Acoustic spheres consist of an external reflector and one or more speakers inside a spherical casing, achieving radiation angles of 360° horizontally and 180° vertically. These speakers guarantee uniform acoustic coverage over large surfaces.
Acoustic spheres reproduce low, mid, and high frequencies evenly (in all directions) within their 180° x 360° coverage area.
Speech intelligibility and music quality are maximized.
A diffuse sound field is created, free of harshness, distortion, or resonance. The sound is not perceived as directional.
Fewer acoustic spheres are required than conventional loudspeakers for the same space.
Uniform diffusion is achieved above a certain minimum height (~4 m). The acoustic spheres are installed in the center of the room, suspended from the ceiling. If several are needed, they are distributed so that they cover an equal area.
The number of spheres depends on the room dimensions, the height of the speaker from the floor, and the desired maximum sound field variation (usually 4 dB).
These speakers are suitable for sports halls, gyms, sales areas, trade fairs, museums, etc.
Distribution recommendations
Under conditions such as those mentioned above, for an 80 x 60 m enclosure, the installation recommendation would be:
- On 5 m high ceilings, 1 sphere every 200 m2
- On 8 m high ceilings, 1 sphere every 500 m2
- On 11 m high ceilings, 1 sphere every 1,200 m2
Acoustic coverage of standard ceiling speakers, with a coverage angle that narrows as the frequency increases.
Acoustic coverage of a sphere, wider (360º H x 180º V) and uniform for all frequencies.
Example
Sound reinforcement for a 65 x 80 m (5,200 m2) exhibition hall, with an ambient noise level of 75 dB SPL and a mounting height of 11 m.
SOLUTION
- For 11 m high ceilings, one loudspeaker every 1,200 m2: 5200 / 1200 = 4.33 (4 spheres)
- The attenuation loss will be 20·log(11 - 1.5) = 19.55 dB SPL
- The maximum desired variation in the sound field is 4 dB, which already includes the loss due to the distance from the listener to the axis of the speaker. speaker.
- Required SPL 1 W, 1 m (SNR = 15 dB): 75 + 4 + 19.55 + 15 = 113.55 dB SPL
- Therefore, a speaker with a maximum SPL > 113.55 dB SPL can be used.
