Strutt|Criteria|Ratings|Sound Level|LDN calculates the Day-Night noise level `L_(DN)` and inserts it into the active row.
`L_(DN)` is calculated as:
`L_(DN)=10log(10^(L_D/10)+10^((L_N+10)/10))`, where:
`L_D` is the day noise level
`L_N` is the night noise level