Masculinization of the voice in transgender men is typically achieved through gender affirming hormone therapy with testosterone. However, 20% of them experience insufficient pitch decrease after 1 year testosterone use. A surgical technique to lower the pitch of the voice is the Isshiki thyroplasty type III (TP III). However, prospective studies investigating voice outcome of this surgery are completely lacking. Furthermore, the relation between the frequency parameters of the voice and the anatomical changes in the larynx is not fully understood.

The purpose of this study is to measure the short- and long-term voice outcome and outcome predictors of TP III in transgender men using a  prospective non-randomized controlled trial and a multidimensional voice assessment protocol. Secondly, a laryngeal magnetic resonance imaging protocol will be developed to measure pre- and postoperative anatomical factors and compare them with the acoustic changes.