With a few jumper connections, the board will boot up in MIDI mode that will read 'classic' 31250Kbaud MIDI data on a UART pin and act like a synth/drum machine - there are dozens of built-in drum and sample effects.

Midi Example Sketch

Connect the Arduino to your computer with a USB cable and plug your headphones into the headphone jack. Select File->Examples->Adafruit_VS1053_Codec->player_miditest to load the example code for MIDI operation.. You should hear a repeating series of ascending tones from the MIDI player.