According to a MacFixIt article, a number of MacBook Pro users have reported that their MacBook Pro laptops make a few popping, hissing or beeping noises before and after playing certain audio files.

One testimonial went as follows:

"When I startup the computer (sound muted or not), there are two distinct pops from the left speaker (approximately 2 seconds apart. Then when the computer is on, say I press the volume up key for instance, almost simultaneously there is a pop from the left speaker. About thirty seconds afterward, there is another popping noise and I can hear a hiss from the left speaker disappearing if I put my ear right up to it."

The behavior seems to be somewhat random in occurrence and seems most noticeable through the headphone jack. One current theory is that the computer is running a form of audio device initialization or shutdown routine during playback. German user "NueX" was able to make a recording of the sounds which can be found at www.bluesalamand.de/noise.mov with the sounds being faint but audible.

Many users reported that resetting the computer's PRAM provided an initial fix for the issue, though further analysis has revealed the fix to be less than perfectly effective.

If you've seen this bug on your MacBook Pro or have any ideas as to the issue at hand, let us know over in the comments or forums.