From Kanye and Jay-Z to Purcell, pitch correction software has transformed music. But is it innovation or merely cheating?
"My job used to be finding good singers. Now I just have to find good-looking singers."
This statement - made by a producer to Dr Andy Hildebrand, the inventor of Auto-Tune - will depress many.
Seventeen years on from its creation, opinions remain split on the software that can turn a duff note into a sweet one.
For some, it is the epitome of cheating. But for others, like performer Kanye West, pitch correction technology can be an instrument in itself.
Auto-Tune, the best known pitch correction software, was developed by Dr Hildebrand, an orchestral musician and oil industry engineer.
Having specialised in acoustic tests of seismic information, he realised in 1996 that similar technology could analyse and modify the pitch of audio files without excessively affecting vocal quality.
Dr Hildebrand, CEO and research scientist at Antares Audio Technology, was at a dinner party when a guest asked if he could work on a machine that could make her sing in tune.
"Everyone around the table looked glum," he said. "I worked on another project, then I looked back and thought, 'that's easy'."
In 1998 the public was introduced to the extreme end of the Auto-Tune effect - Cher's robotic vocal on Believe, which helped make it the biggest-selling UK single of that year.
Studio engineer Tom Bailey uses pitch correction more subtly and denies it has become a blanket tool for cheating.
The less you have to move a note, he explains, the more natural it sounds. "It's unfair to suggest that everybody has an enormous amount of pitch correction," he goes on.
"There have been some albums I've worked on where virtually none's been used, and there have been some where pretty much every note has been checked and adjusted."
For Radio 4 documentary Creating Pitch-Perfect, classical singer and Radio 3 broadcaster Catherine Bott visited composer and producer Steve Pycroft in his studio.
She submitted her own performance of Purcell's Music for a While for a dubstep makeover using one of several pitch correction programs.
Listening as her performance took on the clipped, robotic tones of a dance vocal, she said the result "exposes every nuance".
"What I'm hearing is this extraordinary technology revealing you to yourself.
"I deliberately didn't put much vibrato in the sound but pitch correction has added much more. It's Purcellian ornamentation."
For many music fans, however, feeding a vocal through a computer filter removes the vital ingredient - soul.
Music critic Neil McKenzie is one of them. "The singer is the human connection with the song," he says.
"It's the soul and the heart, and it's the thing you lose when you correct every possible defect.
"A lot of my favourite singers, like Bob Dylan and Leonard Cohen, don't have beautiful voices. They have character in their voice, and pitch correction is anti-character."
Lady Gaga, says McKenzie, can sing incredibly well on stage. But when he asked her why she used Auto-Tune, she effectively told him that kids expect to hear it.
"The sin of the tool is its lazy use has made it the ubiquitous sound of the modern vocal."
There are glimpses of innovation, however, not least Kanye West's 808s and Heartbreaks. The 2008 album, McKenzie says, created an atmospheric form of soulful "cyber blues".
Rapper Jay-Z, in contrast, released the 2009 track Death of Auto-Tune as "a line in the sand", warning against artists using the software as a crutch.
"I bear no ill toward Jay Z," says Dr Hildebrand. "For us as a company, the debate is a good thing. When he sang Death of Auto-Tune our sales went up."
Music critic Tom Ewing believes pitch correction software is just the latest in a long line of innovations.
"Cathedrals are also technologies of the human voice," he said. "The acoustics allow the voice to fill a space in a way that it can't do unaided.
"There's no reason why the human voice should be the only thing that doesn't get treated or manipulated."
Dr Hildebrand, meanwhile, does not feel responsible for the abuse of his product.
"I made the car," he says. "I don't drive it down the wrong side of the road."
Catherine Bott talks about her Purcell recording on In Tune on Radio 3 on Friday, 17 May at 16:30 BST. Creating Pitch-Perfect can be heard on Radio 4 on Monday, 20 May at 16:00 BST.