Adding another media dimension to its promising audience measurement system, Arbitron Monday announced plans to test the measurement of cinema ads as part of a new market trial of its portable people meter system in Houston beginning later this year. Regal CineMedia, the advertising unit of Regal Entertainment Group, said it would embed Arbitron's PPM codes in "The 2wenty," a short, ad-supported film that will run before the main features in two theaters in Houston during the trial. The PPM is capable of measuring exposure to TV and radio - both in and out-of-home - and potentially to any other medium capable of emitting and audio signal. The system also is a key component of the Apollo project, a joint venture of Arbitron and VNU to develop a single source system for measuring media exposure and product purchases. -- J.M.