Degrading audio quality on 24" LCD

Did you have the usb from the monitor plugged in the mac pro when you did os reinstall?

I also have this issue i have to unplug it from the USB and then plug it back in. I have a 15" MacBook Pro. I called Apple today and they told me that they didn't know how to fix it.

I have done this fix for 6 people now with sustained success.

If you upgraded to 10.5.7. with the 24" monitor's usb plugged into the computer it will cause problems. The only fix that seems to work is to reinstall the OS from disk then upgrade to 10.5.7 using the combo updater. During this process you should have nothing attached to your laptop or computer.

Matt

I have a similar sounding problem, distorted audio through the display's speaker. Disconnecting and reconnecting the USB doesn't seem to be a temporary fix and any audio coming from something using Flash simply doesn't play at all (plays fine through my MBP speakers though).

Just bought 24" cinema display last week and today (Monday) experiencing this problem too. Audio spontaneously either goes silent for some apps (eg. Skype in/out chat sound), becomes garbled for other apps (eg. FCP) or becomes oddly distorted (system volume keyboard toggle). Testing Sound Effects in Sys Prefs results in all standard sound effects sounding the same - a dull clack. Unplugging and replugging the USB connecting the display to the laptop corrects the issue temporarily. However today I have had to do that several times.

Hopefully Apple responds with an update to fix this issue.

I would like to follow up on this topic. I was working off a terbit external hard drive which had been plugged into the display usb port. I switched this to a usb port on the laptop and no longer experience the degraded audio problem. At this point the only thing I have plugged into the display is my mouse charger.

However I have been unable to resolve the issues with certain sounds. For instance, my skype chat has ceased to provide the noise for an incoming/outgoing chat. This is not something I've been able to correct with turning the program on or off or changing settings. Additionally I no longer get sound notification for incoming/outgoing mail using the Apple Mail program.

After having this monitor for almost a year and just living with the issue, I finally got around to trying to fix it. I spent about an hour on the call with Apple Support which helped eliminate some possible issues.

While I was put on hold, I did some testing and found out that the issue occurs when my USB mouse receiver is plugged into the Apple Cinema Display and I wake up the computer with the USB Mouse. If I have the receiver plugged into the Apple Cinema Display and I wake up the computer with the trackpad, everything is okay. I then moved the receiver to the macbook usb port, tried waking up the computer with the mouse and everything is OKAY.

I assume there's an issue with the communication from the cinema display to the macbook and then back to the cinema display.

I prefer not to have my receiver on my macbook if I decide to undock it, but at least it gets us closer to a solution.

It'll be interesting to see if this works for any of you.

It definitely has something to do with the USB connection. I use my LED Cinema Display with a 15" unibody Macbook Pro. I've also been experiencing this issue. It mostly manifests itself while playing World of Warcraft, and I usually plug in headphones to fix the problem, or go to system preferences and switch sound outputs. I thought this was only a World of Warcraft problem, but it manifested itself earlier today while playing a ripped copy of a movie (high throughput, about 1.37 GB file). My hypothesis is there's some issue with high throughput sound and the USB connection.

In the meantime, I'm going to try traxxed's solution and plug my Logitech mouse's receiver into the Macbook Pro directly to see if that fixes anything. I may also move my Drobo over to the Macbook Pro's firewire port, although this isn't ideal since I often use that port for my editing drive. Will post any updates if I have them.