AOP stand for Acoustic Overload Point, and AOP microphones are a type of microphone that can record in extremely noisy environment without distortion.
The acoustic overload point is the level of sound at which the microphone can no longer effectively tell the difference between the actual sound signal and noise. It no longer works effectively as a sound sensor.
Most of the time, the AOP of a microphone is considered to be reached when the distortion hits 10%, although there is no standard so that definition may vary.
With the introduction of AOP MEMS microphones, it has been possible to build smaller listening devices that support high AOP. Small microphones can be embedded in smartphones such as the LG V20, which can record sound and videos in an incredibly noisy environment such as concerts.
The demand for AOP microphones should continue to grow as users want to be able to record sound in any conditions, even the most extreme ones.