  A set of 55 clarinet reeds is observed by holography, collecting 2 series of
measurements made under 2 different moisture contents, from which the resonance
frequencies of the 15 first modes are deduced. A statistical analysis of the
results reveals good correlations, but also significant differences between
both series. Within a given series, flexural modes are not strongly correlated.
A Principal Component Analysis (PCA) shows that the measurements of each series
can be described with 3 factors capturing more than $90\%$ of the variance: the
first is linked with transverse modes, the second with flexural modes of high
order and the third with the first flexural mode. A forth factor is necessary
to take into account the individual sensitivity to moisture content. Numerical
3D simulations are conducted by Finite Element Method, based on a given reed
shape and an orthotropic model. A sensitivity analysis revels that, besides the
density, the theoretical frequencies depend mainly on 2 parameters: $E_L$ and
$G_{LT}$. An approximate analytical formula is proposed to calculate the
resonance frequencies as a function of these 2 parameters. The discrepancy
between the observed frequencies and those calculated with the analytical
formula suggests that the elastic moduli of the measured reeds are frequency
dependent. A viscoelastic model is then developed, whose parameters are
computed as a linear combination from 4 orthogonal components, using a standard
least squares fitting procedure and leading to an objective characterization of
the material properties of the cane \textit{Arundo donax}.
