| 摘要 |
The sound board (5) comprises a wooden board (15, 16) having an elongate, approximately trapezoid shape, provided on the front face with a central longitudinal profiled string- carrier member (18) and on the reverse side with a central profiled reinforcing member or beam (20), and with two side profiled members or sound bars (19), symmetrically disposed with respect to the reinforcing beam (20). The cross-section of the reinforcing beam (20) has a central portion (20a) with an increased height or thickness (T) and two adjacent, symmetrical side portions or wings (20b) having a height or thickness which tapers gradually towards the outside through a concave arcuate profile (20c) up to a predetermined minimum value (t). The minimum value (t) of the height or thickness of the side portions or wings (20b) of the reinforcing beam (20) is comprised between 1 and 5 mm, and at least in the lower half of the reinforcing beam (20) the transverse width (w) of each of said side portions or wings (20b) of the reinforcing beam (20) is comprised between about 2/3 and 3/3 of the transverse width (W) of the central portion (20a).
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