British festival-goers this summer no longer need to worry about charging their phones - as long, that is, as they're not too bothered about their eardrums either.
Mobile carrier Orange is testing a 'Sound Charge' T-shirt at this week's Glastonbury festival that uses sound to power a mobile phone via piezoelectric film.
The company's put an A4 panel of the modified film inside a t-shirt - sorry, but you'll need to not care much about fashion, either - which then works much like a microphone to absorb sound pressure waves.
By compressing the interlaced quartz crystals, the sound waves are converted into an electrical charge, which feeds into an integral reservoir battery to charge most makes and models of mobile phone.
Bass frequencies work best. Orange claims that with sound levels of around 80dB - around the same as a busy street - the device will generate up to six watt hours of power over the course of the weekend. This should be enough, it says, to charge two standard mobile phones or one smartphone.
"In a vibrant festival environment such as Glastonbury, sound is such an obvious medium that it seemed like a natural fit to use it in the development of this year’s prototype," says Andrew Pearcey, head of sponsorship at Orange UK.
"We envisage that this pioneering technology could really change the face of mobile charging in environments where eco charging solutions need to be found."
Rather optimistically, he adds: "It could even influence trends in fashion."