Why are you running both chapters? This would happen if you do both chapters at the same time. And this isn't a Firefox browser issue but how the user is running both chapters at the same time.

Hi Ishan, normally when a tab is playing audio, Firefox will display a mute button on the tab. Can you spot multiple tabs playing at the same time, or is this all happening within a single tab?

If you haven't already, you could try reloading the current tab bypassing the cache with either

• Shift-click the Reload button in the toolbar
• Ctrl+Shift+R
• Ctrl+F5

This should force a full reload of the page and interrupt any background processes running in the tab.