Muscle tension dysphonia (MTD) is discomfort with talking or a change in how your voice sounds caused by tightness of the muscles in and around your voice box. Muscle tension dysphonia is one of the most common causes of hoarseness and affects people differently. Sometimes your voice can sound normal and then it can suddenly change. The condition can make your voice sound tight, rough, or weak, but may cause other symptoms such as becoming tired while talking, needing to work harder to talk, or feeling soreness with talking.