Mute icon keep appearing

I have 7.0.3 on my iPad model MC770B/A and for some reason when I'm reading the 'Times', the mute icon annoyingly keeps appearing in the middle of the screen. It says there for about 10 seconds before going away. My wife has the same iOS, but the smaller sized iPad and it does not happen with hers. Is there some way of preventing this from happening? (Pse don't anyone suggest that I change my newspaper.)
Thanks in advance.
M

Do you have a case on the iPad that may be interfering with the volume control?

Are you able to adjust the volume up and down ok?

Is the toggle switch on the side set to mute or orientation lock?

Mute icon

Thanks for your reply and apologies for not having responded sooner.
There is no case and the orientation switch was not set to lock.
However, I have since set the orientation to stay on landscape.
I've not noticed the problem recently and hope things are now OK.
M