Why does Firefox keep going quiet?

QI use Firefox, mostly without difficulty. However, occasionally I’ll notice that one of my tabs isn’t making sounds. When that happens I can see on the tab what looks like a little speaker icon with a line through it. Closing the tab and revisiting the website in question usually fixes the problem, but I’m at a loss as to what’s causing it. There also seems to be no rhyme or reason behind it. For example, sometimes Youtube will work fine for days, but on another occasion I’ll glance at the tab and that damn speaker icon is there. It’s driving me slightly loopy, so I’d really appreciate your help. Heather Barnes

AWe think that you’re inadvertently executing a little-known keyboard shortcut that mutes the current tab. That shortcut is Control (Ctrl)+m. While it’s obviously not your intention to hit that combination, the M key is surrounded by a number of keys that, in combination with Ctrl, are shortcuts that you might use regularly.

For example, Ctrl+n opens a new browser window; Ctrl+b opens the Bookmarks bar; and Ctrl+k puts the text-entry cursor into the Search bar. One slip and you’ll mute the current tab but, as that’s not immediately obvious, it’s likely that you’ll simply repeat the shortcut you intended to perform.

So, we think that’s the cause. The solution is as simple as selecting the muted tab and pressing Ctrl+m, or right-clicking the tab and choosing Unmute Tab (see screenshot).