Bottom line. We have no idea what you are hearing and calling "distorted voices" It could be anything. The only way for us to be of any real help is to actually hear and see the settings on your radio and watch you go thru and tune many stations and you provide feedback to us over the same video with sound as to the stations you are calling distorted. Even then we may not be able to pinpoint the problem.
Just rest assured that my station is not suffering from the same problem. "every other station" is NOT distorted. So if that is what you are hearing, then the problem is on your end. AND rest assured propagation is not causing these stations to sound distorted either, (artic flutter aside).
So the question becomes if you want further assistance, then you must make a youtube video of good quality with good narration from you so we can have some attempt at seeing and listening to the problem.
I will assure you this critique comes out of a real desire to help you and and also from a decades long range of experiences in helping people over a telephone to troubleshoot complex problems with electronic equipment. I would like to think I have seen and heard it all. I have found thru the years that the majority of the problems are nothing at all like the original observer has described them, and can often be found and rectified fairly easily. Even easier when I loaded my self into an automobile and actually went to the site.
I would put the ratio of problems solved per hour of troubleshooting to be about 10 to 1 comparing local live investigation vs. telephone investigation. And troubleshooting over this "glorified chat room" of this medium to be at least 10 times worse than a telephone call session. Although it is amazing sometimes the amount of correct solutions the contributors here accomplish. I wish you good luck and if you need further, you can post a youtube video or if you wish you can contact me directly. 73 James K0UA