Voice low tone to high tone ratio: a potential quantitative index for vowel [a:] and its nasalization

• Published in: IEEE transactions on biomedical engineering Vol. 53; no. 7; pp. 1437 - 1439
• Main Authors: Guo-She Lee, Ching-Ping Wang, Yang, C.C.H., Kuo, T.B.J.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.07.2006; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adult; Air flow; Auscultation - methods; Birth disorders; Cleft Palate - classification; Cleft Palate - complications; Cleft Palate - diagnosis; Cleft Palate - physiopathology; Cutoff frequency; Diagnosis, Computer-Assisted - methods; Diseases; Female; Hospitals; Humans; Hypernasal speech; hypernasality; Male; Middle Aged; Nose - physiopathology; Phonation; Phonetics; Protocols; Respiratory Sounds; Severity of Illness Index; Signal analysis; Sound Spectrography - methods; Spectral analysis; Speech Acoustics; Speech analysis; Speech Production Measurement - methods; Temperature; Thermistors; VLHR; Voice Disorders - classification; Voice Disorders - diagnosis; Voice Disorders - etiology; Voice Disorders - physiopathology; voice spectrum
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2006.873694

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.