To make the music production process more creative and interesting, it’s always good to try and record your tracks in ways that are not entirely ordinary. One way to add a new, intriguing layer to any loud instruments (like amped electric guitars or drums or even horns) is to use the pickup of an acoustic guitar as a microphone – and no, you don’t need to take it apart.
Since the sound source isn’t reaching the pick up directly but reflected through the guitar’s hole, this technique will obviously create a rather dark and reverb-like sounding take of the main instrument. But also a brighter sound will be picked up: the one produced by the acoustic guitar’s strings vibrating sympathetically to the notes of the main instrument. This phenomenon is called “sympathetic resonance” and happens when passive strings respond to external vibrations of harmonic likeness – i.e. the acoustic guitar’s A or E strings will independently start vibrating when – respectively – a loud A or E note is played somewhere near. These “induced” vibrations can therefore be controlled to some degree by tuning the acoustic guitar strings to match some of the notes played by the recorded instrument – or even by tuning the snare drum or the toms to match a guitar note. When mixing, you can add this atmospheric track “behind” the main one or just use it heavily effected as an entirely new sound.