The hearing on 2 December will examine whether the recently introduced electronic audience measurement system is having a negative impact on the business of radio broadcasters that serve black and Hispanic audiences – a number of whom have complained about seeing their ratings drop since the new system went online.

Committee chairman Ed Towns (pictured) says the “unprecedented decline in ratings” gives cause for an examination of “the possibility of methodological flaws in the implementation of the PPM”.

While Arbitron has previously acknowledged difficulties in recruiting ethnic minority panellists and ensuring they regularly carry their PPM device, it says it has since made “methodological enhancements” to address these and other issues.

The firm maintains that differences in listening figures produced by the PPM system and the paper diary method it replaces are due to the fact that PPM measures actual listening, while diaries only measure recall and loyalty.

Commenting on the upcoming hearing, Arbitron CEO Michael Skarzynski said: “Arbitron welcomes this opportunity to discuss the importance of electronic measurement, the effectiveness of the PPM, the value of the data it produces, and our responsible approach to the development of the service.”

PPM ratings have become the buy/sell currency in 25 of the biggest radio markets in the US, with a further eight due to make the switch from paper diaries before the end of the year.

The Oversight Committee began its probe of the PPM system in June, following the earlier launch of a Federal Communications Commission inquiry.

Chairman Towns and the committee subpoenaed documents from the Media Rating Council (MRC), the body responsible for auditing media measurement systems, which has so far only granted accreditation to the PPM system in two markets.

The Oversight Committee has claimed that analysis of the subpoenaed MRC documents show “persistent problems” with minority audience samples in the PPM system, however Arbitron has disputed that conclusion, calling it “erroneous”.