibility test. Esophageal stops and fricatives were significantly less intelligible than the normal productions. Error analysis of esophageal stops revealed 78.4% cognate voicing errors, the majority of errors occurring with voiceless stops. Measures of voice onset time (VOT) showed insufficient lag for the esophageal voiceless stops. In addition, post-burst aspiration was negligible for these voiceless stops. Burst amplitude was significantly higher for voiceless apical and velar stops than for their voiced cognates. Analysis of esophageal fricative errors revealed 59.2% cognate voicing errors. Proportion of voicing in steady state frication was calculated for all productions. Correct perception of voicing was found to be primarily a function of this measure. Using this proportion, 82% of the voicing judgments could be predicted. [This investigation was supported by NINCDS research grant no. NS 08041 and HRA predoctoral training grant no. MCT-000202-21-0.]