Photographs of the laser Doppler vibrometry experimental set-up from Coupled membranes: A mechanism of frequency filtering and transmission in the field cricket ear evidenced by micro-computed tomography, laser Doppler vibrometry, and finite element analysis

Figure S2. Laser Doppler vibrometry (LDV) recording set-up. (a) The loudspeaker, either a cone-diaphragm VISATON FR58 or a ribbon-diaphragm Heil air motion transformer (ESS), was positioned 22 cm from the cricket’s midline and 90° ipsilateral. A 1/8" precision pressure microphone (Type 4138-A-015, Brüel & Kjær) was perpendicular to the direction of the loudspeaker, and within 1 cm of the ipsilateral tympanum. The laser beam was focused from directly above. (b) The cricket was pinned to a wax bed upon a goniometer (GN1/M, Thorlabs). Posterior tympana were secured facing upwards and the anterior tympana were kept free from underlying wax by digging a tunnel in the wax beneath the tibiae. (c) The 3D laser Doppler vibrometer (MSA-100-3D, Polytec), sat upon a vibration isolation air table inside the semi-anechoic double walled audiometric room (IAC Acoustics). [Latham B, Reid A, Jackson-Camargo JC, Williams JA, Windmill JFC. Coupled membranes: A mechanism of frequency filtering and transmission in the field cricket ear evidenced by micro-computed tomography, laser Doppler vibrometry, and finite element analysis. J. R. Soc. Interface.]