Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Investigating the acoustical properties of carbon fiber-, glass fiber-,
  and hemp fiber-reinforced polyester composites   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.

3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph