Speaker water eject sound
Dryfy plays a special low-frequency sound that vibrates your iPhone speaker to help push out water after it gets wet. You can compare the sound before and after, test the microphone and measure the level in decibels. Microphone audio is processed only on your device and is never recorded, saved or sent.
Results vary depending on the device and how much water is inside. Sound is not a substitute for drying: see Apple's guidance on what to do if your iPhone gets wet.