Do Phonatory Aerodynamic and Acoustic Measures in Connected Speech Differ Between Vocally Healthy Adults and Patients Diagnosed with Muscle Tension Dysphonia?

Objectives: One of the presumed etiologies of primary muscle tension dysphonia (MTD) is a respiratory-phonatory disruption resulting in poor phonatory airflow in speech; however, few data exist on the differences between vocally healthy adults and patients diagnosed with MTD. The goal of this study was to compare aerodynamic and acoustic measures of self-perceived vocally healthy adults with patients diagnosed with MTD.

Study design: Retrospective, observational, matched cohort study.

Methods: Vocally healthy adults age 19-60 years were matched on age, gender, and body mass index (BMI) to patients diagnosed with MTD. Recorded samples of the first four sentences of The Rainbow Passage were analyzed for between-group differences in the following acoustic and aerodynamic dependent measures in connected speech: mean airflow during voicing, breath number, reading passage duration, inspiratory and expiratory durations, phonation time, inspiratory and expiratory volumes, cepstral peak prominence (CPP), CPP standard deviation (CPP SD), low to high ratio (L/H ratio), L/H ratio SD, CPP Fo, CPP Fo SD, cepstral spectral index of dysphonia, and dB sound pressure level (SPL).

Results: One hundred and seventy participants were studied; 85 patients diagnosed with primary MTD and 85 vocally healthy control participants. The two groups differed significantly in mean SPL, duration of the reading passage, and inspiratory and expiratory airflow duration (P ≤ 0.003). No significant differences were observed between the groups on any other phonatory aerodynamic or acoustic measure. Mean SPL, duration of the reading passage, and inspiratory and expiratory airflow durations were lower and longer, respectively, in patients with MTD. Ranges and standard deviations were greater for all aerodynamic and acoustic measurements in patients with MTD.

Conclusion: Large variability in aerodynamic and acoustic measurements were observed in patients with primary MTD with no salient differences at the group level compared to vocally healthy participants. Individual phonatory aerodynamic and acoustic profiles should be used when setting goals for patient treatment plans and to track response to treatment for patients with MTD. Taken in its entirety, connected speech from patients diagnosed with MTD essentially reflect normal acoustic and aerodynamic values.