Microphone Acoustic Overload Point (AOP)
A test sequence to to measure the acoustic overload point (AOP) of a microphone.
This sequence measures the acoustic overload point (AOP) of a microphone. AOP is the SPL required to produce 10% THD @ 1kHz from the microphone’s output.
The sequence uses a 1 kHz amplitude sweep across a range of 120 dB SPL to 135 dB SPL from a calibrated source speaker. A Limit step is applied to the FSD-in value to warn the user of input clipping. The recorded time waveform is then analyzed using the HarmonicTrak algorithm to produce a Fundamental and THD vs. Level curve, both of which are shown on the final display. An intersection post processing function is applied to the THD curve to identify the level at which the curve intersects 10% THD and that level is then passed through a limit step to produce a Pass/Fail AOP verdict.