Our ability to localise sound in the environment is crucial to our survival. Consider that sound can be heard 360° around our head, in the dark, and also through barriers; you can begin to appreciate that it is more important than vision or any other sensory system. Of course, in years gone by, we would need to be aware if a dangerous animal was chasing us from behind or at night – survival of the fittest auditory system!
In the modern-day world, localising sound is just as important. We need to be able to tell where a car is coming from or to be able to concentrate on the teacher’s voice as they move around the classroom.
The processing of sound is intimately linked into our stress responses. For many children and adults with sound localisation problems, their system is on alert as their auditory processing is compromised. Many children with Autism, Dyslexia, Dyspraxia, and other developmental labels have difficulty processing the direction of sound. This leads to a higher level of stress in the system. Listening, concentration and attention problems are common as well as disrupted learning and emotional and behavioural challenges. Increased stress levels become ‘stuck’ in the system leading to problems in social skills as well as learning.
Many people with problems with sound localisation develop a stronger visual system to compensate as much as possible. However, this still leaves the auditory processing problems.
We have no ‘earlids’!
It is easy to understand that if we want to locate something visually, we can move our head and eyes to look at it. However, locating sound in the environment is not as straightforward.
We do not have the benefit of many mammals in that we cannot move our ears to help locate sound. Horses, as with many other animals, can move their ears in multiple directions without moving their head to help with sound localisation. Humans cannot!
We cannot shut down our auditory system as we do not have earlids. The auditory system is active 24 hours a day, listening out for danger in our environment, even as we sleep. You can understand how auditory processing is so intimately linked with stress levels and how poor sound localisation can lead to increased stress.
For us, the outer ear or pinna is involved in locating whether sound is above or below us, but we rely on several other cues to be able to locate sound. The main ones are timing and volume differences between the two ears. These are called the Interaural Time Difference (ITD) and Interaural Level Difference (ILD)
Imagine someone speaking to you if they are standing level with your right ear. Their voice hits your right ear around 5 milliseconds earlier than your left ear. It also reaches your left ear at a slightly lower volume as your head has a shadowing effect which reduces the volume. Our ears also use the pitch or frequency of the sound to help to understand where it is coming from. I am sure you will agree that it is a miraculous system and with such complexity, it is not surprising that many people have problems with things such as sound localisation.
Do you or your child: -
Find it difficult to concentrate?
Have difficulty listening in the classroom or workplace but are able to listen in a 1:1 situation in a quiet room?
Become engrossed in the TV or video game and do not hear when someone calls you?
Have delays in speech and language or listening development?
Tend to look around outside to locate sound sources?
Find maintaining attention difficult
If we have challenges with sound localisation, you can also imagine how difficult it is to listen if there is any background noise. Imagine your child trying to listen to the teacher in the classroom when there are other people talking inside or outside the classroom. This skill, known as auditory figure-ground is well known to be compromised in many with listening and learning challenges.
Advanced Brain Technologies offer tools such as TAVS which assesses many of these skills as well as The Listening Program which is designed specifically to retrain the auditory system to better locate sound in space. A recent study on The Listening Program shows the impact this can have on improving this auditory figure-ground skill adding to the wide research base already available.
If your child has challenges with attention, listening and learning it is worth looking into whether they may have compromised sound localisation skills – these skills are developmental and can be improved.
Alan Heath is the Director of Learning Solutions and International Representative for Advanced Brain Technologies. He is the co-developer of The Movement Program and TAVS (Test of Auditory and Visual Skills)