Table 1.
We use the following indicators to characterize the sound environment.
| Measure | Description |
|---|---|
| L10 | Sound level exceeded 10% of the time—indicator of emergence |
| L90 | Sound level exceeded 90% of the time, measures level of “background noise” |
| Lday (Ld) | A-weighted equivalent continuous sound level over the period 7 a.m.–7 p.m. |
| Levening (Le) | A-weighted equivalent continuous sound level over the period 7 p.m.–11 p.m. |
| Lnight (Ln) | A-weighted equivalent continuous sound level over the period 11 p.m.–7 a.m. |
| Lden | A-weighted equivalent continuous cumulative exposure calculated from Ld, Le, and Ln. Corrections are applied by arithmetic addition to the levels measured in the evening (+5 dBA) and at night (+10 dBA). The levels of the three periods are then summed logarithmically |
| LAeq,T | A-weighted equivalent continuous sound level over time period T |
| LCeq,T | C-weighted equivalent continuous sound level over time period T |
| % days exceeding Lden = 65 | Standard calculation for comparing cities |
| % days exceeding Ln = 55 | Standard calculation for comparing cities |