Auditory Processing Disorder: Can music help?

The other day I attended a fascinating symposium held at UCL. This type of meeting was new to me – a training session that combined useful information for those in research and in clinical practice. It was termed “Masterclass in Advanced Audiology: Auditory processing & Language Disorders: Insights from electrophysiology and imaging studies and applications to clinical practice”.

The Masterclass ran for three days (4^th-6^th May) but I attended the 5^th May session which was about understanding APD or Auditory Processing Disorder.  And very informative it was too. I could not write about all the talksbut for you , dear reader, I will summarise the work presented by Nina Kraus. She looked at understanding APD through the study of brainstem response, with a special nod to a possible future role of music therapy.

The British Society for Audiology has just released a new position statement on APD, which you can access here:  I will quote selectively from them to make sure my description of APD to you is as accurate as possible.

“APD is characterised by poor perception of both speech and non-speech sounds. Perception results from both sensory activation (via the ear) and neural processing that integrates this ‘bottom-up’ information with activity in other brain systems (e.g. vision, attention, memory)”.

“APD impacts on everyday life primarily through a reduced ability to listen, and so respond appropriately to sounds. The term ‘listening’ has been used to imply an active process while ‘hearing’ implies a more passive process; it is possible to hear without listening attentively”.

“APD is a collection of symptoms that usually co-occurs with other neurodevelopmental disorders. Like other such symptoms (poor language, literacy or attention, autism) APD is often found alongside other diagnoses.

If a child presents to a doctor with listening problems but then is shown to have normal hearing it is quite possible that they may go on to be diagnosed with APD. But it is also possible that children with language impairments or attention difficulties may receive APD diagnoses. Indeed, the co-occurrence of APD and SLI in particular is apparently very high.

 So what has all this to do with music, I hear you cry. This is where Nina Kraus comes in. Professor Kraus is a world expert in the study of activity in the brainstem, the ‘gateway to the brain’. She has carved out a niche studying auditory brain stem responses (ABRs) to speech and non-speech (including musical) sounds.

What is an ABR? When presented with sound the brain stem responds by producing an electrical signal that maintains the characteristics of the stimulus sound wave.  In Nina’s words:

“Timing, pitch and timbre are the basic information-bearing elements in music and speech. The auditory brainstem response represents a faithful reconstruction of these features and can be recorded in a non-invasive manner in human participants”

 In measuring the ABR (which you can do even if people are sleeping!), Professor Kraus’ research group have shown systematic, reliable differences between two populations compared to the normal listener: 1) Trained musicians (who are still active and play at least 2-3 times a week) and 2) Children with language difficulties (including dyslexia, SLI and, by extension, APD).  

Musicians show enhanced neural coding of sound waves as measured by ABR, reproducing a larger and more accurate representation than normal listeners. They even show a kind of hyper specialisation, with new findings soon to be published showing that a musician’s most faithful ABR comes when they hear their own instrument. In addition, we know that musicians often demonstrate better cognitive skills that relate to reading such as phonemic awareness and auditory working memory.

Poor readers by contrast, who typically have lower phonemic awareness and auditory working memory, show slower ABR responses. Their ABRs have good representation of the basic attributes of sound waves (i.e. the fundamental frequency) but poor representation of the more complex elements (i.e. the harmonics). These complex parts of the wave are more important for disambiguating sounds like consonants in spoken language.

So, if you put the two together, it seems music training strengthens a basic brain mechanism that may contribute to the understanding of language (it being impaired in those with poor reading/language skills).

These findings will pave the way for music interventions to be developed that will hopefully help poor readers develop their skills – and provide another reason why music education should not be lost from the National Curriculum (see my previous blog on this matter)

  And on a final note, you must, must, must visit Nina Kraus’ lab page. It is brilliant: Packed with useful information on her studies (including great slide shows), full access to her groups’ papers and a generous, open invitation to contact her for access to her MATLAB scripts or other tests. http://www.soc.northwestern.edu/brainvolts/