Personalized Web radio service Pandora has added 15-second audio advertisements that will occasionally play between songs.
The company's official Twitter feed first announced the inclusion of ads, saying Pandora will be "extremely respectful of your listening experience" while promising "to be prudent."
So far, the ads have been used sparingly. Pandora's founder and chief strategy officer, Tim Westergren, told PressDemocrat.com in an interview that the average user will hear an ad only once every two hours, but the company is experimenting to see what works.
Pandora has experimented with audio advertising in the past. In early 2007, the service placed a 9-second McDonald's ad between songs the first time users changed stations. Each user heard the ad just once per day.
Asking for reaction, Pandora's chief technical officer, Tom Conrad, announced in a blog post on the company's site that users were generally upset with their decision to deploy audio ads.
"The reactions ran the gamut, from muted concern to strong condemnation," Conrad wrote. "Other listeners left comments on our blog, or contributed to posts discussing the ad on other blogs. The reactions in these other forums also expressed a variety of perspectives on the issue. Generally, though, there was fear that Pandora could become overwhelmed with intrusive audio advertising."
Subsequent to that experiment, Pandora removed all audio advertising from the site.
Now that audio ads are back, Pandora said in another Twitter update that those who wish to not hear any audio advertisements can sign up for Pandora's premium membership for $36 per year.