Influence of /r/ on burst spectra for stop place

Abstract

Bilabial and lingua-alveolar stops in 20 minimally contrastive word pairs in both singleton and stop /r/ (cluster) contexts were recorded from two girls, one with facial paralysis (CFP) and one with normal facial movement (CNM). Auditory identification of these productions by 12 listeners revealed a significant place by context interaction for CFP. Identification scores were high for her lingua-alveolar stops (99.3% singletons; 94.8% clusters). Identification scores for her bilabial stops were lower, with singletons being significantly lower (57.8%) than clusters (77.8%). Acoustic cues for stop place (F2 onset frequency, VOT, mean and skewness of burst spectra) were measured for all word productions. For both girls, F2 onset and VOT measures were lower for bilabial than lingua alveolar stops in singletons and clusters. CFP’s burst spectra for bilabials had a higher mean and more negative skewness than lingua alveolars in singletons and clusters. CNM’s burst spectra for bilabials had a lower mean and more positive skewness than lingua alveolars in singletons (expected) but a higher mean and more negative skewness for bilabials than lingua alveolars in clusters (unexpected). This unexpected finding may account for CFP’s higher identification rates for bilabial clusters (all acoustic cues ‘‘fit’’ those of a child with normal facial movement).