Hearing

A study involving 124 teenagers has found that those who were most accurate at tapping along with a metronome also showed the most consistent brain responses to a synthesized speech sound "da". The finding is consistent with previous research showing links between reading ability and beat-keeping ability, and between reading ability and the consistency of the brain's response to sound. The finding also provides more support for the benefits of music training for both language skills and auditory processing.

I’d suggest that it might be particularly important for second language learning, raising the intriguing question: if you have problems learning another language, could you improve your abilities by working on your sense of rhythm?

You can find out more about the work of the Auditory Neuroscience Laboratory at http://www.brainvolts.northwestern.edu.

http://www.eurekalert.org/pub_releases/2013-09/sfn-atm091313.php

http://www.eurekalert.org/pub_releases/2013-09/nu-tio091313.php

[3475] Tierney A, Kraus N. The Ability to Move to a Beat Is Linked to the Consistency of Neural Responses to Sound. The Journal of Neuroscience [Internet]. 2013 ;33(38):14981 - 14988. Available from: http://www.jneurosci.org/content/33/38/14981

A new study has found that errors in perceptual decisions occurred only when there was confused sensory input, not because of any ‘noise’ or randomness in the cognitive processing. The finding, if replicated across broader contexts, will change some of our fundamental assumptions about how the brain works.

The study unusually involved both humans and rats — four young adults and 19 rats — who listened to streams of randomly timed clicks coming into both the left ear and the right ear. After listening to a stream, the subjects had to choose the side from which more clicks originated.

The errors made, by both humans and rats, were invariably when two clicks overlapped. In other words, and against previous assumptions, the errors did not occur because of any ‘noise’ in the brain processing, but only when noise occurred in the sensory input.

The researchers supposedly ruled out alternative sources of confusion, such as “noise associated with holding the stimulus in mind, or memory noise, and noise associated with a bias toward one alternative or the other.”

However, before concluding that the noise which is the major source of variability and errors in more conceptual decision-making likewise stems only from noise in the incoming input (in this case external information), I would like to see the research replicated in a broader range of scenarios. Nevertheless, it’s an intriguing finding, and if indeed, as the researchers say, “the internal mental process was perfectly noiseless. All of the imperfections came from noise in the sensory processes”, then the ramifications are quite extensive.

The findings do add weight to recent evidence that a significant cause of age-related cognitive decline is sensory loss.

http://www.futurity.org/science-technology/dont-blame-your-brain-for-that-bad-decision/

[3376] Brunton BW, Botvinick MM, Brody CD. Rats and Humans Can Optimally Accumulate Evidence for Decision-Making. Science [Internet]. 2013 ;340(6128):95 - 98. Available from: http://www.sciencemag.org/content/340/6128/95

I’ve written before about the gathering evidence that sensory impairment, visual impairment and hearing loss in particular, is a risk factor for age-related cognitive decline and dementia. Now a large long-running study provides more support for the association between hearing loss and age-related cognitive decline.

The study involved 1,984 older adults (aged 75-84) whose hearing and cognition was tested at the start of the study, with cognitive performance again assessed three, five, and six years later.

Those with hearing loss showed significantly faster cognitive decline than those with normal hearing — some 30-40% faster (41% on the MMSE; 32% on the Digit Symbol Substitution Test), with rate directly related to the amount of hearing loss.

On average, older adults with hearing loss developed significant cognitive impairment 3.2 years sooner than those with normal hearing — a very significant difference indeed.

It has been suggested that increasing social isolation and loneliness may underlie some, if not all, of this association. It may also be that difficulties in hearing force the brain to devote too much of its resources to processing sound, leaving less for cognition. A third possibility is that some common factor underlies both hearing loss and cognitive decline — however, the obvious risk factors, such as high blood pressure, diabetes and stroke, were taken account of in the analysis.

The findings emphasize the importance of getting help for hearing difficulties, rather than regarding them as ‘natural’ in old age.

[3293] Lin FR, Yaffe K, Xia J, et al. Hearing loss and cognitive decline in older adults. JAMA Internal Medicine [Internet]. 2013 :1 - 7. Available from: http://dx.doi.org/10.1001/jamainternmed.2013.1868

Here’s an exciting little study, implying as it does that one particular aspect of information processing underlies much of the cognitive decline in older adults, and that this can be improved through training. No, it’s not our usual suspect, working memory, it’s something far less obvious: temporal processing.

In the study, 30 older adults (aged 65-75) were randomly assigned to three groups: one that received ‘temporal training’, one that practiced common computer games (such as Solitaire and Mahjong), and a no-activity control. Temporal training was provided by a trademarked program called Fast ForWord Language® (FFW), which was developed to help children who have trouble reading, writing, and learning.

The training, for both training groups, occupied an hour a day, four days a week, for eight weeks.

Cognitive assessment, carried out at the beginning and end of the study, and for the temporal training group again 18 months later, included tests of sequencing abilities (how quickly two sounds could be presented and still be accurately assessed for pitch or direction), attention (vigilance, divided attention, and alertness), and short-term memory (working memory span, pattern recognition, and pattern matching).

Only in the temporal training group did performance on any of the cognitive tests significantly improve after training — on the sequencing tests, divided attention, matching complex patterns, and working memory span. These positive effects still remained after 18 months (vigilance was also higher at the end of training, but this improvement wasn’t maintained).

This is, of course, only a small pilot study. I hope we will see a larger study, and one that compares this form of training against other computer training programs. It would also be good to see some broader cognitive tests — ones that are less connected to the temporal training. But I imagine that, as I’ve discussed before, an effective training program will include more than one type of training. This may well be an important component of such a program.

[3075] Szelag E, Skolimowska J. Cognitive function in elderly can be ameliorated by training in temporal information processing. Restorative Neurology and Neuroscience [Internet]. 2012 ;30(5):419 - 434. Available from: http://dx.doi.org/10.3233/RNN-2012-120240

Adding to the growing evidence for the long-term cognitive benefits of childhood music training, a new study has found that even a few years of music training in childhood has long-lasting benefits for auditory discrimination.

The study involved 45 adults (aged 18-31), of whom 15 had no music training, 15 had one to five years of training, and 15 had six to eleven years. Participants were presented with different complex sounds ranging in pitch while brainstem activity was monitored.

Brainstem response to the sounds was significantly stronger in those with any sort of music training, compared to those who had never had any music training. This was a categorical difference — years of training didn’t make a difference (although some minimal length may be required — only one person had only one year of training). However, recency of training did make a difference to brainstem response, and it does seem that some fading might occur over long periods of time.

This difference in brainstem response means that those with music training are better at recognizing the fundamental frequency (lowest frequency sound). This explains why music training may help protect older adults from hearing difficulties — the ability to discriminate fundamental frequencies is crucial for understanding speech, and for processing sound in noisy environments.

[3074] Skoe E, Kraus N. A Little Goes a Long Way: How the Adult Brain Is Shaped by Musical Training in Childhood. The Journal of Neuroscience [Internet]. 2012 ;32(34):11507 - 11510. Available from: http://www.jneurosci.org/content/32/34/11507

I’ve reported before on how London taxi drivers increase the size of their posterior hippocampus by acquiring and practicing ‘the Knowledge’ (but perhaps at the expense of other functions). A new study in similar vein has looked at the effects of piano tuning expertise on the brain.

The study looked at the brains of 19 professional piano tuners (aged 25-78, average age 51.5 years; 3 female; 6 left-handed) and 19 age-matched controls. Piano tuning requires comparison of two notes that are close in pitch, meaning that the tuner has to accurately perceive the particular frequency difference. Exactly how that is achieved, in terms of brain function, has not been investigated until now.

The brain scans showed that piano tuners had increased grey matter in a number of brain regions. In some areas, the difference between tuners and controls was categorical — that is, tuners as a group showed increased gray matter in right hemisphere regions of the frontal operculum, the planum polare, superior frontal gyrus, and posterior cingulate gyrus, and reduced gray matter in the left hippocampus, parahippocampal gyrus, and superior temporal lobe. Differences in these areas didn’t vary systematically between individual tuners.

However, tuners also showed a marked increase in gray matter volume in several areas that was dose-dependent (that is, varied with years of tuning experience) — the anterior hippocampus, parahippocampal gyrus, right middle temporal and superior temporal gyrus, insula, precuneus, and inferior parietal lobe — as well as an increase in white matter in the posterior hippocampus.

These differences were not affected by actual chronological age, or, interestingly, level of musicality. However, they were affected by starting age, as well as years of tuning experience.

What these findings suggest is that achieving expertise in this area requires an initial development of active listening skills that is underpinned by categorical brain changes in the auditory cortex. These superior active listening skills then set the scene for the development of further skills that involve what the researchers call “expert navigation through a complex soundscape”. This process may, it seems, involve the encoding and consolidating of precise sound “templates” — hence the development of the hippocampal network, and hence the dependence on experience.

The hippocampus, apart from its general role in encoding and consolidating, has a special role in spatial navigation (as shown, for example, in the London cab driver studies, and the ‘parahippocampal place area’). The present findings extend that navigation in physical space to the more metaphoric one of relational organization in conceptual space.

The more general message from this study, of course, is confirmation for the role of expertise in developing specific brain regions, and a reminder that this comes at the expense of other regions. So choose your area of expertise wisely!

I’ve spoken before about the association between hearing loss in old age and dementia risk. Although we don’t currently understand that association, it may be that preventing hearing loss also helps prevent cognitive decline and dementia. I have previously reported on how music training in childhood can help older adults’ ability to hear speech in a noisy environment. A new study adds to this evidence.

The study looked at a specific aspect of understanding speech: auditory brainstem timing. Aging disrupts this timing, degrading the ability to precisely encode sound.

In this study, automatic brain responses to speech sounds were measured in 87 younger and older normal-hearing adults as they watched a captioned video. It was found that older adults who had begun musical training before age 9 and engaged consistently in musical activities through their lives (“musicians”) not only significantly outperformed older adults who had no more than three years of musical training (“non-musicians”), but encoded the sounds as quickly and accurately as the younger non-musicians.

The researchers qualify this finding by saying that it shows only that musical experience selectively affects the timing of sound elements that are important in distinguishing one consonant from another, not necessarily all sound elements. However, it seems probable that it extends more widely, and in any case the ability to understand speech is crucial to social interaction, which may well underlie at least part of the association between hearing loss and dementia.

The burning question for many will be whether the benefits of music training can be accrued later in life. We will have to wait for more research to answer that, but, as music training and enjoyment fit the definition of ‘mentally stimulating activities’, this certainly adds another reason to pursue such a course.

I had to report on this quirky little study, because a few years ago I discovered Leonard Cohen’s gravelly voice and then just a few weeks ago had it trumped by Tom Waits — I adore these deep gravelly voices, but couldn’t say why. Now a study shows that woman are not only sensitive to male voice pitch, but this affects their memory.

In the first experiment, 45 heterosexual women were shown images of objects while listening to the name of the object spoken either by a man or woman. The pitch of the voice was manipulated to be high or low. After spending five minutes on a Sudoku puzzle, participants were asked to choose which of two similar but not identical versions of the object was the one they had seen earlier. After the memory test, participants were tested on their voice preferences.

Women strongly preferred the low pitch male voice and remembered objects more accurately when they have been introduced by the deeper male voice than the higher male voice (mean score for object recognition was 84.7% vs 77.8%). There was no significant difference in memory relating to pitch for the female voices (83.9% vs 81.7% — note that these are not significantly different from the score for the deeper male voice).

So is it that memory is enhanced for deeper male voices, or that it is impaired for higher male voices (performance on the female voices suggests the latter)? Or are both factors at play? To sort this out, the second experiment, involving a new set of 46 women, included unmanipulated male and female voices.

Once again, women were unaffected by the different variations of female voices. However, male voices produced a clear linear effect, with the unmanipulated male voices squarely in the middle of the deeper and higher versions. It appears, then, that both factors are at play: deepening a male voice enhances its memorability, while raising it impairs its memorability.

It’s thought that deeper voices are associated with more desirable traits for long-term male partners. Having a better memory for specific encounters with desirable men would allow women to compare and evaluate men according to how they might behave in different relationship contexts.

The voices used were supplied by four young adult men and four young adult women. Pitch was altered through software manipulation. Participants were told that the purpose of the experiment was to study sociosexual orientation and object preference. Contraceptive pill usage did not affect the women’s responses.

A number of studies have demonstrated the cognitive benefits of music training for children. Now research is beginning to explore just how long those benefits last. This is the second study I’ve reported on this month, that points to childhood music training protecting older adults from aspects of cognitive decline. In this study, 37 adults aged 45 to 65, of whom 18 were classified as musicians, were tested on their auditory and visual working memory, and their ability to hear speech in noise.

The musicians performed significantly better than the non-musicians at distinguishing speech in noise, and on the auditory temporal acuity and working memory tasks. There was no difference between the groups on the visual working memory task.

Difficulty hearing speech in noise is among the most common complaints of older adults, but age-related hearing loss only partially accounts for the problem.

The musicians had all begun playing an instrument by age 8 and had consistently played an instrument throughout their lives. Those classified as non-musicians had no musical experience (12 of the 19) or less than three years at any point in their lives. The seven with some musical experience rated their proficiency on an instrument at less than 1.5 on a 10-point scale, compared to at least 8 for the musicians.

Physical activity levels were also assessed. There was no significant difference between the groups.

The finding that visual working memory was not affected supports the idea that musical training helps domain-specific skills (such as auditory and language processing) rather than general ones.

An experiment with congenitally deaf cats has revealed how deaf or blind people might acquire other enhanced senses. The deaf cats showed only two specific enhanced visual abilities: visual localization in the peripheral field and visual motion detection. This was associated with the parts of the auditory cortex that would normally be used to pick up peripheral and moving sound (posterior auditory cortex for localization; dorsal auditory cortex for motion detection) being switched to processing this information for vision.

This suggests that only those abilities that have a counterpart in the unused part of the brain (auditory cortex for the deaf; visual cortex for the blind) can be enhanced. The findings also point to the plasticity of the brain. (As a side-note, did you know that apparently cats are the only animal besides humans that can be born deaf?)

The findings (and their broader implications) receive support from an imaging study involving 12 blind and 12 sighted people, who carried out an auditory localization task and a tactile localization task (reporting which finger was being gently stimulated). While the visual cortex was mostly inactive when the sighted people performed these tasks, parts of the visual cortex were strongly activated in the blind. Moreover, the accuracy of the blind participants directly correlated to the strength of the activation in the spatial-processing region of the visual cortex (right middle occipital gyrus). This region was also activated in the sighted for spatial visual tasks.

I’ve talked about the importance of labels for memory, so I was interested to see that a recent series of experiments has found that hearing the name of an object improved people’s ability to see it, even when the object was flashed onscreen in conditions and speeds (50 milliseconds) that would render it invisible. The effect was specific to language; a visual preview didn’t help.

Moreover, those who consider their mental imagery particularly vivid scored higher when given the auditory cue (although this association disappeared when the position of the object was uncertain). The researchers suggest that hearing the image labeled evokes an image of the object, strengthening its visual representation and thus making it visible. They also suggested that because words in different languages pick out different things in the environment, learning different languages might shape perception in subtle ways.

Older news items (pre-2010) brought over from the old website

Music training helps you hear better in noisy rooms

I’ve often talked about the benefits of musical training for cognition, but here’s a totally new benefit. A study involving 31 younger adults (19-32) with normal hearing has found that musicians (at least 10 years of music experience; music training before age 7; practicing more than 3 times weekly within previous 3 years) were significantly better at hearing and repeating sentences in increasingly noisy conditions, than the non-musicians. The number of years of music practice also correlated positively with better working memory and better tone discrimination ability. Hearing speech in noisy environments is of course difficult for everyone, but particularly for older adults, who are likely to have hearing and memory loss, and for poor readers.

[960] Parbery-Clark A, Skoe E, Lam C, Kraus N. Musician enhancement for speech-in-noise. Ear and Hearing [Internet]. 2009 ;30(6):653 - 661. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19734788

http://www.eurekalert.org/pub_releases/2009-08/nu-tum081709.php

Why it's hard to hear in a crowded room

New research helps explain why it’s difficult for those with impaired hearing to hear conversation involving several different people, particularly in a busy setting such as a restaurant or at a party. It appears that as you attend to a continuous auditory stream (such as one person speaking from one location), your attention gets refined and improved over time. However, if that person gets changing location, or if you have to focus on more than one speaker, then degradation occurs as attention gets switched and begins the process of building up performance again. It’s speculated that the same sort of attentional selectivity may occur with objects in a complex visual scene (think of “Where’s Wally”).

[1148] Best V, Ozmeral EJ, Kopco N, Shinn-Cunningham BG. Object continuity enhances selective auditory attention. Proceedings of the National Academy of Sciences [Internet]. 2008 ;105(35):13174 - 13178. Available from: http://www.pnas.org/content/early/2008/08/20/0803718105.abstract

http://www.eurekalert.org/pub_releases/2008-08/bu-mta082108.php

Memory impairment associated with sound processing disorder

Central auditory processing dysfunction refers to the situation where hearing in quiet settings is normal or near normal but is substantially impaired in the presence of competing noise or in other difficult listening situations. Such a problem is not helped by amplification and requires alternative rehabilitation strategies. Central auditory processing has been found to be impaired in those with dementia. Now a study comparing individuals with dementia, those with mild memory impairment but without a dementia diagnosis, and those without memory loss, has found that scores on central auditory processing tests were significantly lower in both the group with dementia and in the group with mild memory impairment, compared to controls.

[302] Gates GA, Anderson ML, Feeney PM, McCurry SM, Larson EB. Central auditory dysfunction in older persons with memory impairment or Alzheimer dementia. Archives of Otolaryngology--Head & Neck Surgery [Internet]. 2008 ;134(7):771 - 777. Available from: http://www.ncbi.nlm.nih.gov/pubmed/18645130

http://www.eurekalert.org/pub_releases/2008-07/jaaj-mia071708.php

Hearing loss in older adults may compromise cognitive resources for memory

A study involving older adults with good hearing and a group with mild-to-moderate hearing loss has found that even when older adults could hear words well enough to repeat them, their ability to memorize and remember these words was poorer in comparison to other individuals of the same age with good hearing. The researchers suggest that the effect of expending extra effort comprehending words means there are fewer cognitive resources for higher level comprehension. Working memory capacity tends to diminish as we age.

[394] Wingfield A, Tun PA, McCoy SL. Hearing Loss in Older Adulthood. Current Directions in Psychological Science [Internet]. 2005 ;14(3):144 - 148. Available from: http://dx.doi.org/10.1111/j.0963-7214.2005.00356.x

http://www.eurekalert.org/pub_releases/2005-08/bu-hli082905.php