title: Voice low tone to high tone ratio: a potential quantitative index for vowel [a:] and its nasalization.
abstract: Hypernasality is associated with various diseases and interferes with speech intelligibility. A recently developed quantitative index called voice low tone to high tone ratio (VLHR) was used to estimate nasalization. The voice spectrum is divided into low-frequency power (LFP) and high-frequency power (HFP) by a specific cutoff frequency (600 Hz). VLHR is defined as the division of LFP into HFP and is expressed in decibels. Voice signals of the sustained vowel [a :] and its nasalization in eight subjects with hypernasality were collected for analysis of nasalance and VLHR. The correlation of VLHR with nasalance scores was significant (r = 0.76, p < 0.01), and so was the correlation between VLHR and perceptual hypernasality scores (r = 0.80, p < 0.01). Simultaneous recordings of nasal airflow temperature with a thermistor and voice signals in another 8 healthy subjects showed a significant correlation between temperature rate of nasal airflow and VLHR (r = 0.76, p < 0.01), as well. We conclude that VLHR may become a potential quantitative index of hypernasal speech and can be applied in either basic or clinical studies.
authors.affiliation: Department of Otolaryngology, I-Lan Hospital, Department of Health ROC., I-Lan 260, Taiwan, ROC. guosheli@ms12.hinet.net
authors.forename: Guo-She
authors.initials: GS
authors.lastname: Lee
authors.forename: Ching-Ping
authors.initials: CP
authors.lastname: Wang
authors.forename: Cheryl C H
authors.initials: CC
authors.lastname: Yang
authors.forename: Terry B J
authors.initials: TB
authors.lastname: Kuo
mesh_terms: D000328:Adult; D001314:Auscultation / Q000379:methods*; D002972:Cleft Palate / Q000145:classification / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009666:Nose / Q000503:physiopathology*; D010699:Phonation; D010700:Phonetics; D012135:Respiratory Sounds; D012720:Severity of Illness Index; D013018:Sound Spectrography / Q000379:methods*; D013061:Speech Acoustics; D013068:Speech Production Measurement / Q000379:methods*; D014832:Voice Disorders / Q000145:classification / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*