The spacing of ceiling speakers can be divided according to constant voltage (70V/100V) and constant resistance (8Ω). The application of the two needs to take into account the differences in actual usage scenarios: broadcast systems, conference systems and home background music systems are very different in this regard.
Ceiling speakers layout generally has the above three types according to their radiating surface distribution. Taking the conference system as an example, the second layout is recommended, which is the minimum overlap method. The circle shown in the picture above is a sound field distribution diagram measured at the height of the listener's ear. The corresponding number of ceiling speakers installed is also related to the height of the room's ceiling and the effective radiation angle (direction angle) of the speaker.
The most common distribution rule is: the distance between two speakers should be greater than 2.5 times of the distance from a single speaker to a person's ear when standing. The distance for a broadcast system can be farther. For conferences, the sound pressure must be closer.
A more accurate algorithm is shown in the figure below. If you want to calculate the radiation radius, you only need to know the radiation angle and radiation height. Therefore, the distance between the speakers is approximately equal to the projected diameter of the speaker's radiation angle on an imaginary plane at the height of the human ear.
The following is our calculation based on the radiation angle of 60° and the radiation angle of 90°, as well as different heights, to estimate the number of speakers required for a 100㎡ room.
|
Radiation Height Radiation Angle |
2.5m | 3.0m | 3.5m | 4.0m | 4.5m | 5.0m |
| 90° | 9 | 6 | 5 | 4 | 3 | 3 |
| 60° | 25 | 17 | 13 | 10 | 8 | 7 |
In addition, in practical applications, the constant voltage (70V/100V) ceiling speakers of the broadcast system can be evenly arranged at intervals of 5 to 8 meters in venues no higher than 3 meters. If only background music is considered without emergency broadcasting, the spacing can be increased to 8~12m.
From the picture above, we can find that if we use speakers with large radiation angles, we can save the number of installations, the analysis from this perspective is correct. However, the directivity of loudspeakers with large radiation angles is poor and the corresponding critical distance is small, so it is very detrimental to improving speech intelligibility, so choosing an appropriate radiation angle is the key. Generally, a pointing angle of 60 degrees or 90 degrees is selected.
The layout of ceiling speakers on the ceiling should follow the principle of "symmetrical placement". Symmetrical distribution is conducive to the uniformity of the sound field.
