Billboard magazine this Friday (Dec. 1) will unveil a new ringtone chart measuring weekly sales of the top 20 master ringtones in the U.S.

The new chart, called Hot RingMasters, replaces the former Hot Ringtones chart, which first debuted in late 2004. The old chart only tracked polyphonic ringtones, using data collected from various ringtone aggregators.

However polyphonic ringtones have fallen out of favor with mobile customers, who prefer master ringtones-which feature snippets of the actual song as opposed to a synthesized cover. According to an August report from mobile metrics firm Telephia, more than 76% of the ringtones sold today are master ringtones, while polyphonic account for only 12%.

The first No. 1 on Hot RingMasters belongs to Akon. His "Smack That," with Eminem, one of two singles that Akon has riding in the top five of The Billboard Hot 100 and Hot R&B/Hip-Hop Songs, leads all masters with 164,000 sold. That's 54,000 more than the units sold for this week's top selling download, Akon and Snoop Dogg's "I Wanna Love You."

The latter Akon track is No. 3 on Hot RingMasters, trailing the runner-up title, Beyonce's "Irreplaceable." Each of the top three masters surpass 100,000 units for the week that ended Nov. 26. And, the RingMasters chart leans heavily toward hip-hop, with "Lips of an Angel" by rock band Hinder at No. 6 being the sole entry in the top 10 that does not fit urban radio formats.

Data for the Hot RingMasters chart comes from the new Nielsen RingScan monitoring system, which measures all ringtone formats-polyphonic, master and voicetones. Sales figures are collected directly from a comprehensive sample that includes wireless operators participating in the RingScan program, as well as ringtone aggregators and other sources.

The Hot RingMasters chart will run in the print edition of Billboard magazine every other week, and every week online at The Hot RingTones chart will be accessible only online.