An innovative design for omnidirectional sound sources

A new type of omnidirectional sound source, consisting in a powerful loudsp eaker feeding a small aperture through a reverse horn for concentrating the acoustical energy, is described. The different design elements for such a source are analysed: aperture, horn, loudspeaker and cabinet, and diffracti on around the source. A simulation of the source radiation is also describe d. Measurements on the final prototype are compared to specifications and d esign. The results prove that careful design and dimensioning make it possi ble to construct a very compact omnidirectional sound source satisfying the international standards and involving only one loudspeaker. The total soun d power available is lower than with traditional omnidirectional sources (d odecahedra): 85 dB in each one-third-octave band between 100 Hz and 5 kHz, 102 dB full band. On the other hand, the directivity diagram is much smooth er.