I would say some of your sound files are corrupted, or possibly for some strange reason non-existent. Take a look in your San Andreas directory.
The best thing to do is find someone with the PC version of San Andreas and ask him to send you the entire SFX (I'm not sure of the name of the sound files folder, I don't have the PC version) folder, and replace that with the old SFX folder.
Other than that, it beats me. Does the game run fine?