Inspiratory Vocal Fry: Anatomical and Physiological Aspects, Application in Speech Therapy, Vocal Pedagogy and Singing. A Pilot study

Abstract

Objective: Inspiratory Vocal Fry (IVF) is the voice production during inspiration of a sound with vocal fry perceptual characteristics. The existing scientific literature shows a lack of studies on it. The aim of the study is to highlight anatomical and physiological characteristics of IVF, to assess its effects on spoken and singing voice, to confirm the potential usefulness in speech therapy and vocal pedagogy.

Methods: Thirty-two healthy subjects (17 male and 15 female) underwent videolaryngostroboscopy to assess the degree of false vocal folds adduction, pharyngeal wall contraction, and degree of vocal folds stretching in different types of phonation: expiratory and inspiratory phonation, Expiratory Vocal Fry (EVF) and IVF. All these parameters were evaluated by a group of three speech therapists and one phoniatrician not belonging to the research group. In addition, for each subject an electroglottography was performed for all the types of phonation previously mentioned, highlighting Contact Quotient (CQ) and Closing/Closed Quotient (CCQ). Three subjects underwent electromyography for a preliminary study of the muscle activation in IVF.

Results: False vocal folds adduction (P value = 0.000005) and pharyngeal wall contraction (P value = 0.001155) were significantly reduced in IVF compared to EVF; on the contrary, vocal folds stretching was significantly higher in IVF (P value = 0.000031). Electroglottographic CQ was significantly higher in IVF compared to EVF (P value = 0.019592) and the other types of phonation. Similar results were obtained considering CCQ, as IVF values for this parameter was significantly higher compared to EVF (P value = 0.013062) and expiratory phonation (P value = 0.001324). As regards electromyography, medial thyroarytenoid (TA) motor units were more recruited in IVF, while lateral TA motor units were more recruited in EVF. According to our results, IVF is characterized by higher elastic tension due to a reduced hypertonic contraction of TA muscle and a higher contraction of cricothyroid muscle. Electroglottographic results showed a wider vibratory cycle with an improved massaging effect on vocal folds mucosa. electromyography preliminary analysis confirmed our findings.

Conclusion: IVF could be an excellent and useful exercise to reduce muscular hypertonic tension and to facilitate mucosal elasticity. It could be potentially applied in speech therapy approach to dysfunctional and organic dysphonias, post-surgical treatment, in pedagogy and practice of artistic voice.

Keywords: Electroglottography; Electromyography; Inspiratory vocal fry; Mucosal massage.