The struggle with multiple voices is related to your brain's ability to filter and organize/prioritize sounds. I have never heard of a therapy that helps reduce this problem. An Audio Evoked Potential test can help a skilled neuro understand how much struggle your brain is having with audio precessing.

When I had my AEP done, the neuro looked at the results and commented. You hear everything. How do you handle that ?
To which my wife answered he doesn't. That is the problem.

Over the past 12 years, I do a bit better but not enough to not have to carry ear plugs in case I am in a situation where the sounds overwhelm me.

I wish I had a suggestion for you. Understanding how your brain struggles can be helpful as you try to avoid sounds that trigger your response.