Dec 9, 2010 09:01 GMT  ·  By

iTunes now offers the extended 90-second preview for certain songs. The company behind the service revealed plans to lengthen previews of purchasable songs last month, when the Cupertino giant sent letters to label representatives, notifying them of the change.

Researchers at Robert Morris University cited by CNet in November said that song samples played an important role in the buying process.

In a report released by the university in 2009, professor Min Lu and assistant professor Yanbin Tu reported that consumers were more likely to buy songs if they were allowed to sample the music for about 60 seconds.

Early last month, Apple said that the 90-second change would occur for songs that were at least two and a half minutes in length.

Apple confirmed plans to continue to offer the 30-second sample for songs that were shorter than two and a half minutes.

The Cnet report added that the Mac maker had already notified the top music labels and other business partners in the music industry about the change. Apple’s November letter is reproduced below.

Dear Label Representative:

We are pleased to let you know that we are preparing to increase the length of music previews from 30 seconds to 90 seconds on the iTunes Store in the United States. We believe that giving potential customers more time to listen to your music will lead to more purchases.

All you have to do is continue making your content available on the iTunes Store, which will confirm your acceptance to the following terms.

You agree that this letter modifies our U.S. Digital Music Download Sales Agreement so that “Clips” for songs longer than 2 minutes and 30 seconds may be up to 90 seconds long (“Clips” for shorter songs will stay at 30 seconds); and you agree to license, or pass through to Apple, gratis mechanical rights for 90-second “Clips” embodying the entirety of compositions owned or controlled, in whole or in part, by you or your affiliates. Further, you represent that you have the authority to enter into this letter agreement for 90-second “Clips”.

Thank you, The iTunes Store Team