The work could also be used in the long-term to develop a radical new type of hearing aid that can be customized using the hearing dummy to meet the different needs of individual patients. If the procedures gain clinical acceptance, a device could reach the market within 4 years.
The research is being carried out by a team at the University of Essex with funding from the Engineering and Physical Sciences Research Council (EPSRC).
The aim has been to enable hearing aids to be carefully calibrated so that they address the particular underlying hearing condition affecting each individual patient; and to ensure that they tackle the most common problem affecting hearing-impaired people - sound interference, which leads to an inability to follow conversations in noisy environments.
People also differ in how much they are affected by noisy environments, which is why developing a tailor-made approach represents such a significant breakthrough.
"Today's hearing aids don't help to separate sounds - they just amplify them," says Professor Ray Meddis, of the University's Department of Psychology, who has led the work. "So they often make everything too noisy for the wearer, especially in social situations like parties, and some wearers still can't make out what people are saying to them. They find the whole experience so uncomfortable that they end up taking their hearing aids out! This discourages them from going to social occasions or busy environments and may result in them withdrawing from society."
The first key advance has been the development of unique computer models (or 'hearing dummies') that can use the information collected during the tests to simulate the precise details of an individual patient's hearing.
By altering individual mathematical algorithms within the computer models, the dummy's hearing capabilities can be adjusted until they perfectly match the hearing characteristics of the patient (e.g. where there is damage to different parts of the ear). This will then indicate the likely cause of the patient's hearing impairment.
"In the same way that a tailor's dummy is used to measure and fit a garment for a particular person, our software dummy is used to gauge a patient's hearing requirements so that their hearing aid can then be programmed to suit their needs right at the beginning of the process without the need to come back for further time consuming adjustments to their device".
The second key advance achieved by Professor Meddis and his team has been in the design of new hearing tests. Current clinical practice focuses on 'threshold testing' to identify how quiet a sound can be while remaining audible, and hearing aids are generally prescribed solely on the basis of these tests.
The new tests, which are quicker and easier to use, concentrate on higher sound levels more typical of everyday life.
"Our work has shown that, when it comes to hearing impairment, no two people are alike," says Professor Meddis. "That's why two people with apparently similar hearing thresholds often react very differently to their hearing aids."
The third advance involves the early stages of developing a new kind of hearing aid that simulates how a normal ear works. The aim of this new aid is to restore the particular aspects of hearing that are faulty and to do this as naturally as possible.
In collaboration with hearing aid manufacturer Phonak, Professor Meddis and his team have now designed a lab-scale version of such a device which is already being tested on patients. The next step is to work with a manufacturer to fine-tune the software and then miniaturize the technology so that the device can be reduced to conventional hearing aid scale.
"Traditionally, the fitting of hearing aids has focused on symptoms, not causes," Professor Meddis comments. "Our aim has been to break through the limitations of current hearing aids and current hearing assessment procedures, and so ultimately enable hearing impaired people to play a much fuller role in society."
The three and a half year 'Hearing Dummy' project has received EPSRC funding totaling nearly £358,000. This funding has formed the backbone for a wider collaborative effort involving hearing charities (Deafness Research UK, Action on Hearing Loss), Phonak, the (Colchester) Hearing Care Center, the Colchester Hospital University NHS Foundation Trust and the Department of Computer Science at the University of Sheffield.
Professor Ray Meddis is recognized as a world-leading authority on the development and use of computer models of peripheral hearing.
The new hearing tests are quicker and easier to use than laboratory-based procedures because they have been changed into a simple 'tone-counting task' suitable for use with a minimum of training. (The tones have different levels and by comparing the number presented with the number heard, it is possible to infer what is heard and what is missed). In addition the number of trials involved in the testing process have been greatly reduced. They still, however provide the required accuracy necessary to produce all the information needed to assess a patient's needs thoroughly.
EPSRC is the main UK government agency for funding research and training in engineering and the physical sciences, investing more than £850 million a year in a broad range of subjects - from mathematics to materials science, and from information technology to structural engineering. www.epsrc.ac.uk
The University of Essex, founded in 1964, is one of the UK's leading academic institutions and the most internationally diverse campus-based university in Britain. It was ranked 9th in the UK in The Times research league tables following the last national research quality assessment, and 16th in England for student satisfaction, according to the National Student Survey for 2010. More than a quarter of Essex's 10,000 students are postgraduates, and more than 3,500 are international students, drawn from more than 130 different countries. The University has three campuses in Essex, and partnerships with a number of other education institutions across the region. Essex has 17 academic departments, grouped into four faculties covering the social sciences, science and engineering, humanities, and law and management. www.essex.ac.uk