ORIGINAL ARTICLE Voice Low Tone to High Tone Ratio, Nasalance, and Nasality Ratings in Connected Speech of Native Mandarin Speakers: A Pilot Study Yun-Jeng Tsai, Ching-Ping Wang, M.D., Guo-She Lee, M.D., Ph.D. Objective: Voice low tone to high tone ratio (VLHR) is defined as the power ratio of a voice spectrum with a specific cut-off frequency. Previous studies have shown that there are significant correlations between VLHR and nasalance and hypernasality ratings in vowels. The correlation was investigated in this study using connected speech material. Design: The Zoo Passage, the Rainbow Passage, the English Nasal Sentences, the Mandarin Nonnasal Sentences, and the Mandarin Nasal Sentences were used to acquire VLHRs, nasalance scores, and perceptual judgments of nasality. Each passage was recorded twice for averaging, and the cut-off frequencies from 200 Hz to 1200 Hz were used to survey for the presence of optimal correlations with VLHR. Participants: Ten native Mandarin speakers with an English learning history of over 8 years were enrolled. Main outcome measures: VLHRs, nasalance scores, and hypernasality ratings. Results: The correlations of VLHR with nasalance (rho = .76, p , .001, Spearman rank correlation) and nasality ratings (rho = .81, p , .001) were significant using a cut-off frequency of 300 Hz for the English passages. For the Mandarin Sentences, the optimal correlations of VLHR with nasalance (rho = .83, p , .001) and nasality ratings (rho = .79, p , .001) were identified using a cut-off frequency of 500-Hz. Conclusion: The significant correlations of VLHR with nasalance and perceptual ratings of nasality using connected speech show that these approaches have a potential value in terms of basic and clinical application. KEY WORDS: connected speech, nasalance, nasality, Mandarin, VLHR Abnormal nasality may arise from several clinical disorders, such as hypernasality in subjects with cleft palate (Van Lierde et al., 2003), myasthenia gravis (Younger and Dickson, 1985), palatal fistula (Pinborough-Zimmerman et al., 1998), and stroke (Yorkston et al., 1989). Similarly, hyponasality occurs in patients with adenoid or tonsillar hypertrophy (Kummer et al., 1993). In addition, patients with postoperative paranasal sinusitis also have been reported to show decreased nasalance immediately after surgery and increased nasalance 1 month after surgery (Soneghet et al., 2002). Hypernasality may cause a significant reduction in speech intelligibility and usually requires intervention to improve speech intelligibility, resonance, and communication (Younger and Dickson, 1985; de Carvalho-Teles et al., 2006). Clinically, there are several parametric measurements of abnormal nasality, including nasalance, the multidimen- sional index (Van Lierde et al., 2007), and others. Nasalance is one of the common indices used to evaluate patients with a nasal resonance disorder (Fletcher, 1976). Clinically, the Nasometer is commonly used for nasalance measurement (Dalston et al., 1991). A Nasometer measures both the nasal and oral sound pressure levels of speech using a headset that contains two microphones separated by a sound-insulation plate; the process involves recording both nasal and oral sound pressure signals. The sound pressure level signals are converted to DC voltage and are linked to a computer to obtain the acoustic energy ratio that is the nasalance, which is defined as the percentage of nasal sound pressure level relative to total sound pressure level (the summation of nasal and oral sound pressure levels). A number of other similar devices to measure nasalance have also been developed, such as the NasalView (Awan, 1998) and the OroNasal Nasality System (Bundy and Zajac, 2006). The NasalView system acquires nasa- lance using headgear consisting of two separated micro- phones similar to the Nasometer system. While a bandpass filter is employed for sound acquisitions in the Nasometer Mr. Tsai is medical student, Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan. Dr. Wang is visiting staff, Department of Otolaryngology, Taichung Veterans General Hospital, Taichung, Taiwan and Lecturer, School of Medicine, Chung Shan Medical University, Taichung, Taiwan. Dr. Lee is Associate Professor, Department of Otorhinolaryngology, Faculty of Medicine, School of Medicine and Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan and Department of Otorhinolaryngology, Ren-Ai Branch, Taipei City Hospital, Taipei, Taiwan. This study was supported by the grant from National Science Council, Taiwan (NSC 99-2627-B-010-004). Submitted September 2010; Accepted May 2011. Address correspondence to: Dr. Lee, Department of Otorhinolaryn- gology, Faculty of Medicine, School of Medicine, National Yang-Ming University. No. 155, Sec. 2, Linong St., Beitou District, Taipei City 112 Taiwan. E-mail guosheli@ms12.hinet.net; gslee@ym.edu.tw. DOI: 10.1597/10-183 The Cleft Palate-Craniofacial Journal 49(4) pp. 437–446 July 2012 ’ Copyright 2012 American Cleft Palate-Craniofacial Association 437