Experienced and Inexperienced Listeners' Perception of Vocal Strain

Objective: The ability to perceive strain or tension in a voice is critical for both speech-language pathologists and singing teachers. Research on voice quality has focused primarily on the perception of breathiness or roughness. The perception of vocal strain has not been extensively researched and is poorly understood.

Methods/design: This study employs a group and a within-subject design. Synthetic female sung stimuli were created that varied in source slope and vocal tract transfer function. Two groups of listeners, inexperienced listeners and experienced vocal pedagogues, listened to the stimuli and rated the perceived strain using a visual analog scale Synthetic female stimuli were constructed on the vowel /ɑ/ at 2 pitches, A3 and F5, using glottal source slopes that drop in amplitude at constant rates varying from - 6 dB/octave to - 18 dB/octave. All stimuli were filtered using three vocal tract transfer functions, one derived from a lyric/coloratura soprano, one derived from a mezzo-soprano, and a third that has resonance frequencies mid-way between the two. Listeners heard the stimuli over headphones and rated them on a scale from "no strain" to "very strained" using a visual-analog scale.

Results: Spectral source slope was strongly related to the perception of strain in both groups of listeners. Experienced listeners' perception of strain was also related to formant pattern, while inexperienced listeners' perception of strain was also related to pitch.

Conclusion: This study has shown that spectral source slope can be a powerful cue to the perception of strain. However, inexperienced and experienced listeners also differ from each other in how strain is perceived across speaking and singing pitches. These differences may be based on both experience and the goals of the listener.