Fertility-Dependent Acoustic Variation in Women's Voices Previously Shown to Affect Listener Physiology and Perception

Longitudinal Changes in Pitch-Related Acoustic Characteristics of the Voice Throughout the Menstrual Cycle: Observational Study

Background

Identifying subtle changes in the menstrual cycle is crucial for effective fertility tracking and understanding reproductive health.

Objective

The aim of the study is to explore how fundamental frequency features vary between menstrual phases using daily voice recordings.

Methods

This study analyzed smartphone-collected voice recordings from 16 naturally cycling female participants, collected every day for 1 full menstrual cycle. Fundamental frequency features (mean, SD, 5th percentile, and 95th percentile) were extracted from each voice recording. Ovulation was estimated using luteinizing hormone urine tests taken every morning. The analysis included comparisons of these features between the follicular and luteal phases and the application of changepoint detection algorithms to assess changes and pinpoint the day in which the shifts in vocal pitch occur.

Results

The fundamental frequency SD was 9.0% (SD 2.9%) lower in the luteal phase compared to the follicular phase (95% CI 3.4%-14.7%; P=.002), and the 5th percentile of the fundamental frequency was 8.8% (SD 3.6%) higher (95% CI 1.7%-16.0%; P=.01). No significant differences were found between phases in mean fundamental frequency or the 95th percentile of the fundamental frequency (P=.65 and P=.07). Changepoint detection, applied separately to each feature, identified the point in time when vocal frequency behaviors shifted. For the fundamental frequency SD and 5th percentile, 81% (n=13) of participants exhibited shifts within the fertile window (P=.03). In comparison, only 63% (n=10; P=.24) and 50% (n=8; P=.50) of participants had shifts in the fertile window for the mean and 95th percentile of the fundamental frequency, respectively.

Conclusions

These findings indicate that subtle variations in vocal pitch may reflect changes associated with the menstrual cycle, suggesting the potential for developing a noninvasive and convenient method for monitoring reproductive health. Changepoint detection may provide a promising avenue for future work in longitudinal fertility analysis.

Voice of a woman: influence of interaction partner characteristics on cycle dependent vocal changes in women

Introduction

Research has shown that women's vocal characteristics change during the menstrual cycle. Further, evidence suggests that individuals alter their voices depending on the context, such as when speaking to a highly attractive person, or a person with a different social status. The present study aimed at investigating the degree to which women's voices change depending on the vocal characteristics of the interaction partner, and how any such changes are modulated by the woman's current menstrual cycle phase.

Methods

Forty-two naturally cycling women were recorded once during the late follicular phase (high fertility) and once during the luteal phase (low fertility) while reproducing utterances of men and women who were previously assessed to have either attractive or unattractive voices.

Results

Phonetic analyses revealed that women's voices in response to speakers changed depending on their menstrual cycle phase (F0 variation, maximum F0, Centre of gravity) and depending on the stimulus speaker's vocal attractiveness (HNR, Formants 1-3, Centre of gravity), and sex (Formant 2). Also, the vocal characteristics differed when reproducing spoken sentences of the stimulus speakers compared to when they read out written sentences (minimum F0, Formants 2-4).

Discussion

These results provide further evidence that women alter their voice depending on the vocal characteristics of the interaction partner and that these changes are modulated by the menstrual cycle phase. Specifically, the present findings suggest that cyclic shifts on women's voices may occur only in social contexts (i.e., when a putative interaction partner is involved).

Towards Predicting Menstrual Cycle Phases Exploiting Paralinguistic Features

As a growing number of people focus on understanding their bodies, the menstrual cycle and its impact on reproduction are gaining attention. Several studies have shown that the voice changes during the menstrual cycle. However, existing research primarily employs comparative analysis to detect these differences. This paper proposes using machine learning methods to analyse paralinguistic features extracted from women's voices for predicting menstrual cycle phases. We leverage available data recorded during the menstrual and late follicular phases of 44 naturally cycling women. Using eight paralinguistic features, we achieve an accuracy of 60 %, showcasing the feasibility of classifying those two phases using speech signals. We discuss implications and suggest future research avenues, such as the need to use personalised approaches.

Chemical cues of identity and reproductive status in Japanese macaques

Olfactory communication plays an important role in the regulation of socio-sexual interactions in mammals. There is growing evidence that both human and nonhuman primates rely on odors to inform their mating decisions. Nevertheless, studies of primate chemical ecology remain scarce due to the difficulty of obtaining and analyzing samples. We analyzed 67 urine samples from five captive female Japanese macaques (Macaca fuscata) and 30 vaginal swabs from three of these females using gas chromatography-mass spectrometry and examined the relationship between odor (compounds identified, richness, intensity, and diversity) and female identity as well as cycle phase. We found a total of 36 urine compounds of which we identified 31, and 68 vaginal compounds of which we identified 37. Our results suggest that urine and vaginal odor varied more between individuals than within cycle phases. However, we found that within a female cycle, urine samples from similar phases may cluster more than samples from different phases. Our results suggest that female odor may encode information about identity (vaginal and urine odor) and reproductive status (urine odor). The question of how conspecifics use female urine and vaginal odor remains open and could be tested using bioassays. Our results and their interpretation are constrained by our limited sample size and our study design. Nonetheless, our study provides insight into the potential signaling role of female odor in sexual communication in Japanese macaques and contributes to our understanding of how odors may influence mating strategies in primates.