Variability of Acoustic Features of Hypernasality and it’s Assessment

Abstract

Abstract-Hypernasality (HP) is observed across voiced phonemes uttered by Cleft-Palate (CP) speakers with defective velopharyngeal (VP) opening. HP assessment using signal processing technique is challenging due to the variability of acoustic features across various conditions such as speakers, speaking style, speaking rate, severity of HP etc. Most of the study for hypernasality (HP) assessment is based on isolated sustained vowels under laboratory conditions. We measure the variability of acoustic features and detect HP using vowel /i/, /a/ and /u/ in continuous read speech with gradually increasing severity of HP of CP speakers. Linear predictive coding (LPC) method is used for acoustic feature extraction. In first part of our study, we observe the variation in acoustic parameters within and across vowel category with gradually increasing HP. We observe that inter-speaker variability in spectral features among CP subjects for vowel /i/ is 0.96, /a/ has 1.13 and vowel /u/ has 2.05. The inter-speaker variability measurement suggests that high back vowel /u/ is mostly affected and has the highest variability. High front vowel /i/ is least affected and has the lowest variability with HP. In the second part, ratio of vowel space area (VSA) of hypernasal and normal speech is calculated and used as a measure for HP detection. We observe that VSA spanned by CP subjects is 0.65 times less than isolated uttered Bangla nasal VSA and 0.43 times less than read speech uttered English oral VSA.

Static measurements of vowel formant frequencies and bandwidths: A review

“…Given the difficulty of identifying correlates of nasalization that apply across different vowels, studies often select the vowel /i/ for analysis (Haque, Ali, & Haque, 2016; Kataoka, Michi, Okabe, Miura, & Yoshida, 1996; A. S. Y. Lee, Ciocca, & Whitehill, 2003).…”

“…The clinical relevance of VSA has been noted across a spectrum of disorders affecting communication, including: (1) children with neurogenic speech disorders (Higgins & Hodge, 2002; Hustad, Gorton, & Lee, 2010; Liu, Tsao, & Kuhl, 2005; Narasimhan, Nikitha, & Francis, 2016); (2) adults with acquired dysarthria (Bang, Min, Sohn, & Cho, 2013; S. Kim, Kim, & Ko, 2014; Turner, Tjaden, & Weismer, 1995; Weismer, Jeng, Laures, Kent, & Kent, 2001); (3) adults with Down syndrome (Bunton & Leddy, 2011), (4) individuals with hearing loss (Palethorpe & Watson, 2003); (5) individuals with hearing loss (Palethorpe & Watson, 2003); (6) adults who have undergone glossectomy (Kaipa, Robb, O’Beirne, & Allison, 2012; Whitehill, Ciocca, Chan, & Samman, 2006); (7) adults who have undergone glossectomy (Kaipa, Robb, O’Beirne, & Allison, 2012; Takatsu et al 2017; Whitehill, Ciocca, Chan, & Samman, 2006); (8) individuals undergoing treatment for oral or oropharyngeal cancer (de Bruijn et al, 2009); (9) individuals with Class III malocclusion (Xue, Lam, Whitehill, & Samman, 2011); (8) people who stutter (Blomgren, Robb, & Chen, 1998; Hirsch et al, 2008); (9) individuals with hypernasality associated with cleft palate (Haque, Ali, & Haque, 2016); and (10) individuals in psychological distress or with self-reported symptoms of depression and post-traumatic stress disorder (Scherer, Lucas, Gratch, Rizzo, & Morency, in press; Scherer, Morency, Gratch, & Pestian, 2015).…”

Effect of Functional Endoscopic Sinus Surgery on Voice and Speech Recognition

“…[6][7][8][9]21 In the same sense, it is not clear if the use of other vowels would have yielded different results as some works suggest. 23 To this respect, further studies employing three repetitions of the rest of Spanish vowels must be addressed in the future. Also, the combination of traditional acoustic parameters and other new such as modulation speetrum morphological parameters 24 or complexity measurements 25 must be employed in future works.…”

Hypernasality Severity Analysis in Cleft Lip and Palate Speech Using Vowel Space Area

“…In the literature, acoustic cues such as weakening of formants, decrease in the strength and enhanced bandwidth of F1 and F2, rise in the amplitude between F1 and F2, introduction of pole/zero pairs in the vicinity of F1 and shifts in the formant frequencies are reported for the analysis of hypernasal speech [5]. Hence, these spectral modifications in the hypernasal speech will have an impact on the articulatory dynamics while producing vowels resulting in vowel centralization and in turn affecting speech intelligibility [6].…”

“…This metric has helped speech-language pathologists to study the spectral changes, the articulatory precision and found useful in predicting speech intelligibility in various speech disorders like Down syndrome [7], cerebral palsy [8], hearing impairment [9], dysarthria [10]. A recent study on VSA on CLP speakers reported the reduced vowel space in their speech [6]. However, the effect of severity of hypernasality on vowel space was not explicitly studied in the literature.…”