High pitched noise coming from some MacBook Pro computers

Some MacBook Pro users are noticing a high pitched ring-like noise coming from their computers, and has been described as sounding like a constant tone or like someone has turned on a TV:

Apple Discussions poster djanthonyw writes:

"It's not very loud, it's about the same as when you turn on a tv, and sounds the same too! It happens when I'm on batter and connected with the power adapter."

For some users the computer locks up and hangs for a while when the noise occurs, and for others it will come and go in a random manner. The computers dont crash, but when the noise is gone they resume functionality.

Unfortunately for now there are no known fixes, and while it's uncertain whether or not this occurrence is hardware or software based, one user attributes this to having installed 10.5.3, indicating a software problem. MacBook Pro users should be aware of this as a possibility for their computers, and if they experience the problem should attempt standard hardware and software remedies: reset the PRAM, reset the SMC, repair permissions. Additionally, audio problems that are from generated sounds could be from improper audio settings. Check the System Preferences as well as the "Audio Midi Setup" application's settings to ensure audio output is at a standard such as 44100.0Hz, 2ch-16-bit. Toggle between built-in Audio and other outputs that your computer may have, to see if some setting resets itself. Lastly, attempt removing audio-related plist files from the computer and restarting. These include:

• /Library/com.apple.audio.DeviceSettings.plist
• /Library/com.apple.audio.SystemSettings.plist
• ~/Library/com.apple.audio.AudioMIDISetup.plist

Feedback? Late-breakers@macfixit.com.

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