Research project: The Hearing Brain

The electrical activity of the brain when you hear a sound can be used to diagnose problems and to show benefit from hearing aids and cochlear implants. In particular it is widely used to test the hearing of infants.

A problem is that the activity is very small, typically a millionth of a volt, embedded in high levels of noise, so it is difficult to measure reliability. This research aims to improve measurement of this activity and to assess and improve its diagnostic utility. By doing this we also hope to improve understanding of how sound is processed in the brain. We ultimately want to improve clinical applications of such signals.

This project utilises a number of technical methods to improve the measurement of the tiny signals known as Auditory Evoked Potentials. This includes statistical methods, such as the ‘bootstrap’ approach, to improve the statistical detection of responses and new stimulation approaches, such as high rate maximum length sequences and chirps, to better evoke responses. We are also exploring how putting lots of electrodes on the head can improve measurement of activity and how the brain responds to natural stimuli such as speech.

Currently a doctoral in clinical practice student is investigating the reliability and diagnostic utility of cortical evoked potentials in young infants. Cortical responses have potential to assess speech perception and to evaluate hearing aid fittings in infants with hearing impairment.

Another project is exploring how such responses in the brain change over time following cochlear implantation.

Students associated: Pegah Hosseini, Siavash Mirhimadizoghi, Katie Ireland

Outcomes of the project so far:

• Demonstrating that measurement time can be greatly reduced using new stimulation methods (MLS and chirps).
• Finding an approach to combine the information from lots of channels to improve measurement quality.
• Understanding which statistical approaches for detecting responses work most effectively.