STATISTICAL QUANTIFICATION OF 24-HOUR AND MONTHLY VARIABILITIES OF SPONTANEOUS OTOACOUSTIC EMISSION FREQUENCY IN HUMANS

Previous evidence has suggested a relationship between spontaneous oto acoustic emissions (SOAEs) and established, biological cycles, althoug h detailed statistical quantifications of the suggested relationships do not exist in the literature. In an attempt to statistically quantif y the purported circadian and monthly influences on this phenomenon, t wo experiments were undertaken. The first experiment was conducted ove r eight weeks, investigating 31 SOAEs recorded from eight women and tw o men. Time series statistical analysis examined whether daily, weekly , and/or monthly cycles characterized SOAE frequency variability. Resu lts yielded a significant monthly cycle for the majority of SOAEs reco rded from the women but for none of the SOAEs recorded from the men. T hese results suggest the possibility that SOAE frequency fluctuation i n women may be entrained to the monthly menstrual cycle. In the second experiment, hourly SOAE frequency stability was examined over a 24-h period to ascertain the nature of the daily frequency variation as pre cisely as possible. Four SOAEs from two subjects were examined, and ti me series analysis of these data included (1) modelling the autocorrel ation structure of the measurements, (2) resolving each 24-h series of measurements into cyclical components of various periodicities, and ( 3) testing the statistical significance of given cycles within the spe ctrum of each series. Findings included a significant 24-h variability of frequency for each SOAE, suggesting the possibility of a circadian influence on frequency fluctuation. Results from the two experiments provide quantitative evidence supporting a hypothetical relationship b etween SOAEs and established, biological cycles.