Dynamic features of vocal folds based on speech production model for detection of stressed speech

Voice Stress Analysis: A New Framework for Voice and Effort in Human Performance

“…During phonation, stress increases the tension of the cricothyroid muscle and intensifies subglottal pressure ( Zhou et al, 2001 ). As mentioned above, increased tension of the cricothyroid muscle impacts the frequency of vocal fold vibration ( Kreiman and Sidtis, 2011 ; Zhang, 2015 ) whereas increased subglottal pressure has an impact on the vocal loudness ( Herbst et al, 2015 ; Zhang, 2015 ; Yao et al, 2016 ; Sundberg, 2017 ). As said, periodic vocal fold vibration is measured by the fundamental frequency or so called F0 of a sound which directly expresses the number of cycles per second (Hz) of a sound wave.…”

“…Other techniques for voice inconsistencies or noise in the voice are jitter (i.e., short-term changes in period length) and shimmer (i.e., short-term changes in amplitude) (e.g., Clark and Yallop, 1990 ; Dietrich and Abbott, 2012 ; Boersma and Weenink, 2013 ). When related to stress, jitter and shimmer are the result of either small variations or asymmetries in the cricothyroid muscle tension ( Brenner and Shipp, 1988 ) and/or fluctuations in subglottal pressure ( Yao et al, 2016 ) and/or perturbations in the mucous of the vocal folds ( Higgins and Saxman, 1989 ; Kreiman and Sidtis, 2011 ). Both for jitter and shimmer, there are standard norm values and a threshold of pathology based on the ratios of averaged differences in rate (jitter) or amplitude (shimmer) of consecutive periods divided by the average rate or amplitude ( Boersma and Weenink, 2013 ).…”

“…During phonation, stress can also induce small variations or asymmetries in the tension of the cricothyroid muscle ( Brenner and Shipp, 1988 ) and/or fluctuations in subglottal pressure ( Yao et al, 2016 ). These voice inconsistencies or ‘noise’ in the voice are measured in terms of jitter, shimmer, SNR/HNR reactivity and HRF (e.g., Clark and Yallop, 1990 ; Dietrich and Abbott, 2012 ; Boersma and Weenink, 2013 ) and are sometimes descriptively referred to as ‘hoarseness’ (e.g., Protopapas and Lieberman, 1997 , p. 2267; Postma-Nilsenová et al, 2016 , p. 1349).…”

“…In the above described top-down/bottom-up equilibration during stress exposure, the impact of some physiological characteristics should be taken into account when studying voice stress factors, certainly in real-life urgency circumstances where increased F0 and vocal loudness are common speech factors. As explained in the introduction, they are both related with subglottal pressure (we refer the interested reader to Herbst et al, 2015 ; Zhang, 2015 ; Yao et al, 2016 ; Sundberg, 2017 ). Moreover, also the chosen speech phonation type or degree of glottal adduction is related with both subglottal pressure ( Herbst et al, 2015 ) and NAQ ( Godin and Hansen, 2015 ).…”

“…To allow this vibration, phonation requires a balance between subglottal pressure (i.e., the pressure of the airflow below the glottis or space between the vocal folds) and the tension, stiffness, vocal fold approximation and resistance of the vocal folds (for an extensive explanation on the connectedness of each of these vocal fold processes and the respective muscles, see Zhang, 2015 ); a balance that is in general obtained by means of respiratory regulation with the aid of the abdominal muscles throughout the expiratory phase of speech breathing ( Hixon et al, 1976 ) and laryngeal regulation by vocal fold adduction ( Herbst et al, 2015 ; Zhang, 2015 ). Within this process, subglottal pressure determines vocal loudness whereas the adduction of the cricothyroid muscle impacts the F0 of the vocal source ( Herbst et al, 2015 ; Zhang, 2015 ; Yao et al, 2016 ; Sundberg, 2017 ). When a balance is achieved, a relatively small glottal opening and low airflow that nevertheless is able to overcome the resistance, can be preserved.…”