While we don't have our own mute button built into puzzles, we'd suggest muting sounds on individual student devices if you want your classroom to remain on the quieter side!
Most modern browsers support a "Mute Tab" option, to mute only the sounds coming from that specific tab. Check out these guides on how to mute your tab in a variety of browsers.
This won't affect any other sounds coming from your device, or if you're sharing your screen with students.