Alteration in auditory function during the ovarian cycle.

This study investigates whether physiological variations in ovarian hormones during the ovarian cycle (OC) are associated with changes in auditory function. Sixteen women with normal hearing underwent auditory tests and simultaneous measurements of the hormone levels four times during OC. The auditory tests included recording of otoacoustic emissions (OAEs), the medial olivocochlear (MOC) suppression and auditory brainstem responses (ABRs). The OC was defined by oestradiol and progesterone serum levels and menstrual cycle dating. A significant spontaneous OAE frequency shift [F(3,114.6)=15.8, p<0.001], with the greatest shift in the late follicular phase (highest oestrogen levels), was observed. Transient evoked OAE levels showed a consistent tendency in an increase in all frequency bands in the late follicular/early luteal stage and a decrease in the late follicular stage; TEOAE inter-session comparison indicated very small statistical differences. The MOC suppression changed significantly during OC [F(3,33.8)=3.2, p=0.036], with significant inter-session difference, lower in session 2 than in session 1 (p=0.019) and lower in session 4 than in session 1 (p=0.007). The ABR wave V absolute latency changed significantly during OC [F(3,33)=3.3, p=0.03], longer in the late follicular phase. There was also a significant positive correlation of TEOAEs and ABR (wave V latency and III-V interval) and significant negative correlation of MOC suppression with oestradiol levels in the follicular phase. The results of this study reflect very small changes in auditory function during OC, and they are suggestive of an increased hearing sensitivity around the time of ovulation.