Acoustic emission to detect xylophagous insects in wooden musical instrument

Acoustic emission monitoring was applied for the detection of xylophagous insects and more specifically oligomerus and relative species in wooden cultural heritage musical instruments kept in European museums where the temperature and hygrometry are controlled according to International Council of Museums (ICOM) rules. Using broadband high frequency sensors [75–1000 kHz] and a high level of amplification to compensate the acoustic attenuation in wood, it is possible to detect the presence of very small larvae (1–2 mm length) in a wooden object. Different coupling materials which respect conservation rules have been tested to fix the sensor to the artefact with an optimized signal to noise ratio. Such coupling materials must not damage the surface of the object and must enable a reversible operation. Since the acoustic signal (frequency and amplitude) depends on the distance between the sensor and the source, robust data processing based on an orthogonal linear transformation is then applied to the recorded signals to distinguish insect signals from ambient noise.