An earplug passes the word

By Anne-Lise Aakervik

An earplug with a built-in computer that conveys speech but blocks unwanted and harmful sounds, will make life easier in noisy environments.

Imagine the following scenario: Norway is up against Italy in the quarter-finals of the European Football Championships. The crowd is roaring, drumming, whistling and singing. The coach is desperately trying to get a message across to one of his players. If the players had been wearing a new type of earplug, they would have heard their coach giving very specific directions and - who knows - perhaps the outcome would have been different.

- This might be possible, but I'm not convinced it is permissible, says senior researcher Jarle Svean at SINTEF Telecom and Informatics. Svean has been a key figure in the development of the Personal Active Radio/Audio Terminal (PARAT).

Each PARAT earplug contains a miniature loudspeaker and an inner and outer microphone. The inner microphone measures the noise in the ear. Initially, the earplug blocks out all noise, but an electronic chip transmits selected sounds. In quiet conditions, the earplug "opens up" and the wearer hears everything normally. However, as soon as it registers significant noise, the PARAT shuts out the unwanted sounds, and transmits only normal speech. The electronic circuitry is built into a tiny chip embedded in the earplug. In combination with a radio, it offers a complete communication terminal for use in a noisy environment.

To demonstrate the potential of this sophisticated device, PARAT is currently being tested at SINTEF Telecom and Informatics in a laboratory with powerful loudspeakers generating lots of noise. The researchers fit a mobile phone with earplugs. The earplugs act as a speaker for the caller and a microphone for the phone user. Ordinarily, a phone conversation would be impossible in this din, but with the help of the earplug connections, the voice of the caller can be easily heard by the user and vice versa. The vibrations from the voice of the user are transmitted to the inner microphone in the earplugs through the tissues of the head.

- With the help of PARAT's inner microphone, it is possible to measure the level of noise actually reaching the eardrum. This allows us to determine an individual's exposure to noise and make arrangements to prevent injuries to the auditory system, Svean explains. PARAT can, for instance, be used at assembly lines or in the machine room of a ship for radio communication with the bridge. The Norwegian company NACRE AS is now developing production prototypes for PARAT.

* Contact at SINTEF: Jarle Svean
Tel: + 47 73 59 27 23
E-mail: Jarle.Svean@informatics.sintef.no