Question: This is the weirdest issue I've ever encountered with my PC. Every so often, my sound will start playing back at a lower volume. This happens when watching video, listening to music, all independently.

It usually lasts anywhere up to a minute, after which it will turn up again.

The weird thing about it is that the volume control in Windows remains at 100%, even though the volume is audibly a lot lower. (No, I'm not going deaf, it's just my PC. I checked.)

I just have no idea where to go to troubleshoot this, even.

I'm using Windows 7 64-bit with an on-board Realtek sound-card.

Oh, just in case someone finds this question on Google or whatever, making sure this is on Do Nothing may fix your problem. Unfortunately, it did not work for me.

![Windows Sound dialog](https://i.stack.imgur.com/vwEgV.png)

My settings all seem fine. This is my audio slider. (Took the screenshot while the issue showed.)

![enter image description here](https://i.stack.imgur.com/1AHLD.png)

Answer: 
The main Windows volume may be 100%, but is the individual application volume still 100%?

When it happens, click the speaker in the tray and select "mixer". See if your player volume is down for some reason

![enter image description here](https://i.stack.imgur.com/DSBAE.jpg)

I also have W7 x64 and see similar behavior after making or receiving a call through Lync. I do have it muting other sounds while in a call, but it doesn't seem to go back to normal all the time after the call is finished. I usually have to go into the mixer and just click the little slider handle and the volume goes back to where it should be at that point.

If I watch the little green bar that moves when sound is coming through, it just barely blinks, but as soon as I click the slider handle it jumps up to where it should be. 

Try that the next time it happens. If the sound goes back to normal once you click the handle (not moving it, just clicking it in place) then we may have a similar issue in that some other piece of software is interfering with the individual volume control. Unfortunately, i'm still looking for a fix, but my issues is most likely Lync.

If clicking the slider doesn't work, there is a chance that your speakers themselves might be the cause. Are you using headphones? External powered speakers? You might simply try a different set of output device to rule them out.
I've got logitech Z-10 speakers, and they sometimes cause a phenomena which either turns my volume down or up, depending on which button I have pressed most recently. It seems like muting the speaker and then unmuting it fixed it.

I think it's related to Z-10 being USB speaker, and being it's own sound device, it'll affect all the devices tho. It doesn't matter if I set my TV as the default device, it'll turn the TV device volume down/up from windows as well.

Not very common solution, as not many people have the Z-10, but if you've got anything with "touch controls" as in no knobs you might wanna give it a go...

Good luck, it's really, **really** annoying. :)