[Smt-talk] Audio disability question

Mon Oct 6 09:23:41 PDT 2014

What a great conversation Amy Bauer's question has generated! I’m archiving the conversation here,  http://musicdisabilitystudies.wordpress.com/archived-conversations/ on the blog of the DISMUS interest group, for future reference.
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Jennifer Iverson, Ph.D.
Assistant Professor of Music Theory
University of Iowa
School of Music
2775 UCC
Iowa City, IA 52242

(319) 384-3365 (office)
jennifer-iverson at uiowa.edu (email)

From: Justin London <jlondon at carleton.edu<mailto:jlondon at carleton.edu>>
Date: Sunday, October 5, 2014 at 9:02 PM
To: David Bashwiner <david.bashwiner at gmail.com<mailto:david.bashwiner at gmail.com>>
Cc: "smt-talk at lists.societymusictheory.org<mailto:smt-talk at lists.societymusictheory.org>" <smt-talk at lists.societymusictheory.org<mailto:smt-talk at lists.societymusictheory.org>>
Subject: Re: [Smt-talk] Audio disability question

Many thanks to David Bashwiner for his thorough answer to Amy’s question—a fine “teachable moment”(!).

And just a note to second the gist of David’s summary: many of these studies involve what might, at best, be called “quasi musical stimuli,” and involve participants at vastly different stages of auditory development and enculturation (from newborns to geriatrics).  So, it is indeed murky just how this student’s “deafness in her left ear” (which, as David points out, may arise at any number of points in the auditory pathway) would affect her aural skills performance, which is not to say there isn’t some significant effect.

All best,
Justin

On Oct 5, 2014, at 2:56 PM, David Bashwiner <david.bashwiner at gmail.com<mailto:david.bashwiner at gmail.com>> wrote:

Amy,

I get the sense you're most interested in practical evidence, but I found myself intrigued with your question and thought I'd send you some slightly more theoretical thoughts. In short, I would say that while differences can be found in processing styles found in the left and right hemispheres (specifically for auditory processing), the differences are not black-and-white. I've grouped these thoughts into anatomical considerations, neuropsychological considerations, and music-specific neuro-cognitive considerations.

I suppose I should mention that I'm not an MD, so anything that piques your interest you should verify with someone who is.

Anatomical Considerations
One thing you mention having read is that "we use our left ears almost exclusively for" the purpose of "reproducing and recognizing pitch height." I don't have proof that this isn't true, but I personally would shy away from accepting it without further investigation (and I'd love to take a look at the article you mention). It is clear that, if you look at neural pathways from each ear to each side of the brain, you will find a favoring for contralateral information flow: i.e., a slight tendency for sounds coming in through the left ear to be processed by the right side of the brain, and vice versa. I say "favoring" and "slight," however, since the percentage ratio is not 100%-0% (as it is for vision), but is more like 60%-40% (at least to the best of my knowledge). There is, in addition, a significant amount of "cross-talk" across the hemispheres, at brainstem levels and via the corpus callosum in the neocortex. If you take a look at this figure<http://web.squ.edu.om/med-Lib/MED_CD/E_CDs/anesthesia/site/content/figures/3035F10.gif>, which traces the path of information flow from the left cochlea up the brainstem to the auditory cortex, you can see that most of the connections go to the contralateral side but that some do stay on the ipsilateral side. Thus, in theory at least, sound entering the right ear should be processed at least somewhat in the right auditory cortex.

It is worth noting that if your student is "deaf in her left ear," the deafness could conceivably be the result of damage at any one of these multiple points—ear drum, cochlea, auditory nerve, cochlear nucleus, inferior colliculus, auditory cortex, etc. It might be worth a visit to a neurologist or otolaryngologist to determine where origin of the deficit is. That visit could give you some clues on how to deal with her musical issues.

Neuropsychological Considerations
There is much debate regarding how music-specific the right hemisphere is, and how speech-specific the left hemisphere is. It seems that most researchers agree with a hypothesis advanced by Robert Zatorre and colleagues in around 2002<http://www.ncbi.nlm.nih.gov/pubmed/11849614> (dating at least back to Penhune et al. 1996<http://www.ncbi.nlm.nih.gov/pubmed/8921202>) that the left hemisphere is not specialized for the processing speech per se, but rather is specialized for the processing of rapid information flow. Music can be fast, but speech virtually always is. Similarly, distinctions in speech tend to be simple binaries, such as "was that /b/ or /p/?" The left side of the (auditory) brain thus appears to be specialized for rapidly resolving yes-no binaries, the right for indulging in the contemplation of spectral complexity. There is anatomical support for this as well: the left Heschl's gyrus (primary auditory cortex) has more white matter than gray, relative to the right HG—white matter translating to more myelination and hence faster transmission in neurons, but fewer neurons altogether. A recent study from Stefan Koelsch's lab<http://www.pnas.org/content/107/10/4758.short> reports that music-specific processing is biased toward the right hemisphere as early as a few hours after birth.

>From the above it should be clear that there's a general acknowledgement in the scientific community that the right and left sides of the brain (at least auditory cortices) do have different processing styles. Nevertheless, this does not translate directly to speech-perception on the left and music-perception on the right. In primates as well as humans, regions in both the right and left sides of the brain<http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3398142/> are specially sensitive to the vocal sounds of conspecifics. We process both speech and music simultaneously along multiple parallel channels, some subserved more by left-side networks, some more by right-side networks. Moreover, there's significant redundancy, such that whenever a right-side region shows activation for a given task, at least some activation (if less) is seen on the left as well. I don't have a paper I can cite on this, but that's my sense from my familiarity with the literature.

In sum, the right and left auditory cortices do seem to have different strengths, and hence different processing styles. But there's redundancy as well, with right side activations tending to be mirrored by left-side activations as well. The right and left auditory cortices are probably better thought to differ in degree rather than in kind.

Musico-Neurological Considerations
You wrote specifically with concerns about your student's ability to "reproduce and recognize pitch height." In neuroscience, this faculty has been broken up into two sub-faculties—assessing height generally, and assessing membership in a pitch class or scale degree. The former, in the neuroscience literature, is called height, the latter chroma. E.g., C4 and C5 differ in height but not in chroma.

Assessment of pitch height has been found to be a product of activity in a region just posterior to primary auditory cortex (on both sides of the brain), called the planum polare (PP). Assessment of pitch chroma has been found to be a product of activity in a region just anterior to primary auditory cortex, called the planum temporale (PT).

My guess is that pitch chroma identification is the issue your student is having the most trouble with, and thus that there might be an issue either with the functioning of the PT or with getting information to the PT. I also would not at all be surprised if the right-side PT were more important for this task than the left-side PT, and this could explain why your student's left-ear deafness might be an issue. But... I don't see any evidence for the right-side PT being more integral to this task than the left-side PT. Warren et al. (2003)<http://www.pnas.org/content/100/17/10038.short> were the first (to my knowledge) to dissociate the functioning of PT and PP, and to attribute chroma identification to PP.  In their paper, I don't see a significantly stronger involvement of the right PT than the left PT (but I may be missing something). You might consider sending them a note and seeing what they have to say about this. I also looked for more recent evidence about PP and pitch chroma but didn't turn up much (at least nothing that challenges the original theory or says anything new about lateralization). Here's a more up-to-date review<http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3098378/> of the the literature on the neurology of pitch perception generally, however, and these authors do indicate that many aspects of pitch perception are straightforwardly lateralized to the right hemisphere predominantly. I think a close read of that article could turn up some new leads.

Here's my summary.

1) I would say the neurology of the situation is relevant. I think it's great that your student showed you that study (please send it to me by the way!), and I also think any problem solving you continue to do can be usefully informed by understanding the neuroscience underlying pitch perception, chroma identification, and the connections between auditory cortex and the ears. As I said, I'm not an MD, but I'm more than happy to keep exchanging thoughts and be available for idea-bouncing-off.

2) I think a neurological and/or otolaryngological assessment would be a good investment in the student's musical future, given that it might help diagnose the problem better, and thus help you guide her education better.

3) Brian Wilson was deaf in one ear—his right—and seems to have had no problem understanding speech. Reciprocally, I would be somewhat surprised if deafness in the left ear necessarily meant difficulty resolving and reproducing pitch. But it is clear that the right brain has some privileged involvement in music cognition, and the right brain gets its input predominantly (but not exclusively) from the left ear. All of this just means that a medical exam would be worthwhile. If you get one, let me know, and I'll try to help sort out further issues.

I hope this helps!

David

On Thu, Oct 2, 2014 at 2:34 PM, Amy Bauer <abauer at uci.edu<mailto:abauer at uci.edu>> wrote:
Dear colleagues,

We have a very hard-working, gifted young pianist who cannot pass her aural skills sequence. She has bronchial pulmonary dispasia (which affects her ability to sight-sing). But her primary issue is almost total deafness in her left ear. She struggled for a long while to understand why she had absolutely no problems with speech or understanding speech, but had difficulty reproducing and recognizing pitch height. According to a recent research paper she shared with me, we use our left ears almost exclusively for that purpose, while using the right ear to decipher speech and syntactical relationships.

Has anyone dealt with a similar situation, or has anyone dealt with a situation where a student simply could not complete their aural skills requirement for medical reasons?

Thank you very much for any replies.
--

Amy Bauer
Associate Professor of Music Theory
3043 Contemporary Arts Center
Claire Trevor School of the Arts
University of California, Irvine
Irvine, CA 92697-2775

Tel: 949-824-6615<tel:949-824-6615>
Fax: 949-824-4914<tel:949-824-4914>
e-mail: abauer at uci.ed<mailto:abauer at uci.ed>
Department website<http://music.arts.uci.edu/content/amy-bauer>
Ligeti's Laments: Nostalgia, Exoticism and the Absolute<http://www.ashgate.com/isbn/9781409400417>

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--
David Bashwiner
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University of New Mexico
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