Decoding Auditory Processing

We are pleased to share the first in a monthly series of articles on auditory processing we’ll feature during the remainder of 2020. Our thanks to Alan Heath, founder and Director of Learning Solutions, and Advanced Brain Technologies representative in the UK, Ireland, and the United Arab Emirates, who authored this series.

This month’s article explains more about sound frequency and the importance of having the ability to access and understand the range of frequencies that the human ear can hear (20-20,000 Hz.) The ability to do so profoundly affects our ability to understand language.

Sound Frequency and Speech

When we think about listening, whether it is to a teacher’s voice in class or other environmental sounds such as a car or birdsong, we do not often consider the complexities involved in this seemingly simple process.

There are only four areas we need to think about when we consider fundamental auditory processing.

This blog is specifically about the frequency of speech sounds.

All natural sound, including your voice, is a complex mix of frequencies that need to be processed to be understood. For speech, the blend of frequencies is crucial to understand not just the words, but also the emotional content; is the person happy or angry? Your ear and brain need to be able to track the quickly changing frequencies to gain any understanding of what is being said, and then to decide what response is appropriate. Consider listening to a simple word like ‘cat.’ Here is the word mapped out visually using spectral analysis.

In the picture below, the frequency or pitch is on the vertical axis with time on the horizontal axis. The first burst of colour is the word ‘cat’ spoken at an average speed. The second is the word ‘cat’ with the ‘a’ lengthened. The separate sounds or phonemes of ‘c,’ ‘a,’ and ‘t’ are at different frequencies. You can see the ‘t’ comes after a tiny gap in sound. The red colour represents the low frequency of the vowel sound ‘a.’

Research has found (Sun et al., 2017) that “accurate pitch discrimination is critical to phonological processing,” which is our ability to listen to and manipulate the units of sound that comprise letters and words.

Referring again to our ‘cat,’ we find that the ‘t’ sound is at a much higher frequency, around 6000Hz than the ‘a,’ which is at perhaps 600Hz. To process sound at a basic level, we need to be able to process these fast changes in pitch in milliseconds.

It is well established that people with auditory processing problems, as well as those with Dyslexia, Autism, and other developmental challenges, may have difficulties in this area. Research shows that children with autism have difficulties tracking pitch (Otto-Meyer et al., 2019), and so do children with dyslexia (Ziegler et al., 2011).

If we have a hard time processing the swiftly changing frequencies in speech, we can also have challenges with listening, speech, and reading. If we cannot process speech quickly enough, it will often lead to social issues as we are unable to keep up with our peers.

Music can help here. The brain needs to develop the ability to process frequency, whether it is produced by an instrument or through speech – the fundamentals are the same. Learning an instrument or singing in a choir can develop auditory processing skills. Stringed instruments such as a violin or cello would be particularly beneficial since you need to place your fingers in a particular place on the string to produce a precise note. Brass and reed instruments such as the trombone or clarinet also require adjustments of the lips and breath to find the correct pitch.

There are also more therapeutically based (and often simpler!) options. The Listening Program® (TLP) was created to help anyone with this type of developmental delay to retrain their auditory system. TLP breaks down the frequency range humans can hear into specific bands to allow for subtle retraining of the auditory system.

Frequency or pitch perception can be improved and should be a vital component of a program for children with auditory processing problems, dyslexia, autism, and other developmental issues. Such training can help build the foundations of listening, attention, and speech.

ABOUT THE AUTHOR:
Alan Heath, BSC. (HONS.) PSYCH.
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)

References
Otto-Meyer, S., Krizman, J., WhiteSchwoch, T. and Kraus, N. (2018) Children with autism spectrum disorder have unstable neural responses to sound. Experimental Brain Research. Vol 236. Pp733-743. https://doi.org/10.1007/s00221-017-5164-4

Sun, Y., Lu, X., Ho, H, T. and Thompson, W. F. (2017) Pitch discrimination associated with phonological awareness: Evidence from congenital amusia. Scientific Reports | 7:44285 | https://www.sciencedirect.com/science/article/abs/pii/S0093934X11001908?via%3Dihub

Ziegler, J. C., Pech-Georgel, C., George, F. and Foxton, J, M. (2012) Global and local pitch perception in children with developmental dyslexia. Brain & Language. Vol 120 (3) pp. 265-270. https://doi.org/10.1016/j.bandl.2011.12.002