For any system to be effective, the speakers must operate above the ambient (background noise) level of the respective area. Ideally this should be a minimum of 6dB, up to an ideal of 10dB higher than ambient sound levels in the location to be covered. Some typical example levels are shown below.
Typical background noise levels in dB(A)
| Ambient Noise dB(A) | |
|---|---|
| Lounge | 70 |
| Toilets | 60 |
| Entrance Lobby and Lounge | 73 |
| Conference Room | 70 |
| Speciality Restaurant | 65 |
| Cultural Centre | 70 |
| Bar Lounge | 65 |
| Meeting Room | 70 |
| Health Club - Aerobics | 75 |
| Health Club - Internal | 68 |
| General Office | 50 |
| Restaurant/Canteen | 65 |
| Call Centre Office | 67 |
| Mainline Station Platform | 75 |
| Football Match Crowd Noise | 95 |
At any listening position above, the optimum PA level needs to be 6-10 dB higher. On large system designs where performance is vital, it is important to factor in the loss in dB over distance to ensure the speaker produces enough output to compensate for the distance.
Eg. Factory with a ambient level of 72dB(A) Ideal PA level at the listener is say 80dB(A) Speakers need to mount 8m away from the listeners on structural steelwork. Loss over 8m is 18dB Therefore the level required at the speaker needs to be a minimum of (80+18) = 98dB(A).
Choose a speaker capable of producing this level by checking information on the manufacturers datasheets or speaking to your dealer.