• by Steve McClellan  @mp_mcclellan, November 3, 2011

Music company Pandora says it commands about a 4% share of all the music that is heard by radio listeners in the U.S. But its ad sales lag way behind, given what company officials call a lack of adequate measurement techniques by Nielsen and Arbitron and others in the media measurement space. "That's a key issue for us as we move ahead and try to grow at a faster pace," said Pandora CEO Tim Westergren in comments to reporters after a town hall-style address to employees at Horizon Media's New York headquarters on Thursday.

The company, which claims 100 million registered users, combines internal and external measurement sources to come up with the 4% figure.

But the lack of an accredited third party cross-platform measurement system has been “a bit of an inhibitor,” in terms of ad sales, acknowledged John Trimble, chief revenue officer at Pandora.

Asked how the company pitches to clients, Trimble quipped, "a combination of brand and brawn." What the company actually does, he added, is approximate average quarterly-hour ratings by combining unique visit and time-spent data.

In guidance offered earlier this year to investors, the company said it expects to generate revenues of roughly $275 million this year. Most of that money will come from ad sales, while small portions will come from both subscriptions and commissions from music sales attributed to the Pandora platform.

The company is working Nielsen, Arbitron and others to devise a cross-platform system to accurately measure its listenership, said Trimble.

But it's a daunting task -- as Pandora users increasingly shift from listening online at their PCs to listening via an array of over 400 devices, most of which are mobile, including smartphones, tablets and sets that are integrated into a number of automobile models. The company even has integration agreements with Samsung and LG to embed Pandora’s platform into several not-so-mobile refrigerator models for kitchen-bound listeners.

Westergren stressed that Pandora sees itself as a competitor to everybody in the radio space, including terrestrial broadcasters, satellite operators and music streaming companies. "We need a common currency," he said.