Time spent listening (TSL) is one of the measurements surveyed by Arbitron in determining ratings for radio stations in the U.S.. The TSL is the amount of time the average listener surveyed spent listening to each radio station at one time, before changing the station or turning it off.
The TSL is an estimate of how long the average panelist (listener) was exposed to a particular station or stations for a specific time period.
It is the equivalent of Average Time Exposed (ATE), Daily or Weekly.
TSL trends are helpful in determining if programming decisions are having an effect on the audience.