Testosterone causes the voice to deepen and change significantly through its direct effects on the vocal cords and surrounding structures. Research shows that when someone starts testosterone therapy, their voice will gradually drop in pitch as the hormone stimulates growth and thickening of the vocal cords, similar to what happens during male puberty.
Evidence indicates that voice changes typically begin within the first few months of starting hormone therapy and continue to develop over the first year or two of treatment. The larynx grows larger, the vocal cords become longer and thicker, and the resonating spaces in the throat expand. These changes are considered irreversible, meaning the voice will remain deeper even if testosterone therapy is discontinued later.
Guidelines recommend that people considering testosterone therapy understand this is one of the most noticeable effects of treatment. For trans men and non-binary people assigned female at birth, voice deepening is often particularly affirming as it helps align their vocal presentation with their gender identity. Voice coaching alongside hormone therapy can help individuals develop comfortable speaking patterns as their voice changes, ensuring they feel confident with their evolving vocal range.