Acoustic correlates of vocal effort: External factors and personality traits

Objectives: To develop an experimental protocol to study the vocal effort generated by introducing barriers to communication, and its relationship with certain personality traits.

Material and methods: The experimental protocol consisted of an interactive game in which the subject gave an investigator instructions to adopt various body positions (semi-directed communication situation). The Control situation included no constraints on communication. Then a Distance Constraint (increased distance between subject and investigator) and a Time Constraint (generation of performance stress by putting the subject in competition with others) were introduced. The vocal parameters studied comprised vocal intensity and fundamental frequency in the middle of the vowel of 3 target phonemes. Subjects also took the NEO FFI-R personality test.

Results: The study included 41 women aged between 18 and 52 years. Vocal intensity and fundamental frequency increased significantly with the introduction of the constraints (P<0.05), intensity passing from 75.5dB to 81.8dB and frequency from 249.4Hz to 335.8Hz. No correlations were found between these changes and results for the various personality traits.

Conclusions: This ecological protocol enables the impact of both physical and emotional obstacles to communication to be studied. No correlations between vocal effort and personality traits emerged. A larger-scale study would be necessary to analyze the continuum between vocal effort and vocal forcing, to improve speech therapy for dysfunctional dysphonia.