Testosterone therapy is considered standard of care medical treatment for transgender and gender diverse individuals assigned female at birth. The impact of gender affirming testosterone therapy on respiratory muscle strength has not yet been studied, nor have respiratory norms for transgender and gender diverse individuals undergoing this therapy been established. In considering voice for this population, establishing respiratory norms would aid the accuracy of pulmonary function testing for individuals who have undergone testosterone therapy and provide data to the limited pool of evidence on the vocal effects of testosterone therapy. The purpose of this pilot study was to explore the effect of testosterone therapy as part of medical treatment to align gender identity, on respiration and voice production, highlighting the need for larger studies to establish norms and better inform patients on possible respiratory changes post-treatment.