CMB 3.102V - Audio Stimuli - How to adjust researcher's audio stimuli speaker volume

If speaker is not on, the LED on the front will not be lit up.
To power on speaker, maker sure volume knob on front of speaker is turned all the way down and flip the switch on the back of the speaker.
The Front LED should be green now.
Slowly turn the knob clockwise to increase volume or counter clock wise to decreas.