The Arduino Nano interprets this data and outputs it over SPI to a DAC which outputs a signal which is then amplified and fed to the human brain courtesy of op-amps, boost converters and sponge ...

Actually getting the beats out of the Arduino required the addition of a R2R DAC circuit and a TDA2822 amplifier. In the video after the break, you can hear the results for yourself. [joekutz] is ...