Physiological Responses to an Experimental Vocal Demand Task and Immediate Effects of Recovery Interventions Across...

To examine whether experimentally increasing vocal demand with a Vocal Loading Task (VLT) elicits a coordinated vocal demand response across multiple physiological domains and whether this response is differentially modulated by immediate recovery interventions.

This study was designed as a prospective, repeated-measures crossover study. Twenty-nine normophonic female participants (age range: 18-25 years) completed a 1-hour VLT across four sessions (48-hour intervals), each followed by one of four interventions: transcutaneous electrical nerve stimulation (TENS), therapeutic ultrasound (US), semi-occluded vocal tract exercises (SOVTE), or vocal rest. Assessments at baseline (T0), post loading (T1), and post intervention (T2) included perceived vocal effort, electroglottographic measures (contact quotient [CQ], fundamental frequency [Fo]), anterior neck thermography, and muscle biomechanics. Data were analyzed using a two-way repeated-measures ANOVA.

Increasing vocal demand with the VLT was associated with consistent increases in perceived effort, Fo, temperature, and muscle tone, along with decreased CQ, indicating a coordinated vocal demand response across multiple physiological domains. All interventions reduced perceived effort, TENS and US produced greater reductions than SOVTE and vocal rest. Muscle tone decreased following intervention, whereas stiffness showed limited responsiveness. CQ patterns varied by intervention, with TENS and US trending toward baseline and SOVTE associated with further decreases.

Increasing vocal demand with a VLT elicited a reproducible, multidimensional vocal demand response across perceptual, vibratory, thermal, and biomechanical domains. Recovery appeared to involve multiple, partially independent physiological processes that were differentially associated with the intervention applied. These findings support the use of multidimensional, non-invasive assessment for investigating vocal demand responses and recovery under controlled experimental conditions.