Aggregate Tuning Hours

This is the total number of hours of listening that your USA based webcast listeners collectively put in over the days covered in your report. The official definition is given in §370.3(b)(1) of the Copyright Office rules and regulations

Obtaining ATH numbers

Aggregate Tuning Hours ATH is the official unit of audience size. ATH is the total number of listener-hours aggregated over some period of time. ATH equals the length of the period of time in hours multiplied by the average number of listeners during the period of time. For an NW, two periods of time are involved:

Minimum-fee NWs do not report monthly ATH. Instead, they certify, on the monthly SoA, that it was within the minimum-fee limit. If you are confident your audience size is below the 218 threshold, and that your streaming server logs would prove it, then you don't even need to know your monthly ATH.

A report of use includes the ATH for the report period and you need to obtain a number for this purpose.

One way is to derive ATH from stream log files. If you outsource streaming to a service provider, they should be able to give you the ATH numbers you need. If you or your campus IT service runs your stream server then you can do it yourself. Crunching log files into ATH is impractical by hand but easy for a computer and for Spinitron.

Alternatively, you might choose to estimate the reporting period ATH. If you have an idea of the average number of listeners to your stream, you can simply multiply that by the number of webcasting hours in the reporting period. For example, if, on average, there are 20 listener connections to a webcast (with 24-hour programming) and the report period is 2 weeks then the ATH estimate is 20 × 14 × 24 = 6720.


Every US-based webcast must comply with SX rules and needs ATH information. A service provider that can't provide it is not up to snuff. Remind the service provider that ATH is accumulated only from connections originating in the USA and only while the stream is not transmitting dead air.