My voice definitely changes according to my level of l-dopa in my system. Guess I do my own therapy...sing as much as I can.When low in l-dopa, voice is lower pitch and cracks when I sing...sounds lousy. When l-dopa is a good level and I am not under any stress to perform, my voice goes back to where it was in 7th grade before my diving acccident..a very nice tone/ relaxed and a higher range. Humming at times seems to help . Making very loud Lion-type yawns. Also patting face and massaging face and neck to try to keep muscles more functional...lots of neck stretching. Got to keep everything mobile.

Regular exercise like singing is great! We have a singing group at our clinic for our PWP to get good exercise for their voices.

One important note tho, it's always a good idea to get an evaluation from a professional as there is a sensory awareness component involved in speech disorders with PD, meaning that the PWP is not always aware of the extent of changes in the voice. Getting an objective eval will help you know that you're doing everything you can do!