Vocal Acoustic and Auditory-Perceptual Characteristics During Fluctuations in Estradiol Levels During the Menstrual Cycle: A Longitudinal Study.

Estradiol production varies cyclically, changes in levels are hypothesized to affect the voice. The main objective of this study was to investigate vocal acoustic and auditory-perceptual characteristics during fluctuations in the levels of the hormone estradiol during the menstrual cycle. A total of 44 volunteers aged between 18 and 45 were selected. Of these, 27 women with regular menstrual cycles comprised the test group (TG) and 17 combined oral contraceptive users comprised the control group (CG). The study was performed in two phases. In phase 1, anamnesis was performed. Subsequently, the TG underwent blood sample collection for measurement of estradiol levels and voice recording for later acoustic and auditory-perceptual analysis. The CG underwent only voice recording. Phase 2 involved the same measurements as phase 1 for each group. Variables were evaluated using descriptive and inferential analysis to compare groups and phases and to determine relationships between variables. Voice changes were found during the menstrual cycle, and such changes were determined to be related to variations in estradiol levels. Impaired voice quality was observed to be associated with decreased levels of estradiol. The CG did not demonstrate significant vocal changes during phases 1 and 2. The TG showed significant increases in vocal parameters of roughness, tension, and instability during phase 2 (the period of low estradiol levels) when compared with the CG. Low estradiol levels were also found to be negatively correlated with the parameters of tension, instability, and jitter and positively correlated with fundamental voice frequency.