Changes in voice during a day in normal voices without vocal loading

Area of Science:

• Speech and Hearing Sciences
• Acoustic Phonetics
• Voice Science

Background:

• Voice professionals, such as teachers, often experience vocal parameter changes during their workday.
• Previous research has focused on vocal changes due to vocal loading, but less is known about diurnal variations without vocal use.

Purpose of the Study:

• To investigate changes in vocal parameters (fundamental frequency, sound pressure level, and voice quality) during daytime rest in voice professionals.
• To explore potential gender differences in these diurnal vocal variations.

Main Methods:

• Eleven females and ten males recorded a standardized reading task in the forenoon and afternoon, with 6-8 hours of voice rest in between.
• Fundamental frequency (F0) and sound pressure level (SPL) were measured.
• Voice quality was assessed using the alpha ratio (high-frequency SPL/low-frequency SPL).

Main Results:

• Fundamental frequency (F0) showed a slight, non-significant increase in the afternoon for most participants.
• The alpha ratio, an indicator of voice quality, significantly increased in females and decreased in males in the afternoon.
• These diurnal vocal changes occurred despite participants avoiding voice use between recordings.

Conclusions:

• Diurnal variations in vocal parameters can occur even without vocal loading, suggesting these baseline changes should be considered in voice research.
• Observed gender differences in vocal parameter changes during rest warrant further investigation.
• The findings imply that studies on vocal loading should also account for natural daytime vocal fluctuations.