Voice onset time in women as a function of oral contraceptive use.

Previous studies of the effect of hormonal changes across phases of the menstrual cycle on voice onset time (VOT) have not considered the variable of oral contraceptive use. The purpose of this study was to examine both the effects of menstrual cycle phase and that of oral contraceptive use on VOT. It was hypothesized that women taking oral contraceptives would exhibit smaller VOT differences across the phases of their menstrual cycles. The study was a prospective matched-group experimental design. Participants were 10 women who were on oral contraceptives and 10 who were not. The participants were recorded over two menstrual cycles, on the 10th and 20th day to evaluate their speech during the preovulation and premenstrual phases of their menstrual cycle. Participants produced 10 repetitions of the phrase "Speak ___ to me" containing the target syllables /bae/ and /pae/. Repeated measure ANOVAs revealed no significant differences in VOT between the two groups. Statistical results showed significant interactions between the menstrual cycle phase and the 2 recording months. It is possible that month-to-month differences in hormonal levels and other factors that can affect speech may have a greater effect on VOT than either the taking of oral contraceptives or the phase differences within a menstrual cycle.