Image caption Could your teenager's iPod be a so-called "gateway drug"?

Calls to protect children from the dangers of the internet aren't new. But parents in one Oklahoma town are adding an unusual fear to the list: getting high from digital music.

Three students at Mustang High School just outside Oklahoma City were hauled into the principal's office recently after appearing to be intoxicated at school.

The students confessed that they had been "i-dosing" - that is, they claimed to be high after listening through headphones to sounds they had downloaded from the internet.

Local authorities were so concerned by this behaviour that they sent a letter to parents cautioning them about this bizarre new practice.

The whole incident raises the question: is it physically possible to get high from a noise?

'Messing with perception'

Dr Brian Fligor, director of diagnostic audiology at the Boston Children's Hospital, thinks the idea of digital drugs is as far-fetched as the plot of a horror film.

"To my knowledge there is no science that backs it up," Dr Fligor told the BBC. "They are experiencing an auditory perception."

The sounds available at i-dosing websites are called binaural beats. When listened to on headphones, they present one sound to one ear and a subtly different sound to the other ear.

I found it to be a somewhat amusing story Dr Brian Fligor, Director of diagnostic audiology at the Boston Children's Hospital

But when heard together, the human brain hears something different from the original sounds.

"It's just kind of messing with your perception of the sound," Dr Fligor says.

"It's neat and interesting, but it has absolutely no effect on your perception of pleasure or anything else that was claimed."

The teens, he says, may have been faking or may have been experiencing a placebo effect, unconsciously convincing themselves that they were indeed high.

But doctors would find no real physical effects of this supposed intoxication, he says.

I-dosing, Dr Fligor says, is "neither good nor bad. It's completely neutral. It's not the least bit harmful and so I found it to be a somewhat amusing story."

'Gateway' drug?

Still, parents are concerned that this seemingly benign activity may lead their children down a more dangerous path.

"The bigger concern is if you have a kid wanting to explore this, you probably have a kid that may end up smoking marijuana or looking for bigger things," Oklahoma Bureau of Narcotics and Dangerous Drugs Control spokesman Mark Woodward told The Oklahoman newspaper.

But while binaural beats could hardly be considered a "gateway" drug - that is, one encouraging experimentation with harder substances - the websites that sell i-doses appear to encourage sex and drugs.

The sounds - which retail for about $19.95 (£13) for four "doses" - are given names like "alcohol", "opium", "marijuana", "peyote" and "orgasm".

One site directs users to an online retailer of legal hybrid plants that it is claimed induce marijuana-like highs.

Suddenly, those concerns over rock and roll being the devil's music have started to feel pleasantly nostalgic.