Pupils perform 'alarming' feat

Pupils perform 'alarming' feat | Metro.co.uk

They can receive calls and texts during lessons without teachers having the faintest idea what is going on.

The Mosquito technology is said to play on a medical phenomenon called presbycusis, or age-related hearing loss.

It is thought to begin at 20 and first affect the highest frequencies – 18 to 20kHz.

The device was developed by Merthyr Tydfil-based Compound Security.

Boss Howard Stapleton said: 'I think it is a giggle. A teacher would be able to hear the sound only from 1m away. Teenagers could hear it from much further away.'