If you're talking about the glitchy, electronic sounding distortion, then it can be fixed by switching from Multiplayer to Zombies and back(or the opposite if you're playing Zombies). It's much faster than restarting the console.
A tiger doesn't lose sleep to the opinions of sheep PSN: Spetsnaz420
This has happened to me about 10 times since the game came out. Most recently, today :(
I got this quite a few times but not recently and the first time i got it was in a zombies game and i didnt leave and my system ended up freezing and i had to have the system restore the HD. The i could still hear people on the mic though. Now I've noticed there is a new sound bug. I would play and have the music and sound effects go out but have the the voice stay on. I'm not too sure about hearing the players on the mic though. Either it cuts them off too or they weren't talking during that match. The sound went back to normal while back in the lobby but cut out the next game. At least my system didn't freeze up and had to restore the HD again.
I absolutely hate this sound glitch. It's happened to me a lot in MW3. Happened to me two days ago in BO2. I tried to tough it out and my game froze two minutes later. It's occurred about 4-5 times since I got BO2 on release day. Thanks for the tip on getting rid of it by changing the mode. I used to quit the game completely to fix it.