Voice quality types and uses in North American English.

Voice quality has been defined variously in the literature ranging from states or postures of the glottis and vocal tract in general most broadly, to a narrower definition which refers to characteristics of vocal fold vibration during voiced phonation. Linguists have traditionally broken the voicing continuum into five basic categories based on roles they play in a language's phonology: (spread) voiceless, breathy, modal, creaky, (constricted) voiceless. Of these, the three central states, breathy, modal, creaky, are relevant to voice quality as discussed in this work. Voice qualities can be modelled as an interaction between subglottal pressure, degree of vocal fold approximation (aperture), longitudinal tension of the vocal folds (stiffness), and medial compression of the vocal folds (thickness). Breathy voicing is achieved with high glottal aperture, low stiffness, and low thickness, resulting in noise, low pitch, and increased spectral tilt. Creaky voicing has differing realizations depending on its linguistic role, prototypical creaky voice has low aperture, low stiffness, and high thickness, resulting in irregular and lower pitch, and decreased spectral tilt. Several other types of creaky voice quality exist including: 1) glottal fry, 2) multiply pulsed voice, and 3) nonconstricted creak. In this paper, we focus on creaky voice broadly-defined and concentrate on its distribution in North American English. While not contrastive, it plays an important role in phonology and a wide variety of other discourse, pragmatic, and social functions. In this context we present some of our current research into segmental and social factors relating to creaky voicing. We find a correlation between vowel height and creaky voicing. We also find evidence that voice quality is used by men to index gender in conversational speech. Our findings bear on the debate about the sociolinguistic uses of voice quality.