multimedia keys:
F3: Previous track F4: Play/pause F5: Next track F9: Mute F10: Volume down F11: Volume up turn off: hold equal (=) and press p (for PC). turn off: hold equal (=) and press w (for windows). turn off: hold equal (=) and press m (for Mac). turn on: hold equal (=) and press n.
to see what your keys are sending:
acpi_listen