For many who has parkinson's disease, it's true. Firstly you want to hide your sickness. So you avoid social interaction. In the corner of your mind, there's a worry , that you might freeze or you may have dyskenesia. Secondly,the changes in your voice affects you. You have low voice and a soft tone. You talk very limited.
But you have to take this as a challenge. Don't be afraid to socialize. One thing you can do, SING. Singing is a speech therapy. It's an expression of feeling. Singing makes you happy.