Average sound exposure over a 24-hour period is often presented as a day-night average sound level (Ldn). Ldn values are calculated from hourly Leq values, with the Leq values for the nighttime period (10:00 p.m.7:00 a.m.) increased by 10 dB to reflect the greater disturbance potential from nighttime noises.

Day and Night Average Sound Level

Day-Night Average Sound Level - A-weighted equivalent continuous sound exposure level for a 24-hour period with a 10 dB adjustment added to the sound levels occurring during nighttime hours (10 p.m. to 7 a.m.)

LDN (text speak for London) is a single by Lily Allen which was released in the UK on 25 September 2006. It was co-written by Future Cut, and features a sample of "Reggae Merengue", written by Arthur "Duke" Reid. The song was originally released on strictly limited edition 7" vinyl (500 copies) in the UK on 24 April 2006, accompanied by album track, "Knock 'Em Out," and was re-released in September following the huge success of Allen's second single "Smile".

Low Dose Naltrexone

Median dose lethal to % of a test population

Leadership Development Network

U.S. term. See Listed Directory Number.

Local Directory Number

Listed directory number. This is generally an organization's central telephone number which appears in the telephone book.