Modeling intrinsic intelligibility variation: vowel-space size and structure

This paper describes a model of talker intelligibility in read sentences, based on a variety of vowel-space and prosodic predictors. Data are analysed using mixed-effects regression, including explicit modeling of random variation due to talker, listener, and sentence. Intelligibility is found to correlate with the overall area of the vowel space, the mean area of individual vowel phonemes, and the degree of crowding or encroachment between adjacent phonemes in F2xF1 space. The relationship between talker intelligibility and the prosodic predictors tested remains unclear. The model was tested using a new set of talkers and listeners from a different dialect region, using the same set of sentences. The model did not fully generalize to the second group of talkers and listeners; however, it is argued that differences between the two groups reflect properties of the talker samples rather than genuine dialectal differences.