Nervous patients who cannot stand the sound of the dentist's drill could be offered relief by a new device.
Scientists at London universities have developed a gadget which cancels out the sound of the drill, leaving people free to enjoy their own music.
Patients simply unplug their headphones, plug the device into their MP3 player or mobile phone and then plug their headphones into the device.
People can still hear their dentists and other staff speaking to them -- the tool is designed to filter out only the sounds of the high pitch of the drill.
The gadget contains a microphone and a chip which analyses the incoming sound wave and then produces an inverted wave to cancel out the unwanted noise.
It also uses technology called adaptive filtering to "lock on" to sound waves and remove them, even if the amplitude and frequency change as the drill is being used.
Experts from King's College London, Brunel University and London South Bank University are hoping to attract funding from an investor to develop the device further.