soph_sol, "Transgender voices: Insights on identity, embodiment, and the gender of the voice" (2018, Language and Linguistics Compass)
http://lalzimman.org/PDFs/Zimman2018TransgenderVoices.pdf
this free-to-read academic article is an overview of the features of a voice that lead people to read that voice as a particular gender
it pushes back against the traditional view of male vs female voices, of pitch being the main deciding factor in gendering voices, and of a voice's gender being immutable
it's a pretty accessible read, IMO!
16 pages in length; 12 pages if you discount the list of references