On the non-linear behaviour of ultrasonic air-borne phased arrays

•High amplitude air-borne acoustic arrays exhibit non-linear behaviour.•The non-linearity is a function of both focal height and driving amplitude.•Non-linear saturation can occur where the maximum possible acoustic pressure has been reached.•Driving arrays at higher amplitudes shows a rapidly plateauing pressure produced.•Acoustic saturation may be a suitable method of microphone calibration where the harmonics are outside of the measurement bandwidth.