Effect of body position on vocal tract acoustics: Acoustic pharyngometry and vowel formants

Abstract

The anatomic basis and articulatory features of speech production are often studied with imaging studies that are typically acquired in the supine body position. It is important to determine if changes in body orientation to the gravitational field alter vocal tract dimensions and speech acoustics. The purpose of this study was to assess the effect of body position (upright versus supine) on (1) oral and pharyngeal measurements derived from acoustic pharyngometry and (2) acoustic measurements of fundamental frequency (F0) and the first four formant frequencies (F1-F4) for the quadrilateral point vowels. Data were obtained for 27 male and female participants, aged 17 to 35 yrs. Acoustic pharyngometry showed a statistically significant effect of body position on volumetric measurements, with smaller values in the supine than upright position, but no changes in length measurements. Acoustic analyses of vowels showed significantly larger values in the supine than upright position for the variables of F0, F3, and the Euclidean distance from the centroid to each corner vowel in the F1-F2-F3 space. Changes in body position affected measurements of vocal tract volume but not length. Body position also affected the aforementioned acoustic variables, but the main vowel formants were preserved.

The Swallowing Profile of Healthy Aging Adults: Comparing Noninvasive Swallow Tests to Videofluoroscopic Measures of Safety and Efficiency

“…This method (also known as acoustic reflection technology) is used clinically to test the compliance of the pharynx in obstructive sleep apnea (see Viviano, 2002, for a review article). AP has also been used to quantify vocal tract measures in speech science research (Vorperian et al, 2015;Xue, Cheng, & Ng, 2010;Xue & Hao, 2003). Our previous research using magnetic resonance imaging confirms that the pharyngeal lumen expands in aging alongside reductions in muscle bulk (Molfenter et al, 2015).…”

“…With the mouthpiece in situ (lips closed, teeth resting in the guard, and tongue underneath the guard), each subject completed two oral breathing tasks, one nasal breathing task, and one modified Valsalva (breathing with vocal folds approximated to allow air escape). These breathing tasks are required for the calculation of pharyngeal volume as per published protocols (Molfenter, 2016;Vorperian et al, 2015). The measurement method is summarized here.…”

The Reliability of Oral and Pharyngeal Dimensions Captured with Acoustic Pharyngometry

“…However, post-processing of APh waveforms can be completed to quantify additional oropharyngeal tract parameters including oral length, oral volume, pharyngeal length and pharyngeal volume. While several reports of these variables have been reported in the speech science and physiology literature [6–9], none has adequately quantified reliability of the parameters. Determining the reliability of these parameters within and across raters, as well as across sessions is of paramount importance before APh in incorporated into dysphagia research.…”

“…By having participants conduct specific breathing tasks and by conducting post-processing measurement, researchers can extract oral length, oral volume, pharyngeal length and pharyngeal volume using this quick, non-invasive and inexpensive tool. Indeed, several recent studies have established normative data of these oropharyngeal tract parameters according to sex, race, body position, development and aging derived using APh [6–9]. These derived measures may have significant relevance in dysphagia research.…”

Pre‐operative voice evaluation as a hypothetical predictor of difficult laryngoscopy

“…The vocal tract – which includes the entire structure limited posteriorly by the vocal cords and anteriorly by the lips and nostrils – plays an important role in tracheal access. It is believed that alterations in the morphology of the vocal tract may consequently alter the properties of resonance, leading to alterations in some acoustic parameters of the voice . The more intense frequencies within the spectrum of voice frequencies, namely voice formants, are examples of these parameters (Fig.…”