Materials choice and characterization

Wood is one of the best natural materials to realize strong but light structures, as musical instruments, where a low mass is required in conjunction with resistance to the high static loads induced by the strings tension. However, not all wood species are the same and very large variations are observed even within the same species. Because of this, wood characterization is a milestone in instrument making since it allows to design each part aiming at the maximum acoustic performance.

To characterize wood, as well as other orthotropic materials, three elastic and three damping measurements have to be carried out. This is a complex task that I carry out for many wood samples before choosing the right one: that who ensure the right frequency of vibration, together with a low vibrating mass.

This characterization can be performed both with mechanical and acoustical tests, similarly to what occurs with musical instruments. The measurements that one obtains have to be combined to determine a merit factor such as the radiation ratio: a figure that is proportional to the acoustic emission.