Can instrument training improve speech?
Greetings Dear Reader, from a chilly rainy Swiss morning. The weather has not been great in Luzern of late; autumn mist has descended from the mountains meaning that most days the city is coated in a low white blanket that hides the majestic scenery and waters the landscape. But every so often the sun appears and I’m reminded of how stunning this city can be. Luckily, even the mistiest of days can’t obscure the beauty of the lake and the old town.
This morning I turned my attention away from the rain and onto to a paper that had been staring at me every day since I downloaded it. A new paper by Ani Patel discussing how musical training may change the way that the brain processes speech (link at bottom of blog).
This paper is about ‘cross domain’ auditory plasticity – the idea that training in one domain (music) may trigger changes in neural processing of another related domain (speech). The new paper presents an extension of Ani’s OPERA hypothesis, a framework for understanding why music may influence our powers of speech.
This is a pretty dense paper, so let’s deal with one question at a time.
Does (instrumental) music influence speech processing in the brain?
First, we must limit ourselves to talking about instrumental training. Not singing lessons. This is not because singing couldn’t potentially improve speech (most evidence suggests it does) but because focusing on singing confuses our two interests (speech and music). Singing training involves heavy overlap with speech by virtue of the verbal content. So any impact of singing on speech processing could be partly explained by ‘within domain’ plasticity – and we are interested here in ‘cross domain’ plasticity.
The best type of evidence for the effect of music on speech is longitudinal (carried out over a long period – think months) and experimental. That means randomly assigning people to a music training vs. an active control activity (e.g. painting). If testing children then you also need a passive control group (one that takes no extra lessons) to rule out the effects of simple maturity on the brain.
One experimental study that Ani singles out in his paper is that of Bhide et al. (2013) who compared the impact of 2 months of rhythm training to 2 months training on phonological skills, and found that both resulted in comparable enhancements on a variety of speech and reading measures. The problem is that there are not many studies at present that adopt this kind of experimental approach, that use only instrumental training, and that measure brain changes.
The other form of evidence for the effect of music on speech comes from correlation studies, where people compare speech skills in musicians and non-musicians. For example, the study of Wong et al. (2007) who compared musicians and non-musicians Mandarin speech perception, and the excellent work of Nina Kraus’s lab. This kind of evidence is complementary to the experiments such as the one above, but it is not as theoretically strong as it can’t directly infer causation – that is, it can’t confirm the idea that only the musical training resulted in the differences in speech ability.
Why would music influence speech?
Quite apart from evidence that music may influence speech processing in the brain, we should be asking “Why would this happen?” That is what Ani’s OPERA hypothesis is about. OPERA predicts that music will drive changes to speech processing in the brain – that it will trigger cross domain plasticity – when the following 5 conditions are met:
1) O stands for Overlap – there must be anatomical overlap/shared networks in the brain
2) P stands for Precision – music must place higher demands on these shared networks than speech.
3) E stands for Emotion – the music must engage strong positive emotion
4) R stands for Repetition – the musical activities are repeated
5) A stands for Attention – the musical activities must engage the network associated with focused attention
You fulfill those 5 conditions and music will change the way the brain processes speech. That is the OPERA hypothesis. And like all good hypotheses, the job now is to test its predictions.
What is the extended OPERA hypothesis?
This new paper extends the original OPERA hypothesis and provides additional predictions to guide upcoming experiments. The original OPERA hypothesis focused only on the demands that musical training might place on sensory processing. The new extended hypothesis is applied to cognitive processes – namely auditory working memory and attention.
This shift better aligns OPERA with recent findings, particularly the work of groups associated with Nina Kraus and Mireille Besson. These studies have emphasized the impact of musical training on auditory attention and working memory, therefore Ani has laid out some ideas in this new paper as to why musical training might drive these processes to higher levels than that demanded by speech alone.
I have as special interest in auditory working memory (as you well know, Dear Reader) so I was particularly interested in ideas as to why music might drive this cognitive process to a higher level. I think there is scope to consider the development of executive functioning (EF) with sound – the ability to use multiple strategies with sound, and encode in multiple formats. Such a development would be akin to what we see in bilinguals (e.g. Bialystok et al., 2009).
From my own research experience, I think these sound-related EF processes are better in musicians and could be linked to their training (though this idea would, of course, have to be tested).
Previous studies have ruled out a difference in EF in young children who have received musical training (Schellenberg, 2011) but this fact does not eliminate the idea that we may see such a difference in adult musicians. After all, some effects of musical training may be seen in months, but some may take years to instantiate.
Where do we go from here?
In the new paper Ani lays out two pathways of research that may help test the predictions of OPERA and whether they can explain cross domain plasticity effects from music to speech processing. One is in testing musical training for cochlear implant users and the other is to test nonhuman models.
Of course, the major step would be now to test the simple predictions of OPERA in longitudinal, experimental human studies. Do we need OVERLAP to be in place to see an effect of music on speech processing in the brain? How do we conceive of a concept like PRECISION in a cognitive function like working memory? Are REPETITION and/or EMOTION really necessary as a precondition for an effect of music on speech processing?
These, and more, exciting questions for the future will move us towards a better understanding of how musical training might impact on our power of speech. And if we can better understand that theory then we are in better position to develop optimum pedagogic strategies as well as therapeutic techniques.
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