| 摘要 |
PROBLEM TO BE SOLVED: To fully suppress standing waves by installing a sound absorber in an opening part provided on a wall and making the standing waves generated in an internal space of a cabinet due to the drive operation of a speaker to be absorbed, so that it is cancelled by tube resonance by an acoustic tube with tube length in a specified relation with the wavelength of the standing waves. SOLUTION: An acoustic tube 2 is provided along a rear plate 101b of the internal space of the cabinet 1, consisting of the rear plate 101b including a baffle plate 101a on which a speaker unit 102b is installed, a top board 101c, and a bottom board 101d. The acoustic tube 2 is provided with a hollow cross section, seals the opening 2a at a lower part by a sound-absorbing material 6, and its tube length ha is defined as approximately 1/2n of the wavelength corresponding to a lowest resonance mode of the standing waves 110, 111 to be generated in the internal space. In this case, (n) is a natural number 2 or larger, the opening part 2a is located at a nodal point between the standing waves 110, 111 and resonance waves 112, 113 are generated with tube resonance by the acoustic tube 2. Thus, the nodal point and a belly of the resonance waves are arranged in the vicinity of a nodal point, and a belly of the standing waves and the standing waves are suppressed fully.
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