There really isn't much you can do. It's just part of having Parkinson's. My Dad struggled with losing his ability to speak and as a salesman that was his tool al his life. Mine gets worse as the day progresses especially when i'm tired so rest becomes very important. Linda Ronstadt, Maurice White of earth,wind and fire, have both lost the ability to perform because what Parkinson's has done to their voices.

with the ST, a made a lot of exercises to improve and project my voice. I learned to use my diaphragm when I talk to another person I have to talk loud, slow, My singing voice is gone however I sing for 30 minutes every day.

Grab a glass of water and make sure you give yourself a few attempts at our best tongue twisters, to star with, try repeating some of the short ones multiple times in a row.
I tried to send some photos but could not

Try LSVT Loud. It can help a lot, but it’s not a cure.

Speech therapy may help now there is device that modulate the voice sounds similar to amplifierGo to shop devices for parkinson

I took the Loud Soft therapy and it helped. Have to keep practicing. I didnt and got soft again so i started practicing again and it helped.