Dept. of Architecture, Kyoto Univ., Kyoto 606, Japan
Sound absorbing materials, which have high absorption at an arbitrary specified frequency band, are often needed in architectural acoustics. In such cases some resonator-type absorbers such as perforated boards with circular holes or slit panels with air cavities are widely used. To get high absorption at not only specific (resonant) but also other frequencies by such panels some porous material like fiberglass may also be filled in the air cavity. This work shows experimentally that rigid slit panels with partitioned air cavities of a few different shaped sections (which is called as complex slit panel) have high absorption at a broad (ranged two or three octaves) frequency band without any other absorbing material. According to measurements in the reverberent chamber, complex slit panels have higher absorption than conventional slit panels consisting of identically partitioned air cavities or slit structures without partitions in the air cavity. The complex slit panels mentioned above will be made of fiber concrete and so they may be suitable as outdoor absorber because of their ease of maintenance.