NeuroEngineering Research Lab
Audition, Speech and Bionic Ear Design
Audition (hearing) is the primary sense required for speech. It also plays a major role in language. Audition involves the transduction of sound waves from the ear drum in the outer ear to the cochlear in the inner ear. Within the cochlear vibrations associated with the sound waves are transformed into electrical signals which are relayed to the brain via neurons in the auditory nerve. The brain interprets these signals and uses them to perceive sound.
There are two common causes of hearing impairment.
- The first is a reduction in the ability to transduce vibrations from the outer to the inner ear. This requires a hearing aid to increase the amplitude of the sound waves entering the ear in order to compensate for the weak transduction of sound vibrations.
- The second is the inability of the inner ear to stimulate auditory nerve neurons and transmit sound information in the brain. When this is caused by the inability to transform the sound vibrations into electrical signals at the inner ear/auditory nerve interface one solution is the cochlear implant. This is a surgically implanted device that detects sound waves using a microphone, transforms these sound waves into electrical signals, and stimulates the auditory nerve so sound information can be transmitted to the brain.
Our research goal is to study, understand and improve technology for the hearing impaired.
Research projects include:
- cochlear implant design
- hearing-aid design
- neural modelling of the auditory system
- sound localization
- speech processing
- speech recognition.
Computational neural modelling of bottom-up information and top-down attention in auditory perception
Researchers: David Grayden
The primary aim of this project is to advance our understanding of how the brain processes auditory information and how it can make sense of acoustic signals that are often mixed with other sounds in frequency and time, depending on the current behavioural or perceptual needs. In particular, we aim to investigate the processing strategies used in the auditory cortex to enhance the perception of relevant sounds in the presence of background noise and distractors. We will develop neuronal network models that will be used to elucidate the mechanisms by which attention and plasticity modify neuronal responses in a task-dependent fashion. The models will be constrained by electrophysiological and behavioural data recorded some of the world’s top experimentalists. This understanding is likely to be relevant for other sensory modalities.
A better understanding of the impact of top-down processes on perception through a computational approach will be a significant step forward in neuroscience. The outcomes of this research will yield new insights into information processing in the brain, which is of interest to neuroscience research in general and to those working on brain-inspired computation. In addition, the procedures used will offer valuable results concerning the development, optimisation, simulation and analysis of large-scale spiking neural network models.
Neural activity shaping for retinal and cochlear implants
Researchers: Anthony Burkitt, Tatiana Kameneva
This project aims to develop methods to control and optimise the spatial patterns of neural activity evoked by neural prostheses in order to improve the resolution of neuroprostheses. A major problem for neural prostheses is that the electrical current used to stimulate neurons causes a diffuse spread of activity in the neural tissue, which limits the resolution of the device. For patients this
translates into limitations in sound quality, in the case of cochlea implants, or visual acuity, for retinal implants. The outcome of the project will be algorithms that optimally choose the currents on each electrode so as to shape neural activity at the finer resolution of electrode spacing rather than the coarser resolution of current spread.
Professor David Grayden
T: +61 3 8344 5234