ABSTRACT
PURPOSE: The purpose of this study was to determine the performance of normalized nasal acceleration (NNA) relative to nasalance as estimates of nasalized versus nonnasalized vowel and sentence productions. METHOD: Participants were 18 healthy speakers of American English. NNA was measured using a custom sensor, and nasalance was measured using the KayPentax Nasometer II. Speech stimuli consisted of CVC syllables with the vowels (//, /æ/, /i/, /u/) and sentences loaded with high front, high back, low front, and low back vowels in both nasal and nonnasal contexts. RESULTS: NNA showed a small but significant effect of the vowel produced during syllable stimuli but no significant effect of vowel loading during sentence stimuli. Nasalance was significantly affected by the vowel being produced during both syllables and sentences with large effect sizes. Both NNA and nasalance were highly sensitive and specific to nasalization. CONCLUSIONS: NNA was less affected by vowel than nasalance. Discrimination of nasal versus nonnasal stimuli using NNA and nasalance was comparable, suggesting potential for use of NNA for biofeedback applications. Future work to improve calibration of NNA is needed to lower intersubject variability.
Subject(s)
Nose/physiology , Phonetics , Speech Acoustics , Speech Production Measurement/instrumentation , Speech/physiology , Voice Quality/physiology , Accelerometry/instrumentation , Accelerometry/methods , Adult , Female , Humans , Male , ROC Curve , Sensitivity and Specificity , Speech Perception , Speech Production Measurement/methods , Young AdultABSTRACT
Velopharyngeal function is essential for intelligible speech production, but can often be impaired. Current clinical care could be improved with the use of reliable and objective methods of assessment appropriate for home use. This paper explores the use of a combined nasal acceleration and acoustic sensor to assess velopharyngeal function. Speech production data in nasalized and non-nasalized contexts is recorded from N=6 healthy participants and three normalization strategies are assessed. Normalizing data to maximally nasal productions results in a reduction of between-speaker variability. Using a filtered speech signal can reduce the effects of intra-speaker variability caused be differences in loudness. The normalization strategies pursued show high discriminability of nasalization in vowels with an inexpensive sensor appropriate for home use.