Opto-acoustic setup to detect nonlinear distortions in vibrating mechanical structures

This setup is designed to detect nonlinear distortions in the vibration of acoustically driven (bio)mechanical systems. It basically consists of a speaker (Sennheiser PMX70), a probe microphone (Bruël & Kjaer 4182), a laser vibrometer (Polytec OFV-353) and of course a test object (e.g. a latex membrane). The speaker generates an acoustic excitation signal which causes the vibration of the test object. Specially designed multisine excitation signals are used to detect the nonlinear distortions in the vibration of the test object. The acoustic input signal is measured with the probe microphone right in front of the test object, and the vibration of the test object is meausured with the vibrometer.  The described setup is used in our lab to detect the nonlinearity in the middle ear system in the acoustic frequency range.

For a detailed description:
J.R.M. Aerts, and J.J.J. Dirckx, ‘A fast full frequency range measurement of nonlinear distortions in the vibration of acoustic transducers and acoustically driven membranes’, Measurement Science and Technology 18(11): 3344-3350, 2007.
doi:10.1088/0957-0233/18/11/013