What Voice-Related Metrics Change With Menopause? A Systematic Review and Meta-Analysis Study

Voice complaints associated with menopause have been reported by a substantial number of studies. However, to assess the clinical relevance of menopause to voice is still difficult as the extent to which menopausal symptoms are reflected on voice metrics remains unclear. A comprehensive review and meta-analysis were carried out to identify voice-related metrics that change with menopause and to quantify the magnitude of those changes. Academic Search Premier, Medline, SciELO, Scopus, PubMed, and Web of Science were searched without restriction of publication year until January 2020. Cross-sectional studies comparing voice-related metrics between pre- and post-menopausal women were included. Studies assessing effects of hormonal-replacement therapy were excluded. Datasets with more than one publication were also disregarded. Methodological quality of included studies was assessed applying the Newcastle-Ottawa Scale for cross-sectional studies. Given the heterogeneous nature of the primary studies, random-effects models were applied to pool the estimates. Eight articles were considered eligible for meta-analyses, assessing the effects of menopause on 6 voice metrics: mean fundamental frequency (f_o), extracted from (1) speech and (2) from sustained vowel /a/; frequency perturbation measures (3) jitter, (4) shimmer and (5) noise-to-harmonics ratio; and (6) maximum phonation time. Both speech fundamental frequency and f_o for sustained vowel /a/ were found to be 0.94 and 1.18 semitones lower in post- as compared to pre-menopausal women, respectively. Although significant, the magnitude of these decreases is below the just noticeable interval difference and well above the cutting point for distinguishing female from male voices. No significant differences were found for jitter, shimmer, noise-to-harmonics ratio, and maximum phonation time. The evaluation of acoustic metrics that reflect a single aspect of voice production at a time may conceal the effects of hormonal shifts during menopause. In addition, several variables interplay during voice production and acoustical measures may constitute weak predictors of vocal folds' status, where changes associated to sex steroid hormones are most likely to occur.