The effect of initiating oral contraceptive use on voice: A case study

Objective: To examine the effects of initiating oral contraceptive (OC) use on spectrally based acoustic measures. Study Design: Case history. Methods: A 23-year-old female volunteered to participate in the study. Voice recordings were obtained during eight consecutive menstrual cycles: two cycles before the onset of OC use and six cycles after the initiation of OC use. Recordings consisted of three trials of the sustained vowel /æ/ and were obtained during the follicular phase (preovulation, days 9-11) and luteal phase (premenstruation, days 20-22) of each cycle. Measurements obtained included the following: (1) H1 - H2, the ratio of the amplitude of the first harmonic to the amplitude of the second harmonic, which correlates to closed quotient duration; (2) H1 - A1, the ratio of the amplitude of the first harmonic to the amplitude of the first formant, which correlates to glottal width; and (3) H1 - A3, the ratio of the first harmonic to the amplitude of the third formant, which correlates to the abruptness of vocal fold closure. In addition, acoustic measures of voice perturbation, jitter, shimmer, and noise-to-harmonic ratio were measured. Results: The participant exhibited changes in glottal characteristics in conjunction with initiation of OC use. Both the H1 - H2 and H1 - A1 differences changed with OC use relative to menstrual cycle phase. These two measures have been correlated with the glottal measures of closed quotient and glottal width, respectively. However, there was no significant change in the H1 - A3 difference, indicating no effect of OC use on the speed of vocal fold closure. Conclusions: The results of this study indicate that the onset of OC use can result in vocal changes as noted by different patterns of glottal adjustment across menstrual cycle phases.