ART19 can provide insight into your audience size over a specific time range - this can be referred to as 'listeners', 'uniques' or 'unique listens'. We use unique IP addresses and user agents to determine one 'listener' within a specific time period - this IABv2.1 certified metric is available for both series and campaign statistics.
This data differs from downloads in that it relies on the given timeframe. For example, if the same person, on the same device and IP address, listens once a day for a month this will show as one daily unique but also one weekly unique and one monthly unique. If they listened once a month for a year then it would also show as one yearly unique, even if they have downloaded many times. Uniques can't be added together to get totals in the same way as downloads.
Unique listener reports are available at the network, series, episode, or campaign level. If you are interested in receiving a custom unique listeners report, please reach out to firstname.lastname@example.org.