Add several sound sources with the logarithmic rule to get the combined level, since decibels cannot simply be summed.
分贝为对数单位,不可直接相加。
| Item | Formula / Note | Source / Standard |
|---|---|---|
| Energy summation | L = 10 lg(Σ10^(Li/10)) | GB/T 3222 |
| Two equal sources | +3 dB for doubled power | Beranek |
| Day/night limits | 55/45 dB Class-1 | GB 3096-2008 |