MacBook Pros make mild popping and beeping sounds before playing audio files

[Monday, May 19th]

Several users have reported an issue in which MacBook Pros make a few popping, hissing, or beeping sounds before and after playing some audio files.

Apple Discussions poster jsosa284 wrote:

"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."

This behavior can be rather random in occurrence, with it happening (or at least being noticeable) through the headphone jack. The sounds could possibly be from some sort of audio device initialization or shutdown routine during playback. User "NueX" on the Apple discussion boards provided a link to a recording of the sounds. The audio file plays a series of system volume change sounds (the usual "pop" sounds that accompany a volume key press) and after each there are very faint (but audible) rustling, hissing, or squealing sounds. This seems to be typical of the problem at hand.

Initially, reseting the PRAM seemed to fix this issue for some users. The PRAM contains several audio-related variables, and resetting these has solved the issue for some users. To reset the PRAM, hold down the options, command, P, and R keys at startup until the computer resets and makes the boot sound again, then release the keys and let the computer boot normally. However, further analysis revealed that this fix was not universally effective.

Similar issues? Please let us know at late-breakers@macfixit.com.

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