Several authors have conducted research to characterize the woods used for musical instruments. The principle of such studies is that acoustical qualities of musical instruments are linked to modal properties of the resonator, especially to the soundboard. Therefore, by knowing the mechanical parameters of materials, it is easy to deduce the frequencies of the eigen modes of a vibrating structure. Equation 1 requires only the geometrical dimension of a plate, the density, and Young's modulus to define a material:

where l is length, b is width, d is thickness, E is Young's modulus, I (= bd3/12) is inertial momentum, ρ is density, n is partial number, and fn, is frequency mode(n).

But, how do we choose the values of each parameter, since woods are variable materials with a large distribution of values-for samples coming from the same tree?