Intelligent earplug could help avoid damage to hearing

A pilot scheme of the system — which encompases the special earplugs and database — is currently being carried among 80 workers at Norwegian company Statoil, overseen by researchers at SINTEF.

About 600 new or aggravated cases of hearing damage are reported to the Norwegian Petroleum Safety Authority each year.

‘Statoil has realised that this is one of the last things that are happening to their workers — they are losing their hearing — everything else is very safe offshore,’ said Olav Kvaløy of SINTEF, the Norwegian Research Institute.

The earplug itself is a variant of one already developed by SINTEF and produced by Nacre AS for the military, but now with electronics that are safe for a gas environment.

It is equipped with an external microphone that picks up noise from the surroundings. The sound is processed digitally and harmful noise filtered out. It is then transmitted to the loudspeaker on the inside of the plug so that the wearer can hear what is going on in his or her surroundings.

A microphone installed on the inside of the ear plug picks up speech signals through the wearer’s skull. This makes the mouth microphones commonly used in traditional hearing-protection devices superfluous.

Since speech is registered within the ear canal, the wearer avoids exposure to background noise, which is the case with traditional mouth microphones.

The innovation with the current system is the ability to perform threshold measurements, by constructing an audiogram (or hearing curve) that indicates if a hearing problem is developing.

‘We’ve developed two different measurements, one is exposure the other is threshold,’ Kvaløy said. ‘The exposure uses the inner microphone and threshold is a different set of signals that you respond to, like you would when you go to an audiologist, but it’s done automatically.’

Importantly, all the data is fed back wirelessly to an anonymous database that is analysed by the SINTEF researchers.

‘We’re on totally new ground, we could have really new knowledge here,’ Kvaløy said. ‘You can do threshold in the morning and the evening, and you will have the exposure in between — if [the worker] has a different threshold in the evening, meaning he has a slight hearing loss in the evening, we can ask what was he exposed to between.’