Apple has finally completed its purchase of song spotting app Shazam. The U.K. based app lets users identify songs by pointing a smart phone at the audio source. Apple did not give a price for the acquisition, but earlier reports say the iPhone maker paid around $400 million, far short of the most recent $1 billion valuation for privately held Shazam. In 1999, a Stanford Ph.D. named Avery Wang co-founded, with Dhiraj Mukherjee, Chris Barton, Philip Inghelbrecht, a tech start-up called Shazem, to offer a high-tech solution to listeners' longtime agony over not recognizing music on the radio or in bars, letting users identify songs through their phones' microphones. Shazam, which is based in London, said last year that it had reached one billion downloads on smartphones.