auditory processing

Dr Tomlin working with Eliza in the clinic.

Hearing well is not all about having healthy ears or wearing hearing aids. As the saying goes, “We hear with our ears but we listen with our brains.” When the connection between ears and brain is damaged, it becomes difficult to hear sounds and conversations. You might be unable to understand speech at a noisy gathering or struggle to multi-task such as preparing a meal while listening to a conversation. In these cases, our in-built auditory processing system can fail to work properly.

What is Central Auditory Processing Disorder and do you have it?

“Auditory processing is different to hearing,” explains Dr Dani Tomlin, researcher and clinical audiologist at the University of Melbourne. “It’s how we interpret sounds and translate them into something meaningful. It’s how we localise sounds and amplify one over another,” says Dr Tomlin.

Here are the most common behavioural characteristics of CAPD.

Difficulty understanding speech:

  • when lots of people are talking
  • in busy, distracting and noisy places
  • in reverberant environments (eg. cafes with hard surfaces)
  • when rapidly presented
  • when sentences contain words with similar sounds
  • if you are multi-tasking while trying to listen

Auditory processing issues can happen with or without hearing loss but they often occur together, particularly in older adults. Researchers, including those at the HEARing CRC and The University of Melbourne, have identified practical ways to help people with CAPD improve listening capabilities. However, there are many things we still do not understand about this complex disorder.

What we do know is up to one in 10 Australian children are believed to be affected by Central Auditory Processing Disorder (CAPD). Many ageing adults acquire it as their auditory and central nervous system connections lose function and efficiency. Research also shows declines in working memory and attention as we age making it harder to hear and understand speech.

Children with recurrent ear infections or those exposed to nicotine (cigarettes) are also more likely to have auditory processing problems. But interestingly, both children and adults involved in musical activities appear to preserve speech listening skills better than others.

Dr Tomlin explains babies are usually born with the ability to hear but their auditory processing skills continue to develop into teenage years. So if ear infections block sound in childhood, the part of the brain involved in auditory processing seems to remain dormant or underdeveloped. “Children develop listening skills up until adolescence,” says Dr Tomlin. “Just as these skills develop in the early years, they are also declining as we get older. What’s not well understood is why, as we age, people find it harder to listen in noise. In particular, people with dementia do very poorly at listening in noise,” she says.

It is difficult to estimate how many older people are affected by CAPD because it can be hard to recognise. For example, its symptoms mimic other health issues such as hearing loss, attention deficit hyperactivity disorder (ADHD), autism, dementia, multiple sclerosis and brain injury. However, there are a range of tests (including auditory and cognitive tests) that can be done to identify it.

Increasing numbers of people seem to be affected by CAPD due to changes in our listening environment. “We have a harder world to listen in now. There are noisy classrooms and more adults are working in open plan offices and struggling to hear,” says Dr Tomlin. It means people have to make more effort to listen during conversation.

Unfortunately, increased listening effort leads to fatigue, meaning many people with CAPD can end up avoiding social interaction and become isolated and lonely. Research has shown that the less we use auditory pathways, the more we lose the ability to hear well. There may also be a link with this social isolation and higher chances of developing dementia. So how can this be prevented?

What can make you hear better? Other than hearing aids…

Technology has come a long way in providing hearing aids that assist people with CAPD. Many have in-built functionality to help the wearer understand what direction sound or speech is coming from and tune out distracting background noise. But there are many practical, simple things people can do to improve listening skills.

HEARing CRC PhD student Julie Beadle (pictured right), of the MARCS Institute, Western Sydney University, is hoping to develop a new listening test. It aims to improve current test methods by including visual and aural noise distractions to emulate real life conversations.

Her award-winning research reveals older adults find it harder than youngsters to understand speech in noisy situations but both groups are able to hear better if they see the speaker’s face. By removing visual distractions, such as people talking in the background and clearly presenting the speaker’s face, older people understand up to 50 per cent more than with visual and auditory noise.

“This is called the visual speech advantage,” explains Beadle. “Older adults can get just as much of a  visual speech advantage as younger adults. So it’s really important to look at a person’s face when they are talking. It’s where you get the extra information you need to process speech,” she says.

6 simple steps to better listening skills

  1. If you suspect you have a hearing difficulty, visit an accredited audiologist to have hearing and/or auditory processing tests. If you need hearing aids, use them (up to 80 per cent of people who would benefit from them do not use them).
  2. Make sure you face the person talking and focus on their mouth so you can pick up speech patterns, pitch, rhythms and visual cues.
  3. Try not to avoid social situations and keep the brain as active as possible. Consult an audiologist about training and strategies to improve listening skills.
  4. Pick social venues with acoustic-friendly furnishings that absorb loud voices and clattering. Choose a quiet table away from noise (piano/heaters/kitchens/passing foot traffic) and visual distractions.
  5. Ensure the area is well-lit so you can clearly see a speaker’s face. At work, consider using a microphone or sound-field amplification system.
  6. If you struggle to hear on the telephone, consider video technology such as Skype or FaceTime so you can observe facial cues as you listen.