| 摘要 |
In an acoustic structure (1), sound absorbing effect is achieved by interference between incident waves falling in an opening portion (14) and reflected waves radiated from the opening as a result of resonance occurring within a hollow member in response to the incident waves, and a sound absorbing region is formed, for example, in a frontal direction of the opening portion. Sound scattering effect is achieved through interaction between the above-mentioned interference and interference between the incident waves and sound waves radiated from the opening portion, and a sound scattering region is formed, for example, near the sound absorbing region. It is deemed such a sound scattering effect is achieved by flows of motion energy of gas molecules being produced in an oblique direction, not normal to the opening portion and reflective surface, due to a phase difference between the sound waves radiated from the opening portion and the sound waves radiated from the reflective surface. Dimension, in a thickness (z) direction, of the acoustic structure is sufficiently small as compared to a wavelength of a resonant frequency, and thus, the acoustic structure would not greatly narrow an installation space. |
