Observations: An app to tell you the songs you never knew you owned

WhoSampled will break down your musical prejudices and introduce you to artists that have long been nestling on your iPod though you had no idea they were there. The £1.99 iPhone app gives you the DNA of your tunes; picking out and identifying every snatched sample and every borrowed break.

The London-based tech start-up has compiled a data base of almost 150,000 tracks from more than 52,000 artists. It lists more than 82,000 samples, identifies 41,000 cover versions and 13,000 remixes.

Digging a little further into "Exhibit C", by rapper Jay Electronica (recently in the news over his relationship with a Rothschild heiress), I find that in one recording he has sampled Billy Stewart, Notorious B.I.G. and Gil Scott Heron, pictured below.

You can also follow the food chain in the opposite direction. Scott Heron's "The Revolution Will Not be Televised", which features on Jay Elec's track, also crops up on eight other tunes dating back to Schoolly D's "Treacherous" in 1988.

Sampling culture took hold around 1982 but its rise has been relentless. Nearly half of the US No 1s in the past three years have used samples. The most sampled artist of all time is James Brown, whose work crops up on no less than 1,979 tracks recorded by other artists and featured on the WhoSampled database.