  Wood is one of the main materials used for making musical instruments due to
its outstanding acoustical properties. Despite such unique properties, its
inferior mechanical properties, moisture sensitivity, and time- and
cost-consuming procedure for making instruments in comparison with other
materials (e.g., composites) are always considered as its disadvantages in
making musical instruments. In this study, the acoustic parameters of three
different polyester composites separately reinforced by carbon fiber, glass
fiber, and hemp fiber are investigated and are also compared with those
obtained for three different types of wood specimens called poplar, walnut, and
beech wood, which have been extensively used in making Iranian traditional
musical instruments. The acoustical properties such as acoustic coefficient,
sound quality factor, and acoustic conversion factor were examined using some
non-destructive tests based on longitudinal and flexural free vibration and
also forced vibration methods. Furthermore, the water absorption of these
polymeric composites was compared with that of the wood samples. The results
reveal that the glass fiber-reinforced composites could be used as a suitable
alternative for some types of wood in musical applications while the carbon
fiber-reinforced composites are high performance materials to be substituted
with wood in making musical instruments showing exceptional acoustical
properties.
