Audiology and Deafness: Research projects
Physiological bases and perceptual consequences of 'hidden' noise-induced hearing loss
Noise exposure is the main cause of preventable hearing loss worldwide. Noise exposure occurs in the workplace, such as in noisy factories, and recreationally, through the use of personal music players and attendance at nightclubs and live music events.
Until recently, it had been assumed that hearing loss results mainly from damage to the sensory hair cells in the cochlea, the part of the ear that converts acoustic vibrations into electrical impulses in the auditory nerve. However, recent results from animal studies suggest that moderate noise exposure can cause substantial damage to the auditory nerve, even when the hair cells are unaffected. The results suggest that such damage is not detectable by standard diagnostic procedures and could therefore result in a large number of people suffering from a 'hidden' hearing loss.
Our research: Our programme is far-reaching, involving three internationally-renowned institutions across the UK and USA, and a wide range of scientific methodologies. Headed by researchers in the Audiology and Deafness research group at the University of Manchester, the five-year MRC funded project will estimate the prevalence of hidden loss in young adults, the impact of hidden loss on everyday tasks and provide an initial investigation of potential diagnostic tools for future detection of this hearing condition which could affect millions of people in the UK alone.
To find out more, see: Investigating ‘hidden’ noise-induced hearing loss
Understanding risks for age-related hearing loss: UK biobank
Hearing loss is a very common problem, with almost everyone experiencing some hearing loss as they grow older. There are currently 10 million adults with hearing loss in the UK, and this number will increase in coming years.
Our research: Using the UK Biobank resource with data from over 500,000 UK adults, our work will provide unique insight into the prevalence of and the risk factors for hearing disability. We will also examine how hearing loss, visual impairment and dual sensory impairment affect quality of life. With a wide range of data included and the very large sample size, the UK Biobank provides a unique resource for doing this important research. Our ultimate aim is to identify ways of preventing hearing loss and improving quality of life for older adults.
Find out more: See the biobank.
This work is being carried out by Piers Dawes and Kevin J Munro in collaboration with leading scientists in the UK and US: Professor David Moore at Cincinnati Children’s Hospital Medical Centre, Dr Heather Fortnum, Dr Abby McCormack and Mark Edmondson-Jones at the NIHR Nottingham Hearing Biomedical Research Unit; Professor Adrian Davis, Royal Free Hampstead NHS Trust, London; Professor Mark Lutman, University of Southampton and Dr Karen Cruickshanks, University of Wisconsin.
Early detection of hearing damage due to noise in the workplace
Noise exposure is the most common cause of preventable hearing loss worldwide. In the UK, over 2 million people are exposed to noise in the workplace. Recent evidence from animal research suggests that the most common test used to diagnose noise-induced hearing loss may be insensitive to early changes caused by noise damage.
Our research: We are working to determine whether similar damage occurs in humans who work in noisy environments. We hope that our work will lead to the development of a test that can detect noise damage earlier, allowing more severe damage to be prevented.
Find out more: see Detecting the early effects of occupational noise damage to hearing study
Fitting babies with hearing aids: progress means new challenges
Permanent hearing loss in infants is common and its impact on the child is vast. We now provide hearing instruments to infants at a few months of age but there is an urgent need for procedures that will guide the appropriateness of the prescription and when to expedite trials of alternative devices such as cochlear implants.
Our research: Previous studies have demonstrated that cortical auditory evoked potentials (CAEPs) can be successfully recorded in infants who wear hearing instruments. CAEPs have the real potential to tailor treatment to the individual and improve quality of life. Before embarking on a large scale trial, we are undertaking an essential underpinning study, on 100 normal hearing infants and 10 infants with hearing loss, to answer questions related to the natural changes that occur in the brain in response to sound as the infant grows, the ability to consistently detect a CAEP, as well as investigating the feasibility and acceptability of making these measurements in the clinical setting.
Find out more: see Cortical Auditory Evoked Potentials
This project is a collaboration between the University of Manchester and Central Manchester University Hospitals NHS Trust. It is funded by a CMFT strategic research grant The investigators include Rachel Booth, Iain Bruce, Martin O’Driscoll, Kevin J Munro, Ruth Nassar and Kai Uus.
Towards an objective audiology test battery
Most conventional hearing tests require patients to make a behavioural response to sounds that are played to them, such as pressing a button when they can detect a quiet sound. However, these procedures are impossible for young infants (who cannot understand spoken instructions), and difficult for some adults with special needs.
Our research: The aim of the project is to develop an objective audiological test battery, based on measures of the electrical responses of neurons in the brain to sound, that can automatically diagnose hearing disorders without the need for a behavioural response. In addition to the obvious benefits for infants and adults with special needs, the test battery could lead to faster and more accurate diagnoses for all patients with hearing loss.
Why so many annoying sounds?
The experience of ‘annoying sounds’ is a frequent complaint among new hearing instrument users, and failure to adjust to hearing aids may result in reduced benefit or non-use. Failure to tune out background sounds may also result in reduced performance in background noise. It may also be possible to optimize rehabilitation strategies based on individual differences in ‘attentional tuning’.
Our research: We are testing the idea that getting used to to hearing aids involves a process of learning to ‘tune out’ newly audible unwanted sounds (for example, buzzing strip lighting or a droning refrigerator motor).
Understanding and improving benefit from hearing aids: the Eriksholm “hearing aid use” study
Although hearing loss causes huge difficulties with communication, only one in six people who could benefit from a hearing aid actually use one. Of those who do use hearing aids, another one in six does not receive substantial benefit from their hearing aid.
Our research: We are part of a large multi-centre research project led by researchers at the Eriksholm Research Centre in Denmark. The aims of this study are i) to explore the definition and determinants of optimal hearing aid use from the perspectives of hearing aid users and audiologists and contrast the two, ii) investigate the determinants of hearing aid use and iii) develop and evaluate a tool for hearing aid use goal setting and assessment for audiologists and to use together with hearing aid users.This project is being carried out by Piers Dawes, in collaboration with Ariane Laplante-Levesque, Lisbeth Jensen, Claus Nielsen and colleagues at the Eriksholm Research Centre.
Transforming infant hearing services
Every week in the UK, another 20-25 children are born deaf and this can be confirmed soon after birth. The first days, months and years of a child’s life have a tremendous impact on development: theirs, society’s and the world’s. However, formal behavioural assessment of a child’s hearing cannot normally take place until they are able to turn their head in response to sound at around 8 months of age. There is an urgent clinical need to remove the unacceptable time delay between confirmation of deafness and obtaining reliable behavioural hearing assessment data.
Our research: We are about to embark on a study that will investigate a new hearing assessment technique for use with very young children. This involves tracking eye movements in response to sound in order to reveal whether this can provide reliable information about hearing. The aim is to provide confidence that the eye tracking technique is a viable approach to hearing assessment in individual infants. In this initial study, we will use the eye tracking technique with 100 infants with normal hearing.
This project is a collaboration between the University of Manchester and Central Manchester University Hospitals NHS Trust. This work is being carried out by Rachel Booth, Iain Bruce, Thea Cameron-Faulkner, Kevin J Munro, Martin O’Driscoll, Andrew Stewart and Kai Uus
Re-wiring the auditory brain
Contrary to the age-old myth, a leopard really can change its spots. The brain has an extraordinary ability to modify the way it works, to re-wire itself, following changes in the body or in the environment. It is most plastic during childhood, which is why babies can learn to walk and talk all on their own, and kids can soak new information up like sponges. But the brain remains surprisingly plastic even into adulthood. It is this lifelong ability to change and adapt which is associated with recovery after a stroke or sensory deprivation, or learning to use a prosthetic limb or hearing devices after deafness.
Our research: Our present work is involved in characterising the way in which the adult auditory brain re-wires itself following deafness. We take people who have gone deaf suddenly in one ear, and study the ways in which the brain learns to make best use of the hearing from their one good ear.
Understanding the effects of age on hearing
As people get older, they often struggle to hear, especially when many people are talking at the same time. One reason for this is that hearing loss becomes more common with age – it becomes harder to hear quiet sounds. However, even older people without hearing loss have hearing difficulties, possibly due to changes in the ear or brain that occur with age separately to the development of hearing loss. We are investigating the effects of both age and hearing loss on the auditory system. So far we have shown that both age and hearing loss affect the ability of the auditory system to synchronize to sounds, but in different ways. Ongoing work is investigating the effects of age and hearing loss on the ability to hear speech when several people are talking from different locations.
This project is being carried out by Andrew King, Kathryn Hopkins and Chris Plack in collaboration with Niels Pontoppidan and colleagues at Eriksholm research centre in Denmark. Andrew King is a PhD student in the School of Psychological Sciences.
The neural basis of musical consonance
When two or more musical notes are played together, the resulting chord can sound pleasant (consonant), or unpleasant (dissonant) depending on the frequency ratio(s) between the notes. We aim to determine the neural mechanisms that underlie this effect by using scalp placed electrodes to record the activity of neurons in the auditory system in response to consonant and dissonant chords. Our research has shown that consonance is represented by the temporal firing patterns of auditory neurons in the brainstem, which tend to synchronize strongly to the main periodicity of consonant chords. In ongoing work we are using this measure to determine how the representation of musical chords is affected by age and hearing loss.
Squashing sounds to make them audible
If you have difficulty detecting high-pitched sounds then this can prevent you from hearing some important speech sounds, even when you wear a hearing aid. A potential solution is to squash the high-pitched sounds down to a lower frequency to help make these speech sounds audible. In the present study, we are investigating the benefit of listening to speech with these hearing instruments when they are first fitted and after a period of adjustment/acclimatisation (with and without auditory training). The findings will have implications for the use of frequency compression and auditory training in auditory rehabilitation.
This project is being carried out by AnnMarie Dickinson, Richard Baker, Kevin J Munro and Catherine Siciliano in collaboration with colleagues at Phonak AG, Switzerland. The project is funded by Phonak AG as a three-year CASE industrial award (Plasticity, perceptual learning and real-world benefit with frequency-compression instruments: the role of auditory training). AnnMarie Dickinson is a PhD student in the School of Psychological Sciences.
To gain is to lose
Even when sound is not present, spontaneous neural activity can still be recorded from the auditory pathway. However, an increase in central gain, a mechanism that modulates the neural sensitivity within the auditory system can result in this spontaneous activity become hyperactive. This could potentially explain tinnitus, the perception of a noise/ringing in the ears or head without an external reference, in some patients.
We aim to characterise the gain mechanism, investigating the origin, time scale of changes and if it is frequency specific, following different periods of earplug deprivation. If we can understand more about this mechanism, it may become possible to deliver therapeutic strategies aimed at reducing the central gain, and potentially inform treatment decisions for symptoms such as tinnitus.
Listening effort in young adults and children
Have you ever wondered how difficult it is for hearing-impaired individuals to understand speech in noise? Noisy environments are ubiquitous e.g. cafeteria, classroom, bus etc. With even a mild hearing loss, the ability to detect speech in these settings is seriously hindered. As a result, people with a hearing loss often report an exhausting need for sustained mental effort to listen in these environments.
Using a wide range of psychophysiological techniques we aim to uncover a sensitive and reliable measure of this listening effort in young adults and children. If successful, such a measure could be used clinically when assessing hearing disability and assessing the benefit of interventions. We are hoping to undertake a similar research study in older adults too.This work is being carried out by Piers Dawes, Ronan McGarrigle, Kevin J Munro and Andrew Stewart. Ronan McGarrigle is a PhD student within the School of Psychological Sciences.
Eyes, ears and accents
Have you ever wondered how you “tune in” to someone’s accent? Humans have the remarkable ability to understand different speakers and accents, but it is not fully understood how this rapid perceptual adaptation takes place. We are carrying out research to understand how we adapt to hearing unfamiliar foreign or regional accents, and whether visual speech information (seeing a speaker as well as hearing them) helps people to adapt. We use eye-tracking (a way of measuring people’s eye movements) to investigate how older and younger adults combine visual and auditory speech information when adapting to a new accent. We also carry out neuropsychological tests to examine the role of cognition (such as memory, attention and linguistic processes) in understanding accented speech. The findings will help us to understand why some older people have difficulty understanding speech in difficult listening conditions, and may identify ways to help overcome this.
This work is being carried out by Briony Banks, Patti Adank, Emma Gowen and Kevin J Munro. Briony Banks is a PhD student funded by BBSRC (Audio-visual plasticity in spoken language comprehension in aging).
Hearing loss and broken pianos
We set out to find out how common cochlear dead regions are and how best to programme hearing devices when a person is identified with one. These dead regions are often compared to a piano with broken stings: pressing hard on the broken keys may cause adjacent strings to vibrate. A dead region occurs when inner hair cells and/or neurons are functioning so poorly that a tone producing peak vibration in this region is detected by off-frequency listening. A cochlear dead region may impact on patient counselling, selection of gain-frequency response, and hearing aid benefit.
We have conducted a number of research projects on the topic of cochlear dead regions in adults and in children. The findings will help inform audiologists about the need to diagnose dead regions, how to programme the hearing instruments and how to counsel people with dead regions. It will ensure that patients who need hearing instruments receive the best treatment possible and reduce unnecessary appointments for reassessments.
This work is being carried out by Karolina Kluk, Kath Lewis, Kevin J Munro and Anna Pepler. The project is funded by a grant from the National Institute of Heath Research. Anna Pepler is a PhD student in the School of Psychological Sciences.