Stop, approximant, and timing slot: The changing faces of the velar stop in Iwaidja

Abstract

Limited access to speakers and incomplete lexical knowledge are common challenges facing phonetic description of under-documented languages. We address these challenges by taking a multi-dimensional approach, seeking to constrain our phonetic description by covariation across acoustic and articulatory parameters. We demonstrate the approach through an analysis of velar consonsants in the Australian Aboriginal language Iwaidja. Existing accounts contrast a velar stop /k/ with a velar approximant /ɰ/ in word-medial position (Evans 2009). Converging evidence from ultrasound images of the tongue body and acoustic analysis of intensity data reveal that the posited opposition is not consistent across speakers (N = 4) and lexical items. Unsupervised categorization of the phonetic data indicates two phonetic categories, appropriately labelled as [a] and [ɰ], which do not map consistently to dictionary labels in existing descriptions. We conclude that speaker-specific allophonic variation is the result of an ongoing process of lenition of /k/ between sonorant segments which has not yet phonologized. More broadly, integrating phonetic dimensions revealed categories that were ill-defined on the basis of just acoustic or articulatory measures alone. Depth of analysis, characterized by phonetic multi-dimensionality, may support robust generalization where broad analysis (multiple speakers, large corpora) are impractical or impossible.Limited access to speakers and incomplete lexical knowledge are common challenges facing phonetic description of under-documented languages. We address these challenges by taking a multi-dimensional approach, seeking to constrain our phonetic description by covariation across acoustic and articulatory parameters. We demonstrate the approach through an analysis of velar consonsants in the Australian Aboriginal language Iwaidja. Existing accounts contrast a velar stop /k/ with a velar approximant /ɰ/ in word-medial position (Evans 2009). Converging evidence from ultrasound images of the tongue body and acoustic analysis of intensity data reveal that the posited opposition is not consistent across speakers (N = 4) and lexical items. Unsupervised categorization of the phonetic data indicates two phonetic categories, appropriately labelled as [a] and [ɰ], which do not map consistently to dictionary labels in existing descriptions. We conclude that speaker-specific allophonic variation is the result of an ongoi...