car radio

My car radio (an Infinity in a 2011 Kia) has a weird feature where it will essentially fade in and out during silences. I'm sure this is all well and good for music, but for audiobooks, it's completely horrible. The radio cuts off phonemes from the start of words, sometimes as much as an entire syllable -- "thanks" usually comes in as "kss", for example. I remember trying a language CD years ago and the "repeat these words" section was completely unusable.

I haven't been able to find a setting on the radio to disable this, and my librarian skills are completely failing me for finding a solution. Any ideas? Do I just have to go to a car audio shop?