Since I just recently got it, I know what you're talking about. I get it too.
I'm not much of a gating kinda gal, so I don't hear it too much, haha. But seriously, it's annoying, but I'm actually not too bothered by it. I first had the problem with the audio coming in and out that others had, and I got it fixed by editing the config file, so I'm so happy about that, the gating sound doesn't bother me much.
But it's easy to switch if you want to do it yourself. I did it before with the MIght and Magic games trying to fix something. If I rememeber correctly, all you do is download the newest dosbox version from the dosbox internet site, then replace the dosbox folder in the game folder with the one you downloaded, and that should be it. It would then use the new dosbox you pasted in the folderand not the olde one that is now deleted(but save a backup as with anything).