For the music business, Twitter holds a vast haystack of data with no easy way to find the most valuable needles — like which acts are attracting the most attention, and where.

To help find them, Twitter has turned to 300, a new company started by one of music’s biggest power brokers, Lyor Cohen. Mr. Cohen announced the partnership on Sunday at Midem, an annual music industry conference in Cannes, France.

“There was a time not so long ago when we sold music to retailers and they sold to fans, but nobody knew who those fans were,” said Mr. Cohen, 54, who started as a hip-hop promoter in the 1980s and rose to top posts at Island Def Jam and Warner Music Group. “I’ve spent most of my life not knowing who the customer is. Isn’t that a shame?”

The reading of music’s digital tea leaves has become a big business as companies like Gracenote, Next Big Sound and Musicmetric have joined traditional players like Nielsen in providing information about music online. But while music is the most popular topic on Twitter — users discussed it in more than one billion messages last year — its depths have not been fully plumbed.