There is also the command "/mountbgm". You can place the command in a macro and place that macro on your hotbars, letting you toggle mount music on and off with a single button press.

Similar commands exist for all sorts of settings, like controlling whether other players' flashy battle animations are reduced or turned off entirely. All the volume settings can be controlled this way, for example:

"/mastervolume 50" sets the master volume to 50/100.

"/performsounds" toggles the sound of Bards using their instruments on and off.

There's a full dictionary of chat commands on the website. Set up a few macros for yourself and you'll be able to flip between HUD setups, reduce battle effects and customise your volume settings on the fly.