Evaluation of Hypernasality in Vowels Using Voice Low Tone to High Tone Ratio

• Published in: The Cleft palate-craniofacial journal Vol. 46; no. 1; pp. 47 - 52
• Main Authors: Lee, Guo-She, Wang, Ching-Ping, Fu, Sherry
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.01.2009; American Cleft Palate-Craniofacial Association; SAGE PUBLICATIONS, INC
• Subjects: Adult; Biological and medical sciences; Female; Frequency; Humans; Male; Maxillofacial surgery; Medical sciences; Middle Aged; Nasal Obstruction - diagnosis; Nasalance; Non tumoral diseases; Oral Fistula - complications; Otorhinolaryngology. Stomatology; Pharyngeal Structures; Phonation; Respiratory Tract Fistula - complications; Rhinomanometry; Sound Spectrography; Speech; Speech Acoustics; Speech/Language Therapists; Studies; Tone; Upper respiratory tract, upper alimentary tract, paranasal sinuses, salivary glands: diseases, semeiology; Velopharyngeal Insufficiency - complications; Vibration; Vocal Tract; Voice; Voice Disorders - diagnosis; Voice Disorders - etiology; Voice Quality; Vowels; Canada; hypernasality; VLHR; nasalance; velopharyngeal insufficiency; Evaluation; Nasalance; Stomatology; Communication disorder; Low; Vowel; ENT disease; Pharynx disease; Speech articulation disorder; Velopharyngeal insufficiency; Voice
• ISSN: 1055-6656; 1545-1569
• DOI: 10.1597/07-184.1

Objective: The voice low tone to high tone ratio (VLHR) is defined as the power ratio of low frequency to high frequency energy obtained by dividing the voice spectrum with a specific cutoff frequency. In a previous study, VLHR correlated significantly with nasalance and perceptual rating of hypernasality for a single vowel. The methodology was optimized in this study by investigating the correlations among other vowels. Design: Voice signals of six sustained vowels vocalized by subjects with hypernasality were collected. Vowel nasalance was obtained with a nasometer, and hypernasality rating scores were provided by two speech-language pathologists. The VLHRs calculated using different cutoff frequencies were correlated with nasalance and hypernasality rating scores. Participants: Eight subjects with hypernasality caused by palatal fistula or velopharyngeal insufficiency. Main Outcome Measures: VLHR, nasalance, and hypernasality rating score. Results: The correlation of VLHR with nasalance and hypernasality rating was most significant using a cutoff frequency of 600 Hz. The correlation of VLHR with nasalance was significant (r  =  .62, p < .01, Pearson's correlation), as was the correlation of VLHR with hypernasality score (Spearman's rank correlation coefficient  =  .62, p < .01). Conclusions: VLHR correlated significantly with nasalance and hypernasality in the six sustained vowels and may provide another quantitative index for the evaluation of hypernasality in sustained vowels.