Sound Radiation from a Housing Containing a Vibration Source

The behaviour of the sound radiation from the plates of a housing being excited with each mode frequency has been studied theoretically and experimentally from a view point of directivity and by means of acoustical holography. The directivity is theoretically determined from the relation between the bending wavelength of a plate (λpt) and the sound wavelength in air (λair) by the use of the lattice mode of monopole sound sources. When λpt/λair is smaller than 1.0, the sound is radiated along the plate and the acoustic power is reduced. And the reported images of acoustical holography have been explained with the directivity of sound depending on λpt/λair.