Spurious-sound-free measurement of parametric acoustic array using optical interferometry

When measuring a parametric acoustic array (PAA) with a microphone, the sound often suffers from so-called spurious sound, the noise generated by the nonlinearity of the microphone. This paper proposes a spurious-sound-free measurement method for a PAA using optical interferometry and Gaussian beam expansion. Comparison between the proposed method and numerical simulation by the finite element method confirmed that the proposed method measures the demodulated audio sound without any effect from spurious sound.