Placing a humidifier in the sound hole of your acoustic guitar counters damage caused by large shifts in humidity and keeps the playability up to par. Acoustic instruments like hollow-bodied guitars and basses as well as various other string instruments are generally more sensitive to changes in temperature and humidity than instruments like electric guitars. The unfinished and untreated wood inside the resonance chamber are particularly prone to warping of the wood. While all-solid and solid-top models run the biggest risk, it's never a bad idea to set up any laminated acoustic guitar with a purpose-made humidifier either. If you want maximum humidity-level monitoring options, then make sure to get a humidifier with a built-in hygrometer. If you're looking for a more simple solution, go for a guitar humidifier in the form of a feedback buster.
