Intermittent pop up on screen overlaying my work

Can you tell me how to get rid of a pop up image that keeps popping up right in the center of my screen? It is a grey, rectangular horizontal volume box with a white border; inside is a yellow "speaker" to the right of that is a full, red volume bar and to the right of that is "100 %" It appears, lasts for several minutes, then disappears, only to appear again some minutes later. Could be as little as one minute or less between appearances, and can stay for ten minutes or less. The image overlays any work I am doing (in WORD for example) or any internet site I may be on. It doesn't interfere with my ability to type behind it - but obviously, when I do, I cannot see anything that I am typing until I am out of range of the image. It does not appear to be connected with my microsoft PC controls in anyway. I use Windows 10. If there was a way to post a photo of it I would do so, but it doesn't look like there is. Thank you.