This has been happening on / off for the last couple months, randomly whilst using the laptop the sound would go from normal to crackly / muffled, almost as if I was listening in rediculously low quality! I know this is the internal speakers, because headphones sound fine and it happens with every sound source (including changing volumes etc). Normally, it would stop working for only a few minutes at a time and tilting the laptop vertically or backwards would fix the problem, however, just an hour or so ago it stopped working properly and won't go back to normal. What should I do!? I'm past warranty and can't afford to repair it right now. Specs: 2011 Edition Macbook Pro, 4GB's RAM.