Daily Vocal Function Throughout the Menstrual Cycle: A Longitudinal Single-Subject Case Study

Objective: Previous investigations have demonstrated vocal changes corresponding with phases of the menstrual cycle, such as increased pitch during the ovulatory phase and premenstrual vocal fatigue and edema. However, few studies have explored cycle-to-cycle variations in vocal quality between and within individuals during menstruation, and to the authors’ knowledge none have looked at daily changes over multiple cycles within an individual. The purpose of this longitudinal case study was to describe the effects of the menstrual phases over multiple cycles on acoustic quality and laryngoscopic vibratory parameters of the vocal folds in a normally-cycling menstruating female.

Methods: The single participant (the lead author), is a 35-year-old female with a non-hormonal copper intrauterine device and long-standing bilateral pseudocysts with no voice complaints. Daily data collection included stroboscopic videos of sustained /i/ at habitual pitch and loudness, acoustic recordings of sustained vowels and an all-voiced sentence, vocal effort, voice use, hydration, and sleep. Cycles were divided into phases according to tracking of menses, cervical mucus, and symptomatology. Acoustic analysis was conducted via Praat and laryngeal kinematic analysis was completed using Glottis Analysis Tools.

Results: Data were analyzed by menstrual cycle day, phase based on fertile window, and phase based on estimated day of ovulation. Analysis by cycle day revealed a decrease in fundamental frequency (/a/), asymmetry quotient, and glottal gap index and an increase in smoothed cepstral peak prominence (all-voiced sentence) as the cycle progressed. Evaluation by cycle phase revealed that vocal effort was most variable during the follicular phase and increased during the luteal phase. Asymmetry quotient was greatest and closing quotient was lowest during the follicular phase, and glottis gap index was lowest in the luteal phase.

Conclusion: This case study represents a unique, longitudinal data set demonstrating inconsistent changes in vocal function across repeated menstrual cycles that will inform future investigations on the effects of hormone changes on the voice. Although our analysis revealed some trends, this study highlights the challenges of studying patterns of vocal function changes over the menstrual cycle due to high individual cycle-to-cycle variability. Future studies will include multiple participants and concurrent hormone level tracking.