The Digital Music Weblog is reporting that our favorite streaming audio music-recommendation service, Pandora, has begun inserting audio ads into the music stream for some listeners. One TDMW reader heard an ad for the McDonald's Dollar Menu, and wasn't pleased. Grant Robertson had a chance to ask Pandora's CTO Tom Conrad a few questions about the new ads. Conrad said that currently the ads are in trials and are only heard by 10% of Pandora listeners, each of whom hear a maximum of one ad per day, and the trial is targeted by listener age. The ads they're trialling run just nine seconds and follow the "NPR-style" "This station brought to you by..." format, and they're not considering any other formats right now. Head over to TDMW to read the.