The INSTRUMENT 1 must be connected to a sound-generating device like iPhone, iPad, Mac, or PC. The device will receive MIDI notes from the INSTRUMENT 1 and translate them into sound. If the device is USB audio compliant (most of the above-listed platforms are), the INSTRUMENT 1 will play sound through its built-in speakers. You can optionally choose to plug in headphones or output sound from the connected device itself, bypassing the speakers on the INSTRUMENT 1.
If you see lights dashing back and forth on the fingerboard next to the capo buttons, this means that your INSTRUMENT 1 is not connected. Ensure that your mini USB cable is connecting the INSTRUMENT 1 to your iPhone, iPad, Mac, or PC.
The INSTRUMENT 1 must be selected as an audio output device in your music-making software. In iOS, swipe from the bottom of the screen to display the control center and ensure the output did not switch to a Bluetooth headset or similar.