Acoustic Variability in the Healthy Female Voice Within and Across Days: How Much and Why?

Purpose The aims of this study were (1) to quantify variability in voice production (as measured acoustically) within and across consecutive days in vocally healthy female speakers, (2) to identify which acoustic measures are sensitive to this variability, and (3) to identify participant characteristics related to such voice variability. Method Participants included 45 young women with normal voices who were stratified by age, specifically 18-23, 24-29, and 30-35 years. Following an initial acoustic and auditory-perceptual voice assessment, participants performed standardized field voice recordings 3 times daily across a 7-day period. Acoustic analyses involved 32 cepstral-, spectral-, and time-based measures of connected speech and sustained vowels. Relationships among acoustic data and select demographic, health, and lifestyle (i.e., participant-based) factors were also examined. Results Significant time-of-day effects were observed for acoustic analyses within speakers (p < .05), with voices generally being worse in the morning. No significant differences were observed across consecutive days. Variations in voice production were associated with several participant factors, including improved voice with increased voice use; self-perceived poor voice function, minimal or no alcohol consumption, and extroverted personality; and worse voice with regular or current menstruation, depression, and anxiety. Conclusions This acoustic study provides essential information regarding the nature and extent to which healthy voices vary throughout the day and week. Participant-based factors that were associated with improved voice over time included increased voice use, self-perceived poor voice function, minimal or no alcohol consumption, and extroverted personality. Factors associated with worse voice production over time included regular or current menstruation, and depression and anxiety.