Effects of regional dialect on oral-nasal balance and nasality perception.

While cross-dialectal variations in nasalance have been investigated in previous studies, the influence of regional dialect on listeners' perceptual ratings of nasality has received limited research attention. This study explored cross-dialectal differences in the production of oral-nasal balance and the perception of nasality, with special emphasis on Inland North (IN) and Midland (M) dialects in the USA. Twenty-six adults representing the IN (n = 15) and M (n = 11) dialects participated in the study. Oral-nasal balance characteristics and nasality perception were compared between dialects using mean nasalance of various speech stimuli, measured via nasometry, and perceptual ratings of nasality of synthetic vowel stimuli, measured using direct magnitude estimation (DME). Despite similar mean nasalance scores between two regional dialects for standardized passage readings and sustained vowels, IN and M groups significantly differed in their perceptual ratings of nasality, with the DMEs of IN listeners being consistently and significantly higher, i.e. more nasal, than those of M listeners. Our findings provide evidence for perceptual variations of nasality that may exist at a dialectal level in addition to cross-linguistic variations in the perception of nasality as reported by Lee et al. (2008). Further research is needed to determine to what extent perceptual variations of nasality exist in other dialects and how these variations manifest in perceptual judgments of hypernasality and its severity ratings.