OS X Yosemite - sound problems?

Thanks Etic....This worked for me...Thanks a lot mate.

This strange issue just kicked in for me yesterday. Then I had 10.10.2 on an iMac 5K with 32 gig RAM, stock SSD etc. Got this Mac in Dec 2014 as my development machine and has been performing flawlessly.

My issue is when I play audio to 'Digital Out', to my Denon AVR.

I only noticed the issue yesterday when I couldn't play mp4 videos in VLC, and started getting audio clipping of the voice; background noises are playing fine. That said, if I play Mattroska (mkv) clips with AAC, then my Denon AVR (on Digital Out/SPDIF) will switch to 'Dolby' and audio is perfect.

I have no trouble playing music through iTunes. So last night I've upgraded to 10.10.3, no luck.

Having just read this thread, I've not tried variations of killing iTunes and the coreaudiod daemon process. Rebooted multiple times. No luck at all. And now I've noticed that audio from Youtube is affected as well, via Chrome and Safari.

Thankfully, I still have my older iMac 27" (non 5K), so I may shift it back into this room and play my videos through that, hooked up to my home-theatre.

Audio through the internal speakers or attached Thunderbolt display, play just fine.

Thoughts anyone?

Wanted to chime in as I've been having this problem for several months now.

I have a MBP Retina 15" 2013 connected to a 24" Apple LED Cinema Display. Typically my sound runs through the Display, tho occasionally will use phones for sound work in Final Cut or ProTools (tho the latter runs through my MBox). Prior to the Yosemite update, I had no sound issues whatsoever, whether running from the laptop, through the display, or using multiple programs handling sound and media.

After the update, intermittently, my sound will crackle and/or to cut out depending on the program that the source is coming from. This usually occurs when I have World of Warcraft, Safari, and Mumble up and running at the same time. Each program responds to this issue differently. Generally when I notice this issue, it's because voices through Mumble become crackly, and the sound in WoW starts to warble (cut in and out rapidly that it sounds like an echo, but it's not repeating sounds). Media played in Safari will have no sound. And when adjusting volume from the keyboard, the indicator tones either are extremely delayed or do not play at all. When speaking in Mumble, no one can hear me, or my voice is distorted. Usually to regain sound, I have to quit out of all three of these programs, then restart them all. Rarely do I have to restart my whole system, but I've done that on occasion to see if I can prolong it's reoccurence. Less often, I will hear people fine through Mumble, but my voice isn't working, or is extremely distorted and I must restart Mumble and WoW. I thought it was a Mumble issue, but the issue occasionally will occur when I just have Safari and WoW open--the sound in WoW starts to warble and sounds in video in Safari won't play at all.

Unfortunately the problem is intermittent--sometimes it will not occur for a whole day or session, but other times it may happen several times back to back. Even after a full restart. But it does seem to occur more when Safari hasn't been shut down for a long time. Lately I've been trying to run WoW, Safari, and Mumble with no other programs to see if that prevents the issue, but no surefire success yet.

What's most frustrating is prior to this update, my Mac was seemingly bombproof and I could run all three plus several Adobe programs, Pro Tools, Final Cut X, etc, etc without a bobble in the system.

This thread is interesting and I'm going through the solutions one by one. I haven't checked to see if it may be an output issue, so will see if just switching sound to the laptop or headphones may clear up the issue.

Just found out more recently. If you're having the intermittent crackling sound issue with a Cinema Display, head to this thread for more info:

Sound from Thunderbolt Display crackles intermittently

Here are the three ways that I've used to clear the issue. Unfortunately it isn't a fix as it may reoccur in a few days or a few minutes.

1) Quit all running programs that have sound, especially Safari. Most times, just quitting Safari will clear up the sound a bit, but it seems I have to quit all programs to completely "reset" the sound.

2) Using SystemPrefs>Sound (or option-click on the menubar volume control) to change the output sound to go to the MBP, then setting it back to the display.

3) Unplug and re-plug the USB connector running from my display to the MBP. This forces the output sound to the MBP speakers, so doing the same as in 2. Unfortunately, sometimes the MBP won't switch the sound back to the display when it's plugged in again (which I then have to manually set).

Sorry if this has been covered already. i'm physically in pain right now.

I've been having sound issues ever since I updated to Yosemite. My latest issue came just now. I've been listening to music all day with my headphones. Randomly the volume turns down for no reason. Nothing else running, nothing else happening. It just does it.

I stepped away from my computer for about 15 minutes and when I cam back about 5 minutes ago I put my headphones on, hit play, and now my ears are ringing because the volume was all the way up. I tried to turn it down through the menu bar and nothing happened. I have to keep System Preferences opened all the time because sometimes I have to adjust the volume from there. That didn't work either, The keyboard buttons have completely stopped working.

What happened in Yosemite that I can literally NEVER predict what my sound will do? Sometime I'll adjust the volume and nothing will happen. About 5 minutes later the adjustment I made will take effect. Who's writing the code for the audio at Apple now? Why is this even an issue and why hasn't it been fixed?

I was having issues when my MacBook Pro (15in-Late 2011) running OS X 10.11.3 would output sound vi HDMI. The sound would cut in and out. Reseting PRAM(NVRAM) as described by user: joe_7399 worked.

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Resetting NVRAM

1. Shut down your Mac.
2. Locate the following keys on the keyboard: Command (⌘), Option, P, and R.
3. Turn on your Mac.
4. Press and hold the Command-Option-P-R keys immediately after you hear the startup sound.
5. Hold these keys until the computer restarts and you hear the startup sound for a second time.
6. Release the keys.

After resetting NVRAM, you may need to reconfigure settings for speaker volume, screen resolution, startup disk selection, and time zone information.

If issues related to these features continue on a desktop Mac (like an iMac, Mac mini or Mac Pro), its logic board battery may need to be replaced. The logic board battery on desktop computers helps retain NVRAM settings when your Mac is unplugged. You can take your Mac to an Apple Store or Apple Authorized Service Provider to replace the battery on the logic board.