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: 
I would wager that you have Skype or some other VOIP software installed. I've encountered this same issue when using Skype. 

As soon as I launch a call in Skype it lowers my speaker volume for me automatically. Took me ages to figure out why it kept lowering. The problem was that Skype doesn't automatically set it back to what it was after a call.
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. :)