Imagine you’re listening to Simon & Garfunkel’s “Mrs. Robinson” on Pandora Radio. The only candidates you’re thinking about are the ones referenced in the song. Until the commercial break.

Suddenly, there’s a candidate, asking for your vote in the upcoming election.

Although entertainment platforms such as Pandora Radio are nonpolitical in nature, it is becoming more common for most of their 125 million users to hear campaign advertisements between songs.

Much like Pandora matches listeners with their preferred music through the Music Genome Project database — which analyzes and suggests songs based on factors such as melody, harmony and instruments — Pandora attempts to match listeners with relevant advertising. 

When users register with the music and comedy streaming service, they enter in their date of birth, ZIP code and gender, giving Pandora the ability to target ads to the users who would find them relevant.

“You can target your advertising on a listener by listener basis,” Pandora founder Tim Westergren said.

Unlike traditional radio, advertising takes up a small percentage of the airtime on Pandora. Audio ads that take a maximum of 30 seconds are played once every 20 minutes on the service. Accompanying the audio ads are on-screen banners that  direct the user to more information, typically the campaign’s website.

Campaigns that advertise on Pandora are able to see how often the advertisements cause users to act, whether that is visiting a campaign site, signing a pledge, sending an email or some other form of interaction.

“Based on different response rates, [advertisers] can tell which messages are resonating with which users,” Westergren said, explaining that this feature, coupled with the ability to target, makes advertising on a platform such as Pandora the “holy grail of political advertising.”

So far, a number of political campaigns have placed advertising on Pandora, including Barack Obama’s presidential campaign in 2008, Texas Gov. Rick Perry’s presidential campaign earlier this year and the Democratic National Committee, according to Westergren.

Looking forward, Westergren said, these kinds of online advertising platforms will be an important factor in the 2012 elections. “The candidates who use it effectively are going to have a huge advantage,” he said.

Another entertainment-streaming service that hosts campaign ads is Hulu, the website that allows users to view television shows, clips and movies on their computers.

As with Pandora and other forms of Web-based advertising, Hulu allows advertisers to target to users based on multiple demographic factors, including location. Hulu also lets users choose which ads are most relevant to them, the theory being that advertisers can reach a more engaged audience.

Jeff Jacobs, president of campaign consulting firm NextGen Persuasion, sings the praises of such narrow-band ads. “You can target really well,” he said, “even better than you can with TV.”

NextGen Persuasion consulted with Democratic incumbent Tom Perriello’s unsuccessful re-election campaign in Virginia’s 5th Congressional district in 2010, which ran ads on Hulu.

“This is where people are now,” Jacobs said about online advertising on platforms such as Hulu. “If you want to survive as a campaign and get your message to voters, you need to be in those places.”

Jacobs explained that these new forms of advertising should be added to, not used to replace, traditional forms of campaign outreach. 

“You may get them when they’re watching TV as well, but wherever their eyeballs are, that’s where you want to be,” he said, explaining that radio, television and now online ads have never replaced things like town hall meetings or knocking on doors.

Users can expect to see campaign ads on video games as well.

In 2008, Obama’s campaign ran in-game advertisements on Microsoft’s video game console Xbox 360. According to a release on Microsoft’s website, the campaign ads ran in the game “Burnout Paradise,” where users would drive their virtual cars past billboards featuring Obama’s picture and urging users to visit the campaign website, VoteForChange.com.

According to Julie Germany, vice president of public affairs firm DCI Group, these are the kinds of platforms that politicians should be paying attention to, even though they tend to be nonpolitical in nature. 

“As our entertainment and media-consumption habits change, political campaigns will need to adjust their communications, persuasion and outreach tactics,” she said in an email. “Where blogger outreach, online and mobile advertising and social media are all being used to reach voters today, other tools, including interactive outreach on entertainment systems like the Xbox, will reach voters tomorrow.”