How many Radio stations does the average listener
On average, Nielsen Audio's PPM shows that listeners are exposed to 6 Radio stations per week.
(Analysis of Nielsen Audio's PPM vs. Diary, 2009)
Cume Persons is the number of different persons who listened to a station for a minimum of 5 minutes within a reported daypart. (Cume estimates may also be referred to as Cumulative or Unduplicated estimates.)
Average Quarter-Hour (AQH) Persons is the number of persons listening to a particular station for at least 5 minutes during a 15-minute period. AQH listening by a single person is counted for each 15-minute period that listener is tuned in - hence there is duplication in reported AQH estimates.
(Definitions from Nielsen Audio's "A Guide to Understanding and Using Radio Audience Estimates")