Sound power certification of a dodecahedron shaped sound source

7 f. :il.Reference sound sources must be stable, omnidirectional and shall present a frequency spectrum as flat as possible, within standardized limits. The reference sound sources most used on acoustic measurements are constructed as centrifugal fans that generate aerodynamic broadband noise. These sound sources are very stable due to mechanical and electrical inertia which guarantee an almost invariable rotation speed during their operation. They can be operated for long periods of time with minimum modification on their output sound power. Nevertheless, due to constructive limitations, the sound power level of aerodynamic sources is limited to approximately 95 dB(A). Even though this sound power level is enough for many laboratory and field applications, some tests require more sound power injection in reverberation rooms or on field measurements. Performance and endurance tests of electronic devices, when submitted to high sound pressure levels, and in situ sound isolation between partitions are two common examples of acoustic tests in which usual reference sound sources do not generate enough acoustic power. This paper describes a test set-up and presents some measurement results of electro-dynamic sound sources with dodecahedral shape tested in a reverberation room. The data can be used as a possible standardized procedure to evaluate this kind of sound source. Some endurance and repeatability investigation data are also presented as part of the validation tests for a 100% Brazilian made dodecahedron