ArticlePDF Available

Musical experience offsets age-related delays in neural timing

Authors:

Abstract and Figures

Aging disrupts neural timing, reducing the nervous system's ability to precisely encode sound. Given that the neural representation of temporal features is strengthened with musical training in young adults, can musical training offset the negative impact of aging on neural processing? By comparing auditory brainstem timing in younger and older musicians and nonmusicians to a consonant-vowel speech sound /da/. we document a musician's resilience to age-related delays in neural timing.
Content may be subject to copyright.
Musical experience offsets age-related delays in neural timing
Alexandra Parbery-Clark
a,b
, Samira Anderson
a,b
, Emily Hittner
a
, Nina Kraus
a,b,c,d,e,
*
a
Auditory Neuroscience Laboratory, Northwestern University, Evanston, IL
b
Communication Sciences, Northwestern University, Evanston, IL
c
Institute for Neuroscience, Northwestern University Interdepartmental Neuroscience Program, Chicago, IL
d
Departments of Neurobiology and Physiology, Northwestern University, Evanston, IL
e
Department of Otolaryngology, Northwestern University, Chicago, IL
Received 24 June 2011; received in revised form 24 October 2011; accepted 12 December 2011
Abstract
Aging disrupts neural timing, reducing the nervous system’s ability to precisely encode sound. Given that the neural representation of
temporal features is strengthened with musical training in young adults, can musical training offset the negative impact of aging on neural
processing? By comparing auditory brainstem timing in younger and older musicians and nonmusicians to a consonant-vowel speech sound
/da/. we document a musician’s resilience to age-related delays in neural timing.
© 2012 Elsevier Inc. All rights reserved.
Keywords: Aging; Auditory brainstem response; Plasticity; Music
1. Introduction
Along the auditory pathway, neurons respond to sound in
a stimulus-synchronized manner, with subcortical structures
displaying submillisecond temporal accuracy an order of
magnitude greater than other sensory systems (Frisina,
2001; Walton, 2010; Wang, 2007). This subcortical preci-
sion is important for capturing fast-changing acoustic tran-
sitions, such as those that characterize speech. However,
neural precision (Frisina and Walton, 2006) and auditory
temporal processing (Grose et al., 2006; Strouse et al. 1998)
decline with age, potentially contributing to the problems
older adults report for speech comprehension (Frisina,
2010; Gordon-Salant and Fitzgibbons, 1993).
Growing evidence from young adults indicates that mu-
sical training improves the neural representation of key
acoustic features important for speech perception, highlight-
ing the effects of lifelong training on the brain (Kraus and
Chandrasekaran, 2010). Here, we asked whether musical
experience offsets the decline in neural precision that occurs
during the natural aging process. To address this question, we
examined subcortical speech-evoked responses in a group of
younger (18 –32 years) and older (45– 65 years) normal-hear-
ing musicians and nonmusicians. Given their extensive en-
gagement with sound across their lifetimes, we hypothesized
that older musicians demonstrate less age-related decline in
subcortical temporal precision than older nonmusicians.
2. Methods
2.1. Subjects
Eighty-seven adults participated in this study: 50 younger
participants (18 –32 years, mean age: 23 4 years) and 37
older participants (46 65 years, mean age 56 5 years).
All subjects had normal hearing (see Fig. 1, octave frequen-
cies from 0.125 to 4 kHz bilaterally 20 dB HL, pure tone
average 10 dB HL), were native English speakers, and did
not report neurological or learning disorders, history of che-
motherapy or ototoxic medication, major surgeries, or head
trauma. All subjects had normal nonverbal IQ (younger: Test
of Nonverbal Intelligence; older: Abbreviated Wechsler’s
Adult Scale of Intelligence’s matrix reasoning subtest). Sub-
* Corresponding author at: Hugh Knowles Professor, Communication
Sciences, Neurobiology & Physiology, Otolaryngology, Auditory Neuro-
science Laboratory, Northwestern University, 2240 Campus Drive, Evanston,
IL 60208. Tel.: 1 847 491 3181; fax: 1 847 491 2523.
E-mail address: nkraus@northwestern.edu (N. Kraus). http://www.
brainvolts.northwestern.edu.
Neurobiology of Aging xx (2012) xxx
www.elsevier.com/locate/neuaging
0197-4580/$ – see front matter © 2012 Elsevier Inc. All rights reserved.
doi:10.1016/j.neurobiolaging.2011.12.015
jects gave informed written consent in accordance with the
Northwestern University’s Institutional Review Board.
All musicians (46: 26 younger, 20 older) started musical
training before the age of 9 and consistently engaged in mu-
sical activities (practice, performance, or teaching) for a min-
imum of 3 times a week throughout their lifetimes. Of the total
41 nonmusician subjects (24 younger, 17 older), 27 had no
musical training (15 younger, 12 older), whereas the remaining
14 (9 younger, 5 older) had fewer than 3 years of musical
experience. Within the younger and the older groups (see Table 1
for further group characteristics), musicians and nonmusicians did
not differ in age, hearing, sex, or IQ (all p0.1).
2.2. Subcortical response measures
To explore the effect of aging on a speech sound con-
taining both rapid formant transition changes and a steady-
state vowel, we chose to use a 170-ms 6-formant consonant-
vowel syllable /da/. This syllable has a steady fundamental
frequency (F
0
100 Hz) except for an initial 5 ms (onset)
burst. During the first 50 ms (transition between the stop
burst [d] and the vowel [a]), the lower 3 formants change
over time (F
1
: 400 –720 Hz; F
2
: 1700 –1240 Hz; F
3
: 2580 –
2500 Hz) but stabilize for the 120 ms steady-state vowel.
The upper 3 formants are constant throughout (F
4
: 3300 Hz;
F
5
: 3750 Hz; F
6
: 4900 Hz). Subcortical responses were differ-
entially recorded at a 20 kHz sampling rate by Ag–AgCl
electrodes in a vertical montage using Scan 4.3 (Compumed-
ics, Charlotte, NC) with an electrode contact impedance 5
k. Stimuli were presented binaurally at 80 dB SPL through
ER-3 insert earphones (Etymotic Research, Elk Grove Village,
IL) at a rate of 3.95 per second. Stimuli were presented in
alternating polarities, and responses were summed to limit the
inclusion of stimulus artifact and cochlear microphonic (Skoe
and Kraus, 2010). During the recording session (26 2
minutes), participants watched a silent, captioned movie of
their choice to facilitate a wakeful yet still state. Responses
were offline, band-pass filtered from 70 to 2000 Hz (12 dB
roll-off, zero phase-shift) using NeuroScan Edit 4.3 and ep-
oched from 40 to 213 ms (referenced to stimulus onset).
Responses with amplitudes beyond 35
V were considered
artifact and rejected, resulting in 6000 response trials for each
subject. Peak latencies corresponding to the onset (1 peak),
transition (4 peaks), and steady state (10 peaks) were identified
in the average responses by the first 3 authors blind to the
subjects’ group status.
3. Results
To investigate neural timing, we identified peaks in the
subcortical response generated by synchronous neural firing
to the speech syllable [da] (Fig. 2A). Aging differentially
delayed the neural response to the formant transition (30 –70
ms, 4 peaks), the most complex and information-bearing
portion of our stimulus, in musicians relative to nonmusi-
cians [2
Age
2
Musicianship
multivariate analysis of variance
(MANOVA); Interaction: F(1,83) 2.659, p0.039 (Fig.
2E); Age: F(1,83) 4.642, p0.002; Musicianship:
F(1,83) 6.016, p0.001]. Although younger and older
musicians exhibited equivalent response timing for the
formant transition (Fig. 2B) [F(1,83) 1.434, p0.240],
older nonmusicians demonstrated significantly later re-
sponse timing relative to younger nonmusicians [F(1,83)
4.304, p0.006 (Fig. 2C)]. Aging delayed the neural
response to the onset (one peak) of sound in both groups
equally [Interaction: F(1,83) 0.867, p0.354; Age:
Fig. 1. Mean pure-tone thresholds (average of right and left) for younger
and older musicians and nonmusicians from 125 to 8000 Hz. As expected
the older groups, despite clinically normal hearing, demonstrated higher
thresholds for all frequencies measured; however, within the younger and
older groups, the musicians and nonmusicians had equivalent hearing.
Error bars equal 1 standard error of measurement (SEM).
Table 1
Number of males and females in each subject group as well as the mean age and age range for each sex
Younger Older
Musicians Nonmusicians Musicians Nonmusicians
Females Males Females Males Females Males Females Males
Total 17 9 17 7 15 5 13 4
Mean age 22 23 22 24 55 55 58 57
Age range 18–32 18–30 18–30 21–27 47–65 45–63 45–61 51–65
2A. Parbery-Clark et al. / Neurobiology of Aging xx (2012) xxx
F(1,83) 40.045, p0.001; Musicianship: F(1,83)
5.643, p0.02 (Fig. 2D)]. Aging did not affect the neural
response to the vowel (70 –170 ms, 10 peaks) [Interaction:
F(1,83) 0.813, p0.616; Age: F(1,83) 0.757, p
0.669; Musicianship: F(1,83) 1.497, p0.158 (Fig.
2F)]. The main effect of musicianship observed for the neural
response to the onset and the transition was driven solely by
group differences in the older participants [Onset: Younger
(F(1,83) 1.530, p0.222); Older F(1,83) 3.739, p
0.061); Transition: Younger (F(1,83) 1.233, p0.311);
Older: (F(1,83) 6.206, p0.001)].
4. Discussion
In summary, our results show distinct effects of aging and
musicianship on the neural mechanisms responsible for encod-
ing the different components of a stimulus. Specifically, our
findings indicate that aging negatively impacts the encoding of
noise bursts (i.e. onset) and transient frequency sweeps (i.e.
formant transition) but not stable frequency components (i.e.
vowel). These outcomes are consistent with the demonstration
that stop consonant perception is compromised in older adults,
unlike vowel perception, which is minimally affected by age
(Ohde and Abou-Khalil, 2001). We also show that although
musicians and nonmusicians experience age-related delays in
onset timing, the most vulnerable portion of the speech-evoked
auditory brainstem response (Anderson et al., 2010; Cunning-
ham et al., 2002), musical experience mitigates the effects of
aging on the neural encoding of the formant transition.
That musical experience counteracts age-related delays
in subcortical response timing to the formant transition
reveals the biologically powerful impact of music on the
aging nervous system, raising the question: through which
neural mechanisms might musical experience be mediating
this effect? Inhibitory processes are potential candidates
Fig. 2. Musicians show less age-related neural delays than nonmusicians. (A) Average neural response (young musicians) to the speech stimulus [da] divided
into 3 regions based on stimulus characteristics: onset, formant transition, and steady-state vowel. (B, C) To facilitate visualization of the data, the peak
latencies are normalized. Normalization of the peak latencies was accomplished by subtracting the expected response timing based on stimulus characteristics and
neural lag (9 ms for the onset, 33, 43, 53, 63, etc. until 163 ms for the transition and steady state) from each individual’s corresponding peak response latency. This
resulted in a value between 1 and 1 with positive numbers indicating a delay in neural response timing and negative numbers indicating earlier neural response
timing relative to the expected response latency. (B) Younger and older musicians have equivalent neural timing except for the onset response. (C) Older
nonmusicians show an age-related shift in neural response timing for both the onset and transition. (D–F) Age Musicianship interaction plots. (D) No Age
Musicianship interaction in the onset. (E) Significant Age Musicianship interaction in the transition. (F) No Age Musicianship interaction in the steady
state.
3A. Parbery-Clark et al. / Neurobiology of Aging xx (2012) xxx
given their critical role in shaping neural response patterns
to temporally dynamic sounds like speech (Caspary et al.,
2002; Simon et al. 2004). A reduction in inhibitory recep-
tors occurs with age, fundamentally altering synaptic neu-
rochemistry and compromising the nervous system’s ability
to represent sound (Caspary et al., 2008). Auditory training
in aging rodents bolsters compromised inhibitory processes,
essentially reversing age-related deficits (Villers-Sidani et
al., 2010). We posit, therefore, that lifelong musical expe-
rience is analogous to a long-term auditory training pro-
gram, in that precise subcortical response timing is sus-
tained through the maintenance of intricately balanced
excitatory and inhibitory subcortical neural networks. Al-
though our results speak to the positive effect of musical
experience on the aging process, they also hold broader
significance: musical experience protects against age-re-
lated degradation in neural timing, highlighting the modifi-
able nature of these declines. These findings should encour-
age future research into other forms of training that promote
neural resilience across the lifespan.
Disclosure statements
None of the authors have any conflict of interest to report
that is relative to this manuscript. Northwestern University has
no contracts relating to this research through which it or any
other organization may stand to gain financially now or in the
future. No agreements of authors or their institutions exist that
could be seen as involving a financial interest in this work.
The data contained in this manuscript have not been
previously published, have not been submitted elsewhere,
and will not be submitted elsewhere while under consider-
ation at Neurobiology of Aging.
The experimental protocol was reviewed and approved
by Northwestern University’s Institutional Review Board.
All subjects provided written informed consent according to
principles set forth by Northwestern University’s Institu-
tional Review Board.
All authors have reviewed the contents of the manuscript
being submitted, approve of its contents, and validate the
accuracy of the data.
Acknowledgements
This work was supported by NSF-1057556 and NSF-
0842376. The authors thank Dana Strait, Erika Skoe, and
Trent Nicol for their helpful comments.
References
Anderson, S., Skoe, E., Chandrasekaran, B., Kraus, N., 2010. Neural timing is
linked to speech perception in noise. J. Neurosci. 30, 4922– 4926.
Caspary, D.M., Ling, L., Turner, J.G., Hughes, L.F., 2008. Inhibitory
neurotransmission, plasticity and aging in the mammalian central au-
ditory system. J. Exp. Biol. 211, 1781–1791.
Caspary, D.M., Palombi, P.S., Hughes, L.F., 2002. GABAergic inputs
shape responses to sinusoidally amplitude modulated stimuli in the
chinchilla inferior colliculus. Hear. Res. 168, 163–173.
Cunningham, J., Nicol, T., King, C.D., Zecker, S.G., Kraus, N., 2002.
Effects of noise and cue enhancement on neural responses to speech in
auditory midbrain, thalamus and cortex. Hear. Res. 169, 97–111.
Frisina, R.D., 2001. Subcortical neural coding mechanisms for auditory
temporal processing. Hear. Res. 158, 1–27.
Frisina, R.D., 2010. Aging changes in the central auditory system, in: Rees,
A., Palmer, A., (Eds.), Handbook of Auditory Science: the Auditory
Brain, Ch. 17, pp. 415– 436. Oxford University Press, Oxford.
Frisina, R.D., Walton, J.P., 2006. Age-related structural and functional
changes in the cochlear nucleus. Hear. Res. 217, 216 –233.
Gordon-Salant, S., Fitzgibbons, P.J., 1993. Temporal factors and speech
recognition performance in young and elderly listeners. J. Speech Hear.
Res. 36, 1276 –1285.
Grose, J.H., Hall, J.W., Buus, E., 2006. Temporal processing deficits in the
pre-senescent auditory system. J. Acoust. Soc. Am. 119, 2305–2315.
Kraus, N., Chandrasekaran, B., 2010. Music training for the development
of auditory skills. Nat. Rev. Neurosci. 11, 599 –605.
Ohde, R.N., Abou-Khalil, R., 2001. Age differences for stop-consonant
and vowel perception in adults. J. Acoust. Soc. Am. 110, 2156 –2166.
Simon, H., Frisina, R.D., Walton, J.P., 2004. Age reduces response latency
of mouse inferior colliculus neurons to AM sounds. J. Acoust. Soc.
Am. 116, 469 – 477.
Skoe, E., Kraus, N., 2010. Auditory brainstem response to complex sounds:
a tutorial. Ear. Hear. 31, 302–324.
Strouse, A., Ashmead, D.H., Ralph, N., Ohde, R.N., Grantham, D.W.,
1998. Temporal processing in the aging auditory system. J. Acoust.
Soc. Am. 104, 2385–2399.
Villers-Sidani, E., Alzghoul, L., Zhou, X., Simpson, K.L., Lin, R.C.,
Merzenich, M.M., 2010. Recovery of functional and structural age-
related changes in the rat primary auditory cortex with operant training.
Proc. Natl. Acad. Sci. U. S. A. 107, 13900 –13905.
Walton, J.P., 2010. Timing is everything: temporal processing deficits in
the aged auditory brainstem. Hear. Res. 264, 63– 69.
Wang, X., 2007. Neural coding strategies in auditory cortex. Hear. Res.
229, 81–93.
4A. Parbery-Clark et al. / Neurobiology of Aging xx (2012) xxx
... These senescent changes in central auditory processing seem to involve a reduction in neural phase locking with age (Leigh-Paffenroth and Fowler, 2006;Anderson et al., 2021). The physiological mechanism underlying this decrease in phase-locked neural activity remains unclear, but some hypotheses based on animal models suggest the involvement of decreased neural inhibition, increased firing variability due to neural noise and increased neural jitter (Anderson et al., 2012). ...
... These deficits could play a role in the hearing difficulties of older adults, as strength of pitch encoding has been found to correlate with speech in noise perception in children and older adults (Anderson et al., 2011(Anderson et al., , 2010. Age-related F0 encoding deficits were observed in the spectral amplitude (Skoe et al., 2015;Vander Werff and Burns, 2011), phase coherence (Anderson et al., 2012;Clinard et al., 2010), signal-to-response correlation and response signal-to-noise ratio (Clinard and Cotter, 2015;Mamo et al., 2016). Using a speech stimulus, similar deficits were also found at specific harmonics (Anderson et al., 2012;Mamo et al., 2016), spectral bands, or formants (Skoe et al., 2015;Vander Werff and Burns, 2011). ...
... Age-related F0 encoding deficits were observed in the spectral amplitude (Skoe et al., 2015;Vander Werff and Burns, 2011), phase coherence (Anderson et al., 2012;Clinard et al., 2010), signal-to-response correlation and response signal-to-noise ratio (Clinard and Cotter, 2015;Mamo et al., 2016). Using a speech stimulus, similar deficits were also found at specific harmonics (Anderson et al., 2012;Mamo et al., 2016), spectral bands, or formants (Skoe et al., 2015;Vander Werff and Burns, 2011). These findings suggest that aging could be linked to a central auditory processing deficit that affects the encoding of spectral acoustic cues. ...
Article
Full-text available
Older adults often present difficulties understanding speech that cannot be explained by age-related changes in sound audibility. Psychoacoustic and electrophysiologic studies have linked these suprathreshold difficulties to age-related deficits in the auditory processing of temporal and spectral sound information. These studies suggest the existence of an age-related temporal processing deficit in the central auditory system, but the existence of such deficit in the spectral domain remains understudied. The FFR is an electrophysiological evoked response that assesses the ability of the neural auditory system to reproduce the spectral and temporal patterns of a sound. The main goal of this short review is to investigate if the FFR can identify and measure spectral processing deficits in the elderly compared to younger adults (for both, without hearing loss or competing noise). Furthermore, we want to determine what stimuli and analyses have been used in the literature to assess the neural encoding of spectral cues in older adults. Almost all reviewed articles showed an age-related decline in the auditory processing of spectral acoustic information. Even when using different speech and non-speech stimuli, studies reported an age-related decline at the fundamental frequency, at the first formant, and at other harmonic components using different metrics, such as the response's amplitude, inter-trial phase coherence, signal-to-response correlation, and signal-to-noise ratio. These results suggest that older adults may present age-related spectral processing difficulties, but further FFR studies are needed to clarify the effect of advancing age on the neural encoding of spectral speech cues. Spectral processing research on aging would benefit from using a broader variety of stimuli and from rigorously controlling for hearing thresholds even in the absence of disabling hearing loss. Advances in the understanding of the effect of age on FFR measures of spectral encoding could lead to the development of new clinical tools, with possible applications in the field of hearing aid fitting.
... In older adults, music listening can boost various cognitive domains related to memory including autobiographical memory recall (El Haj et al., 2015), working memory (WM) (Chow et al., 2021), and semantic memory (Bottiroli et al., 2014). Relative to our interest in auditory processing, both long-and short-term music engagement in older adults has also been associated with neural and behavioral improvements in sensory and speech processing (e.g., Parbery-Clark et al., 2012;Alain et al., 2014Alain et al., , 2019Bidelman and Alain, 2015). In line with the arousal-and-mood hypothesis (Thompson et al., 2001;Husain et al., 2002), we have proposed that listening to autobiographically salient music may have the potential to improve short-term performance in certain cognitive domains, including speech processing, by improving positive affect and heightening arousal state (Chow et al., 2021). ...
Article
Full-text available
Emerging evidence suggests transcranial direct current stimulation (tDCS) can improve cognitive performance in older adults. Similarly, music listening may improve arousal and stimulate subsequent performance on memory-related tasks. We examined the synergistic effects of tDCS paired with music listening on auditory neurobehavioral measures to investigate causal evidence of short-term plasticity in speech processing among older adults. In a randomized sham-controlled crossover study, we measured how combined anodal tDCS over dorsolateral prefrontal cortex (DLPFC) paired with listening to autobiographically salient music alters neural speech processing in older adults compared to either music listening (sham stimulation) or tDCS alone. EEG assays included both frequency-following responses (FFRs) and auditory event-related potentials (ERPs) to trace neuromodulation-related changes at brainstem and cortical levels. Relative to music without tDCS (sham), we found tDCS alone (without music) modulates the early cortical neural encoding of speech in the time frame of ∼100–150 ms. Whereas tDCS by itself appeared to largely produce suppressive effects (i.e., reducing ERP amplitude), concurrent music with tDCS restored responses to those of the music+sham levels. However, the interpretation of this effect is somewhat ambiguous as this neural modulation could be attributable to a true effect of tDCS or presence/absence music. Still, the combined benefit of tDCS+music (above tDCS alone) was correlated with listeners’ education level suggesting the benefit of neurostimulation paired with music might depend on listener demographics. tDCS changes in speech-FFRs were not observed with DLPFC stimulation. Improvements in working memory pre to post session were also associated with better speech-in-noise listening skills. Our findings provide new causal evidence that combined tDCS+music relative to tDCS-alone (i) modulates the early (100–150 ms) cortical encoding of speech and (ii) improves working memory, a cognitive skill which may indirectly bolster noise-degraded speech perception in older listeners.
... These cognitive advantages among musically-trained individuals may continue into older age [17][18][19][20][21][22][23]. A recent meta-analysis analyzed 9 correlative studies and 4 experimental studies in musicians versus non-musicians age 59 and over [20]. ...
Article
Full-text available
Background As the global burden of dementia increases, the absence of treatment underscores the need for identification of factors that may improve cognitive reserve–the ability to stave off cognitive decline in old age. The beneficial association between musical instrument engagement and episodic memory has been identified in children, young adults, and older adults. Yet, previous studies in musical instrument engagement have rarely examined the potential for adolescence and adulthood exposures to independently improve cognition, nor have they been linked with the rate of memory decline over time in older adults. We investigated whether adolescent musical instrument engagement and continued musical instrument engagement over the adult life course were separately associated with higher episodic memory, as well as rate of decline in a large longitudinal cohort. Methods Data were from a prospective cohort of high school graduates from 1957. High school music engagement (HSME) was ascertained through graduate yearbooks and assessed as membership in musical performance groups. A questionnaire was used to assess musical engagement through adulthood (MEA) at ages 35, 55, and 65. The episodic memory score was composed of immediate and delayed recall task scores, and was assessed when participants were aged approximately 65 and 72 years old among 5,718 individuals. Linear mixed models were used to assess the association between music, and memory performance and decline over time. Results Of high school graduates who participated in the study, 38.1% played music in high school, and 21.1% played music in adulthood. While musical engagement was more common in those who played in childhood, 40% of those who played continuously as an adult did not play in high school. High HSME ( B = 0.348, p = 0.049) and continuous MEA ( B = 0.424, p = 0.012) were associated with higher memory scores at age 65 after covariate adjustment. When examining memory decline, the benefits of high HSME decreased over time ( B = -0.435, p = 0.048), while the rate of decline did not differ between MEA groups. Exploratory models revealed differential benefits for HSME and immediate recall, and MEA and delayed recall. Conclusion This study provides further evidence that musical engagement in childhood or adulthood is associated with non-musical cognitive reserve. These two exposures may act differentially in different domains of episodic memory. Further work is needed to determine the relationship between musicianship and the rate of cognitive decline.
... There is evidence that central processing can be improved with shortterm (Russo et al., 2010;Carcagno and Plack, 2011;Hornickel et al., 2012;Songet al., 2012) and long-term training with music or language (Parbery-Clark et al., 2009;Bidelman and Krishnan, 2010;Krizman et al., 2012a;Parbery-Clark et al., 2012) and that training can improve the cognition (Gazzaley et al., 2005;Smith et al., 2009;Berry et al., 2010). Anderson et al. (2013b) suggested that perceptual training that incorporates high cognitive demands may improve speech in noise perception either directly by training important factors such as memory and attention or indirectly by strengthening cortical-subcortical sound-to-meaning relationships. ...
Thesis
Abstract Background: Subjects with unilateral hearing loss (UHL) report difficulties in speech understanding in noise. Speech-evoked auditory brainstem response (S-ABR) provides cues for temporal and spectral encoding of speech in the brainstem. S-ABR recording in noise increases its sensitivity in evaluating auditory processing and related disorders. Objectives: Study speech encoding at the level of brainstem when the auditory system relies on one ear and the effect of noise on this encoding as well as its relation to subjective measures. Subjects and Method: This study included 2 groups: control group consisted of 15 adults with normal peripheral hearing (NH) and study group consisted of 30 adults with UHL. The study group was further subdivided into 2 subgroups; study subgroup A (SG A) consisted of 15 adults with right functioning ears and study subgroup B (SG B) consisted of 15 adults with left functioning ears. Arabic version of speech, spatial and qualities of hearing (SSQ) questionnaire and psychophysical speech in noise tests were applied on both studied groups. S-ABR in quiet and with ipsilateral noise was recorded in both groups using complex ABR advanced auditory research module. Results: In UHL, there was a statistically significant delay in the S-ABR onset and offset in noise compared to quiet. Moreover, quiet-noise (+5 SNR) correlation was significantly low compared to NH. Furthermore, pitch representation (F0 amplitude) was significantly degraded with noise in these subjects. Conclusion: Unilateral hearing loss affects speech processing at the level of brainstem in the presence of noise. Keywords: Speech-evoked auditory brainstem response (S-ABR), speech, spatial and qualities of hearing (SSQ) questionnaire, psychophysical speech in noise tests, unilateral hearing loss (UHL).
Article
Mild cognitive impairment (MCI) commonly results in more rapid cognitive and behavioral declines than typical aging. Individuals with MCI can exhibit impaired receptive speech abilities that may reflect neurophysiological changes in auditory-sensory processing prior to usual cognitive deficits. Benefits from current interventions targeting communication difficulties in MCI are limited. Yet, neuroplasticity associated with musical experience has been implicated in improving neural representations of speech and offsetting age-related declines in perception. Here, we asked whether these experience-dependent effects of musical experience might extend to aberrant aging and offer some degree of cognitive protection against MCI. During a vowel categorization task, we recorded single-channel EEGs in older adults with putative MCI to evaluate speech encoding across subcortical and cortical levels of the auditory system. Critically, listeners varied in their duration of formal musical experience (0-21 years). Musical experience sharpened temporal precision in auditory cortical responses suggesting musical experience produces more efficient processing of acoustic features by counteracting age-related neural delays. Additionally, robustness of brainstem responses predicted severity of cognitive decline suggesting early speech representations are sensitive to pre-clinical stages of cognitive impairment. Our results extend prior studies by demonstrating positive benefits of musical experience in older adults with emergent cognitive impairments.
Article
Hearing abilities decline with age, and one of the most commonly reported hearing issues in older adults is a difficulty understanding speech when there is loud background noise. Understanding speech in noise relies on numerous cognitive processes, including working memory, and is supported by numerous brain regions, including the motor and motor planning systems. Indeed, many working memory processes are supported by motor and premotor cortical regions. Interestingly, lifelong musicians and nonmusicians given music training over the course of weeks or months show an improved ability to understand speech when there is loud background noise. These benefits are associated with enhanced working memory abilities, and enhanced activity in motor and premotor cortical regions. Accordingly, it is likely that music training improves the coupling between the auditory and motor systems and promotes plasticity in these regions and regions that feed into auditory/motor areas. This leads to an enhanced ability to dynamically process incoming acoustic information, and is likely the reason that musicians and those who receive laboratory‐based music training are better able to understand speech when there is background noise. Critically, these findings suggest that music‐based forms of auditory rehabilitation are possible and should focus on tasks that promote auditory–motor interactions.
Article
Music is an art form that strongly affects people and can elicit many different emotions at the same time, including happiness, anxiety, sadness, and even ecstasy. What is it about music that causes such a strong reaction from each of us? Music engages many senses, which in turn can produce a multiplicity of responses and help create more extensive neuronal connections, as well as influence behaviour through structural and functional changes in the brain. Music-based interventions as a therapeutic tool in rehabilitation are becoming more common. It is said that the impact of music on the human body is positive. However, what impact does music have on the young nervous system, especially the affected one? This review presents the advantages and disadvantages of the use of music in paediatric neurology to treat dyslexia, cerebral palsy, and stroke, among others. Potential negative impacts such as musicogenic epilepsy and hallucinations will be discussed.
Conference Paper
Full-text available
Background : Many studies have shown conflicting conclusions about the effect of music on long and short term memory, as well as cognitive function. In this study we aim to investigate the effect of music on memory and the auditory cortex in all age groups.
Article
Full-text available
Background Some evidence suggests that young adults exhibit a selective laterality of auditory brainstem response (ABR) elicited with speech stimuli. Little is known about such an auditory laterality in older adults. Objective The aim of this study was to investigate possible asymmetric auditory brainstem processing between right and left ear presentation in older adults. Methods Sixty-two older adults presenting with normal hearing thresholds according to their age and who were native speakers of Quebec French participated in this study. ABR was recorded using click and a 40-ms /da/ syllable. ABR was elicited through monaural right and monaural left stimulation. Latency and amplitude for click-and speech-ABR components were compared between right and left ear presentations. In addition, for the /da/ syllable, a fast Fourier transform analysis of the sustained frequency-following response (FFR) of the vowel was performed along with stimulus-to-response and right-left ear correlation analyses. Results No significant differences between right and left ear presentation were found for amplitudes and latencies of the click-ABR components. Significantly shorter latencies for right ear presentation as compared to left ear presentation were observed for onset and offset transient components (V, A and O), sustained components (D and E), and voiced transition components (C) of the speech-ABR. In addition, the spectral amplitude of the fundamental frequency (F0) was significantly larger for the left ear presentation than the right ear presentation. Conclusions Results of this study show that older adults with normal hearing exhibit symmetric encoding for click stimuli at the brainstem level between the right and left ear presentation. However, they present with brainstem asymmetries for the encoding of selective stimulus components of the speech-ABR between the right and left ear presentation. The right ear presentation of a /da/ syllable elicited reduced neural timing for both transient and sustained components compared to the left ear. Conversely, a stronger left ear F0 encoding was observed. These findings suggest that at a preattentive, sensory stage of auditory processing, older adults lateralize speech stimuli similarly to young adults.
Preprint
Full-text available
Mild cognitive impairment (MCI) commonly impacts older adults resulting in more rapid cognitive and behavioral declines than typical aging. Individuals with MCI can exhibit impaired receptive speech abilities that may reflect neurophysiological changes in auditory-sensory processing prior to usual cognitive deficits. Benefits from current interventions targeting communication difficulties in MCI are limited. Yet, neuroplasticity associated with musical experience has been implicated in improving neural representations of speech and offsetting age-related declines in perception. Here, we asked whether these experience-dependent effects of musicianship might extend to aberrant aging and offer some degree of cognitive protection against MCI. During a vowel categorization task, we recorded single-channel EEGs in older adults with putative MCI to evaluate speech encoding across subcortical and cortical levels of the auditory system. Critically, listeners varied in their duration of formal musical training experience (0-21 years). Older musicians exhibited sharpened temporal precision in auditory cortical responses suggesting musical experience produces more efficient processing of acoustic features by offsetting age-related neural delays. Additionally, we found robustness of brainstem responses predicted severity of cognitive decline suggesting early speech representations are sensitive to pre-clinical stages of cognitive impairment. Our preliminary results extend prior studies by demonstrating positive benefits of musical experience in older adults with emergent cognitive impairments.
Article
Full-text available
The effects of music training in relation to brain plasticity have caused excitement, evident from the popularity of books on this topic among scientists and the general public. Neuroscience research has shown that music training leads to changes throughout the auditory system that prime musicians for listening challenges beyond music processing. This effect of music training suggests that, akin to physical exercise and its impact on body fitness, music is a resource that tones the brain for auditory fitness. Therefore, the role of music in shaping individual development deserves consideration.
Article
Full-text available
Cognitive decline is a virtually universal aspect of the aging process. However, its neurophysiological basis remains poorly understood. We describe here more than 20 age-related cortical processing deficits in the primary auditory cortex of aging versus young rats that appear to be strongly contributed to by altered cortical inhibition. Consistent with these changes, we recorded in old rats a decrease in parvalbumin-labeled inhibitory cortical neurons. Furthermore, old rats were slower to master a simple behavior, with learning progressions marked by more false-positive responses. We then examined the effect of intensive auditory training on the primary auditory cortex in these aged rats by using an oddball discrimination task. Following training, we found a nearly complete reversal of the majority of previously observed functional and structural cortical impairments. These findings suggest that age-related cognitive decline is a tightly regulated plastic process, and demonstrate that most of these age-related changes are, by their fundamental nature, reversible.
Article
Full-text available
Measures of monaural temporal processing and binaural sensitivity were obtained from 12 young (mean age = 26.1 years) and 12 elderly (mean age = 70.9 years) adults with clinically normal hearing (pure-tone thresholds < or = 20 dB HL from 250 to 6000 Hz). Monaural temporal processing was measured by gap detection thresholds. Binaural sensitivity was measured by interaural time difference (ITD) thresholds. Gap and ITD thresholds were obtained at three sound levels (4, 8, or 16 dB above individual threshold). Subjects were also tested on two measures of speech perception, a masking level difference (MLD) task, and a syllable identification/discrimination task that included phonemes varying in voice onset time (VOT). Elderly listeners displayed poorer monaural temporal analysis (higher gap detection thresholds) and poorer binaural processing (higher ITD thresholds) at all sound levels. There were significant interactions between age and sound level, indicating that the age difference was larger at lower stimulus levels. Gap detection performance was found to correlate significantly with performance on the ITD task for young, but not elderly adult listeners. Elderly listeners also performed more poorly than younger listeners on both speech measures; however, there was no significant correlation between psychoacoustic and speech measures of temporal processing. Findings suggest that age-related factors other than peripheral hearing loss contribute to temporal processing deficits of elderly listeners.
Article
This article examines age-related changes in the central auditory system from anatomical and neurochemical vantage points, and then the functional consequences of these structural changes are presented in the context of human perception and the underlying physiology of animal model systems. Neural processing in the central auditory system is dependent on the magnitude and timing of excitatory and inhibitory inputs to auditory neurons. Recent evidence suggests that there may be aging changes in other neurotransmitters at the level of the inferior colliculus. The molecular, anatomical, and neurochemical changes occurring with age in the auditory system have functional consequences for central auditory sound processing. Many of these are due to reduced cochlear outputs with age, and others appear to be somewhat independent of these peripheral changes, in line with neurodegenerative deficits of the aging brain. The article reveals that plasticity in the central auditory system often occurs well into old age, which is interesting from the perspectives of both basic neuroscience and future clinical interventions.
Article
Measures of monaural temporal processing and binaural sensitivity were obtained from 12 young (mean age=26.1 years ) and 12 elderly (mean age=70.9 years ) adults with clinically normal hearing (pure-tone thresholds ⩽20 dB HL from 250 to 6000 Hz). Monaural temporal processing was measured by gap detection thresholds. Binaural sensitivity was measured by interaural time difference(ITD) thresholds. Gap and ITD thresholds were obtained at three sound levels (4, 8, or 16 dB above individual threshold). Subjects were also tested on two measures of speech perception, a masking level difference (MLD) task, and a syllable identification/discrimination task that included phonemes varying in voice onset time (VOT). Elderly listeners displayed poorer monaural temporal analysis (higher gap detection thresholds) and poorer binaural processing (higher ITD thresholds) at all sound levels. There were significant interactions between age and sound level, indicating that the age difference was larger at lower stimulus levels. Gap detection performance was found to correlate significantly with performance on the ITD task for young, but not elderly adult listeners. Elderly listeners also performed more poorly than younger listeners on both speechmeasures; however, there was no significant correlation between psychoacoustic and speechmeasures of temporal processing. Findings suggest that age-related factors other than peripheral hearing loss contribute to temporal processing deficits of elderly listeners.
Article
Understanding speech in background noise is challenging for every listener, including those with normal peripheral hearing. This difficulty is attributable in part to the disruptive effects of noise on neural synchrony, resulting in degraded representation of speech at cortical and subcortical levels as reflected by electrophysiological responses. These problems are especially pronounced in clinical populations such as children with learning impairments. Given the established effects of noise on evoked responses, we hypothesized that listening-in-noise problems are associated with degraded processing of timing information at the brainstem level. Participants (66 children; ages, 8-14 years; 22 females) were divided into groups based on their performance on clinical measures of speech-in-noise (SIN) perception and reading. We compared brainstem responses to speech syllables between top and bottom SIN and reading groups in the presence and absence of competing multitalker babble. In the quiet condition, neural response timing was equivalent between groups. In noise, however, the bottom groups exhibited greater neural delays relative to the top groups. Group-specific timing delays occurred exclusively in response to the noise-vulnerable formant transition, not to the more perceptually robust, steady-state portion of the stimulus. These results demonstrate that neural timing is disrupted by background noise and that greater disruptions are associated with the inability to perceive speech in challenging listening conditions.
Article
This summary article reviews the literature on neural correlates of age-related changes in temporal processing in the auditory brainstem. Two types of temporal processing dimensions are considered, (i) static, which can be measured using a gap detection or forward masking paradigms, and (ii) dynamic, which can be measured using amplitude and frequency modulation. Corresponding data from physiological studies comparing neural responses from young and old animals using acoustic stimuli as silent gaps-in-noise, amplitude modulation, and frequency modulation are considered in relation to speech perception. Evidence from numerous investigations indicates an age-related decline in encoding of temporal sound features which may be a contributing factor to the deficits observed in speech recognition in many elderly listeners.
Article
This tutorial provides a comprehensive overview of the methodological approach to collecting and analyzing auditory brain stem responses to complex sounds (cABRs). cABRs provide a window into how behaviorally relevant sounds such as speech and music are processed in the brain. Because temporal and spectral characteristics of sounds are preserved in this subcortical response, cABRs can be used to assess specific impairments and enhancements in auditory processing. Notably, subcortical auditory function is neither passive nor hardwired but dynamically interacts with higher-level cognitive processes to refine how sounds are transcribed into neural code. This experience-dependent plasticity, which can occur on a number of time scales (e.g., life-long experience with speech or music, short-term auditory training, on-line auditory processing), helps shape sensory perception. Thus, by being an objective and noninvasive means for examining cognitive function and experience-dependent processes in sensory activity, cABRs have considerable utility in the study of populations where auditory function is of interest (e.g., auditory experts such as musicians, and persons with hearing loss, auditory processing, and language disorders). This tutorial is intended for clinicians and researchers seeking to integrate cABRs into their clinical or research programs.
Article
This study investigated factors that contribute to deficits of elderly listeners in recognizing speech that is degraded by temporal waveform distortion. Young and elderly listeners with normal hearing sensitivity and with mild-to-moderate, sloping sensorineural hearing losses were evaluated. Low-predictability (LP) sentences from the Revised Speech Perception in Noise test (R-SPIN) (Bilger, Nuetzel, Rabinowitz, & Rzeczkowski, 1984) were presented to subjects in undistorted form and in three forms of distortion: time compression, reverberation, and interruption. Percent-correct recognition scores indicated that age and hearing impairment contributed independently to deficits in recognizing all forms of temporally distorted speech. In addition, subjects' auditory temporal processing abilities were assessed on duration discrimination and gap detection tasks. Canonical correlation procedures showed that some of the suprathreshold temporal processing measures, especially gap duration discrimination, contributed to the ability to recognize reverberant speech. The overall conclusion is that age-related factors other than peripheral hearing loss contribute to diminished speech recognition performance of elderly listeners.
Article
Biologically relevant sounds such as speech, animal vocalizations and music have distinguishing temporal features that are utilized for effective auditory perception. Common temporal features include sound envelope fluctuations, often modeled in the laboratory by amplitude modulation (AM), and starts and stops in ongoing sounds, which are frequently approximated by hearing researchers as gaps between two sounds or are investigated in forward masking experiments. The auditory system has evolved many neural processing mechanisms for encoding important temporal features of sound. Due to rapid progress made in the field of auditory neuroscience in the past three decades, it is not possible to review all progress in this field in a single article. The goal of the present report is to focus on single-unit mechanisms in the mammalian brainstem auditory system for encoding AM and gaps as illustrative examples of how the system encodes key temporal features of sound. This report, following a systems analysis approach, starts with findings in the auditory nerve and proceeds centrally through the cochlear nucleus, superior olivary complex and inferior colliculus. Some general principles can be seen when reviewing this entire field. For example, as one ascends the central auditory system, a neural encoding shift occurs. An emphasis on synchronous responses for temporal coding exists in the auditory periphery, and more reliance on rate coding occurs as one moves centrally. In addition, for AM, modulation transfer functions become more bandpass as the sound level of the signal is raised, but become more lowpass in shape as background noise is added. In many cases, AM coding can actually increase in the presence of background noise. For gap processing or forward masking, coding for gaps changes from a decrease in spike firing rate for neurons of the peripheral auditory system that have sustained response patterns, to an increase in firing rate for more central neurons with transient responses. Lastly, for gaps and forward masking, as one ascends the auditory system, some suppression effects become quite long (echo suppression), and in some stimulus configurations enhancement to a second sound can take place.