Given the recent changes in the policy governing Internet content distribution, such as the institution of per listener royalties for Internet radio broadcasters, content distributors now have an incentive to under-report the size of their audience. Previous audience measurement schemes only protect against inflation of audience size. We present the first protocols for audience measurement that protect against both inflation and deflation attempts by content distributors. The protocols trade-off the amount of additional information the service providers must distribute to facilitate audience inference with the amount of infrastructure required and are applicable to Internet radio, web plagiarism, and software license enforcement. The protocols can be applied to other situations, such as auditing website screen scrapers and per-seat licensed software installations.