Triton Digital has released its monthly Internet audio Top 20 Ranker for September 2012, listing the top-performing Internet audio stations and networks. Topping the charts are Pandora, Clear Channel, Cumulus Streaming Network and Slacker. However the largest webcasters witnessed very little growth month-to-month, as Pandora's “Average Active Sessions” (defined as total listening hours divided by number of hours in the reported time period) was up 3%, while CBS's AAS continued to drop; 11% since August.
“Session Starts” is defined as the number of different requests for streams (i.e., stream requests) with a duration of at least one minute in total within the reported time period, while “Average Time Spent Listening” is defined as the average number of hours for each session with a duration of at least one minute in total within the reported time period – calculated as total time spent listening divided by active sessions.
Rankers are divided into “Domestic” and “All Streams.” The Domestic ranker quantifies listening done inside the U.S. based on log-based information provided by the station (not MRC accredited), and the All Streams ranker verifies the quantity of streams without qualifying where they are being consumed (and is MRC accredited).
Check out the chart below (click image to enlarge):