Loud and clear

The cochlea remains one of the relatively uncharted areas of the human body. Researcher Dr Paul Teal is helping to unravel its mysteries.


The spiral chamber, located inside the ear, turns sound vibrations into electrical signals that travel along nerves to the brain and allow us to hear.

“The cochlea is essentially a cavity in the bone,” says Paul. “You can’t pull it out and look at it, and it’s difficult to study in the body because of where it is located and the complex processes at work.

“Around the world, there is still a lot of dispute about how it even works.”

Paul, a Senior Lecturer in the School of Engineering and Computer Science, is researching better ways of measuring the cochlear microphonic, which is an electrical signal generated inside the cochlea. This could lead to techniques to more accurately assess hearing loss.

He has joined an international effort to build a finite element model of the cochlea which, if successful, will provide the first realistic, 3D picture of the physics of motion in a working cochlea.

The work is funded by the 7th Framework Programme for Research, a European Union initiative to fund research and development that develops high-quality knowledge. It comes under the Virtual Physiological Human (VPH) framework, which is developing open source digital data on the entire human body.

The ultimate goal for Paul, the only researcher from outside Europe to be part of the project, is to improve the diagnosis and treatment of hearing defects.

A healthy cochlea provides compression which amplifies quiet sounds more than loud sounds. In the most common form of hearing loss, this compression is degraded.

The current, standard test for hearing loss is an audiogram which, Paul says, effectively measures the softest sounds people can hear but is less reliable in gauging how well they hear louder sounds. He is experimenting with the use of advanced signal processing technologies to collect an electrical signal direct from the cochlea and more accurately assess hearing loss.

Paul is using gold-plated foam ear plugs that have electrodes clipped onto them to harness signals from deep inside the ear.

He hopes his work will result in the ability to customise hearing aids.

“Modern hearing aids are prescriptions based on population averages rather than an individual’s condition. My vision is that we will one day be able to connect people to a device that plays tones and sounds and gives an automatic read-out on the make-up of the hearing aid they need.”

Paul says the existing method of measuring the cochlear microphonic signal is invasive and, to diagnose problems, audiologists tend to opt for other, non-invasive tests that record the sounds the ear produces. However, these signals have limited use, partly because they are not always present, even in people with normal hearing.

“The reason we’ve gone back to looking for ways of collecting an electrical signal directly from the cochlea is the huge advance in electronics in recent decades.”

Paul is working with a surgeon from the Otago School of Medicine in Christchurch and a Canterbury audiologist to progress this strand of his work.

At the same time, he’s also focused on how to interpret the information gathered from the cochlea.

One of Paul’s breakthroughs has been to develop a model that combines understanding about both mechanical and electrical components in the way the cochlea behaves. The innovation has attracted considerable international interest.

It’s an exciting field of research, says Paul. “There is a lot yet to be learned and that has potential to deliver better treatments for hearing disorders.”