Abstract: Audible media among different channels is recorded and analyzed to identify repeated instances of the same media item, either within a channel or from channel to channel, over a span of time. Such media items are identified as possible advertisements. A verification process is performed to determine which of these advertisement candidates are in fact advertisements. Once advertisements are so identified, audio from various sources is monitored to identify subsequent occurrences of that advertisement by matching the monitored audio against the stored signatures. In such a manner, advertisement flighting (broadcasts) as well as user exposure to advertisements can be detected and tracked.