London, Sep 26 (IANS) Researchers in New Zealand have restored the "true sound" in the earliest known recording of computer-generated music that British mathematician Alan Turing's pioneering work in the late 1940s helped create.

Jack Copeland, Professor in Arts at the University of Canterbury, along with Jason Long, a New Zealand-based composer and performer, said their work made it possible to restore the recording -- with the result that the true sound of the ancestral computer can be heard once again, for the first time in more than half a century.

In 1951, a BBC outside broadcast unit in Manchester used a portable acetate disc cutter to capture three melodies played by a primeval computer. This gigantic computer filled much of the ground floor of Alan Turing's Computing Machine Laboratory.

Today, all that remains of the recording session is a 12-inch single-sided acetate disc, cut by the BBC's technician while the computer played.

The computer itself was scrapped long ago, so the archived recording was the only window on that historic soundscape that the researchers had.

The researchers discovered that the pitches were not accurate -- the recording gave at best only a rough impression of how the computer sounded, Copeland and Long said in a blog post on the British Library website.

But with some electronic detective work it proved possible to restore the recording, they added.

"Alan Turing's pioneering work, in the late 1940s, on transforming the computer into a musical instrument has largely been overlooked: it's an urban myth of the music world that the first computer-generated musical notes were heard in 1957, at Bell Labs in America," Copeland and Long wrote.

Computer-generated notes were emerging from a loudspeaker in Turing's computing lab as early as the autumn of 1948, they noted.

Alan Turing, who broke the WWII Enigma code, is widely acknowledged as the father of modern computer science.

As depicted in the 2014 Oscar-winning film "The Imitation Game", Turing was prosecuted in 1952 for homosexual acts, when such behaviour was still a criminal act in Britain. He underwent chemical castration as an alternative to prison.

Turing killed himself in 1954 at the age of 41. Queen Elizabeth II granted him a posthumous pardon in 2013.