Selection for low male voice pitch is generally assumed to occur because it is a valid cue of formidability, but data suggest this is wrong

Sensory Exploitation, Sexual Dimorphism, and Human Voice Pitch. David R. Feinberg, Benedict C. Jones, Marie M. Armstrong. Trends in Ecology & Evolution, https://doi.org/10.1016/j.tree.2018.09.007

Abstract: Selection for low male voice pitch is generally assumed to occur because it is a valid cue of formidability. Here we summarize recent empirical challenges to this hypothesis. We also outline an alternative account in which selection for low male voice pitch is a byproduct of sensory exploitation.

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Contrary to previous suggestions, deep male voices are no reliable indicators of "manly" attributes such as formidability, immunocompetence, or semen quality.