Aging, hearing acuity, and the attentional costs of effortful listening

Effects of Aging and Adult-Onset Hearing Loss on Cortical Auditory Regions

Hearing loss is a common feature in human aging. It has been argued that dysfunctions in central processing are important contributing factors to hearing loss during older age. Aging also has well documented consequences for neural structure and function, but it is not clear how these effects interact with those that arise as a consequence of hearing loss. This paper reviews the effects of aging and adult-onset hearing loss in the structure and function of cortical auditory regions. The evidence reviewed suggests that aging and hearing loss result in atrophy of cortical auditory regions and stronger engagement of networks involved in the detection of salient events, adaptive control and re-allocation of attention. These cortical mechanisms are engaged during listening in effortful conditions in normal hearing individuals. Therefore, as a consequence of aging and hearing loss, all listening becomes effortful and cognitive load is constantly high, reducing the amount of available cognitive resources. This constant effortful listening and reduced cognitive spare capacity could be what accelerates cognitive decline in older adults with hearing loss.

Safety and outcomes of cochlear implantation in the elderly: A review of recent literature

Global demographic changes related to longevity are leading to increasing numbers of the elderly, for whom hearing loss is a significant cause of morbidity and disability. Once met with reticence, severely hearing impaired older adults are increasingly being considered for cochlear implantation (CI). Significant data indicate that CI in the elderly population is safe, well-tolerated, and effective. Risks from CI surgery and anesthesia are low and generally comparable to rates in other age groups. Outcomes studies regarding CI in older adults have shown excellent improvements to speech perception, quality of life, and even cognition. Overall, currently available data suggests that advanced age should not, in itself, be considered a barrier to implantation. This review paper will highlight selected articles from recent medical literature regarding the safety and efficacy of CI in the elderly population.

Perception and Cognition in the Ageing Brain: A Brief Review of the Short- and Long-Term Links between Perceptual and Cognitive Decline

Ageing is associated with declines in both perception and cognition. We review evidence for an interaction between perceptual and cognitive decline in old age. Impoverished perceptual input can increase the cognitive difficulty of tasks, while changes to cognitive strategies can compensate, to some extent, for impaired perception. While there is strong evidence from cross-sectional studies for a link between sensory acuity and cognitive performance in old age, there is not yet compelling evidence from longitudinal studies to suggest that poor perception causes cognitive decline, nor to demonstrate that correcting sensory impairment can improve cognition in the longer term. Most studies have focused on relatively simple measures of sensory (visual and auditory) acuity, but more complex measures of suprathreshold perceptual processes, such as temporal processing, can show a stronger link with cognition. The reviewed evidence underlines the importance of fully accounting for perceptual deficits when investigating cognitive decline in old age.

Autonomic Nervous System Responses During Perception of Masked Speech may Reflect Constructs other than Subjective Listening Effort

Typically, understanding speech seems effortless and automatic. However, a variety of factors may, independently or interactively, make listening more effortful. Physiological measures may help to distinguish between the application of different cognitive mechanisms whose operation is perceived as effortful. In the present study, physiological and behavioral measures associated with task demand were collected along with behavioral measures of performance while participants listened to and repeated sentences. The goal was to measure psychophysiological reactivity associated with three degraded listening conditions, each of which differed in terms of the source of the difficulty (distortion, energetic masking, and informational masking), and therefore were expected to engage different cognitive mechanisms. These conditions were chosen to be matched for overall performance (keywords correct), and were compared to listening to unmasked speech produced by a natural voice. The three degraded conditions were: (1) Unmasked speech produced by a computer speech synthesizer, (2) Speech produced by a natural voice and masked byspeech-shaped noise and (3) Speech produced by a natural voice and masked by two-talker babble. Masked conditions were both presented at a -8 dB signal to noise ratio (SNR), a level shown in previous research to result in comparable levels of performance for these stimuli and maskers. Performance was measured in terms of proportion of key words identified correctly, and task demand or effort was quantified subjectively by self-report. Measures of psychophysiological reactivity included electrodermal (skin conductance) response frequency and amplitude, blood pulse amplitude and pulse rate. Results suggest that the two masked conditions evoked stronger psychophysiological reactivity than did the two unmasked conditions even when behavioral measures of listening performance and listeners’ subjective perception of task demand were comparable across the three degraded conditions.

Hearing loss and cognition in the Busselton Baby Boomer cohort: An epidemiological study

OBJECTIVES/HYPOTHESIS

To determine the relationship between peripheral hearing loss (HL) in baby boomers (better-ear measure) and cognitive function, taking into account the impact of depression or cognitive reserve on this relationship and exploring binaural hearing.

STUDY DESIGN

A prospective, epidemiology study.

METHODS

Data from 1,969 participants aged 45 to 66 years were collected in the Busselton Healthy Ageing Study. Participants were assessed using pure-tone air-conduction thresholds at octave frequencies (250; 500; 1,000; 2,000; 4,000; and 8,000 Hz). Hearing loss was grouped using 1) pure-tone averages across 4 frequencies (500 to 4000Hz) in the better ear (BE4FA) or 2) latent profile analysis (LPA) using all thresholds from both ears. Cognition was tested with the Cognitive Drug Research System, verbal fluency, and National Adult Reading Test (premorbid-IQ). Regression was used to determine the impact of HL relative to no HL on age and education-adjusted cognition, controlling for mood, sex, and premorbid-IQ.

RESULTS

According to BE4FA, 4.7% had mild (26-40 dB) HL; 0.8% had moderate (41-60 dB) HL; and 0.3% had severe (61-80 dB) HL. Based on the LPA, 20.5% had high-frequency HL; 7.8% had mid- to high-frequency HL; and 1.9% had significant HL across all frequencies. The HL group was not a predictor of cognitive performance in any domain using BE4FA and explained just 0.5% and 0.4% of variance in continuity-of-attention and speed-of-memory retrieval using LPA. Critically, those with the worst hearing did not differ cognitively from those with the best.

CONCLUSION

Hearing loss is not an important determinant of contemporaneous attention, memory, or executive function in middle-aged adults once age, education, depression, cognitive reserve, and sex are controlled.

LEVEL OF EVIDENCE

4. Laryngoscope, 126:2367-2375, 2016.

The Effects of Aging on the Components of Auditory - Verbal Short-Term Memory

This study aimed at exploring the effects of aging on the multiple components of the auditory-verbal short-term memory (STM). Participants of 45-54, 55-64, 65-74 and 75-84 years of age were presented STM tasks assessing short-term retention of order and item information, and of phonological and lexical-semantic information separately. Because older participants often present reduced hearing levels, we sought to control for an effect of hearing status on performance on STM tasks. Participants' hearing thresholds were measured with a pure-tone audiometer. The results showed age-related effects on all STM components. However, after hearing status was controlled for in analyses of covariance, the age-related differences became non-significant for all STM processes. The fact that age-related hearing loss may in large part explain decreases in performance on STM tasks with aging is discussed.

Changes of the directional brain networks related with brain plasticity in patients with long-term unilateral sensorineural hearing loss

Previous studies often report that early auditory deprivation or congenital deafness contributes to cross-modal reorganization in the auditory-deprived cortex, and this cross-modal reorganization limits clinical benefit from cochlear prosthetics. However, there are inconsistencies among study results on cortical reorganization in those subjects with long-term unilateral sensorineural hearing loss (USNHL). It is also unclear whether there exists a similar cross-modal plasticity of the auditory cortex for acquired monaural deafness and early or congenital deafness. To address this issue, we constructed the directional brain functional networks based on entropy connectivity of resting-state functional MRI and researched changes of the networks. Thirty-four long-term USNHL individuals and seventeen normally hearing individuals participated in the test, and all USNHL patients had acquired deafness. We found that certain brain regions of the sensorimotor and visual networks presented enhanced synchronous output entropy connectivity with the left primary auditory cortex in the left long-term USNHL individuals as compared with normally hearing individuals. Especially, the left USNHL showed more significant changes of entropy connectivity than the right USNHL. No significant plastic changes were observed in the right USNHL. Our results indicate that the left primary auditory cortex (non-auditory-deprived cortex) in patients with left USNHL has been reorganized by visual and sensorimotor modalities through cross-modal plasticity. Furthermore, the cross-modal reorganization also alters the directional brain functional networks. The auditory deprivation from the left or right side generates different influences on the human brain.

How older adults use cognition in sentence-final word recognition

This study examined the effects of executive control and working memory on older adults' sentence-final word recognition. The question we addressed was the importance of executive functions to this process and how it is modulated by the predictability of the speech material. To this end, we tested 173 neurologically intact adult native English speakers aged 55-84 years. Participants were given a sentence-final word recognition test in which sentential context was manipulated and sentences were presented in different levels of babble, and multiple tests of executive functioning assessing inhibition, shifting, and efficient access to long-term memory, as well as working memory. Using a generalized linear mixed model, we found that better inhibition was associated with higher accuracy in word recognition, while increased age and greater hearing loss were associated with poorer performance. Findings are discussed in the framework of semantic control and are interpreted as supporting a theoretical view of executive control which emphasizes functional diversity among executive components.

A Comparison of Self-Report and Audiometric Measures of Hearing and Their Associations With Functional Outcomes in Older Adults

OBJECTIVE

The aim was to investigate whether associations of hearing impairment (HI) with functional outcomes in older adults differ when using self-report versus pure-tone audiometry.

METHOD

We examined 1,669 participants ≥70 years in National Health and Examination Survey from 2005-2006 and 2009-2010 whose hearing was assessed by self-report and pure-tone audiometry. We explored functional outcomes associated with audiometric HI (low physical activity, poor physical functioning, and hospitalization).

RESULTS

In adjusted models, we found significant associations of audiometric HI with both subjective and objective outcomes (e.g., dichotomous HI with self-reported difficulty in activities of daily living [ADLs], odds ratio [OR] = 1.47, 95% confidence interval [CI] [1.05, 2.06], and low accelerometer-measured physical activity, OR = 2.19, 95% CI [1.11, 4.34]). In contrast, self-reported HI was only associated with subjective outcomes and not with objective outcomes (e.g., dichotomous HI with difficulty in ADLs, OR = 1.63, 95% CI [1.12, 2.38], and low accelerometer-measured physical activity, OR = 0.95, 95% CI [0.66, 1.35]).

DISCUSSION

Results using self-reported hearing should not be considered representative of results using audiometry and may provide distinct aspects of HI in older adults.

The Effect of Age on Listening Effort

PURPOSE

The objective of this study was to investigate the effect of age on listening effort.

METHOD

A dual-task paradigm was used to evaluate listening effort in different conditions of background noise. Sixty adults ranging in age from 20 to 77 years were included. A primary speech-recognition task and a secondary memory task were performed both separately and simultaneously. Multiple regression analyses were used to evaluate how age and hearing thresholds affect speech recognition and listening effort scores.

RESULTS

Results of the multiple regression analyses showed that age is a significant determinant of listening effort, whereby listening effort increases with increasing age even when age-related variance in speech recognition is partialled out. On the basis of the regression equations and the median score for listening effort, it was found that listening effort started to increase in the fourth decade of life.

CONCLUSIONS

This study was a first exploration of listening effort from young to older adults and showed that, independent of hearing sensitivity, listening effort increases with age. To be more specific, there is a need to further investigate the cognitive functions important for speech communication while exploring their possible relationship with listening effort.

Can a Remotely Delivered Auditory Training Program Improve Speech-in-Noise Understanding?

PURPOSE

The aims of this study were to determine if a remotely delivered, Internet-based auditory training (AT) program improved speech-in-noise understanding and if the number of hours spent engaged in the program influenced postintervention speech-in-noise understanding.

METHOD

Twenty-nine first-time hearing aid users were randomized into an AT group (hearing aids + 3 week remotely delivered, Internet-based auditory training program) or a control group (hearing aids alone). The Hearing in Noise Test (Nilsson, Soli, & Sullivan, 1994) and the Words-in-Noise test (Wilson, 2003) were administered to both groups at baseline + 1 week and immediately at the completion of the 3 weeks of auditory training.

RESULTS

Speech-in-noise understanding improved for both groups at the completion of the study; however, there was not a statistically significant difference in postintervention improvement between the AT and control groups. Although the number of hours the participants engaged in the AT program was far fewer than prescribed, time on task influenced the postintervention Words-in-Noise but not Hearing in Noise Test scores.

CONCLUSION

Although remotely delivered, Internet-based AT programs represent an attractive alternative to resource-intensive, clinic-based interventions, their demonstrated efficacy continues to remain a challenge due in part to issues associated with compliance.

Effects of hearing loss on heart rate variability and skin conductance measured during sentence recognition in noise

OBJECTIVE

The purpose of the study was to determine the effects of hearing loss and noise on (1) two autonomic nervous system measures associated with stress (skin conductance and heart rate variability) and on (2) subjective ratings of workload/stress. The authors hypothesized that hearing loss would increase psychophysiological and subjective reactivity to noise during speech recognition tasks. Both psychophysiological and subjective indicators of workload/stress were expected to increase with a reduction in signal-to-noise ratio.

DESIGN

Sentence recognition in the presence of babble noise was assessed in 15 adults with clinically normal hearing and 18 adults with sensorineural hearing loss. Mean sentence recognition was equalized for the two groups using an adaptive procedure to estimate 80% recognition of words in sentences. Sentences were then presented in quiet and at four fixed signal-to-noise ratios: -6, -3, 0, and +3 dB relative to the individually determined signal-to-noise thresholds. Electrocardiography and skin conductance recordings were obtained during each listening condition. The high-frequency spectral component of heart rate variability was extracted from the electrocardiographic recordings as a measure of parasympathetic nervous system activity. Subjective ratings of effort, mental demand, stress, and perceived performance were obtained after each listening condition using the National Aeronautics and Space Administration Task Load Index.

RESULTS

Recognition scores referenced to the adaptive threshold were similar for the two groups. Participants with hearing loss showed a decrease in high-frequency heart rate variability at lower signal-to-noise ratios, whereas those with normal hearing did not. Skin conductance levels were not sensitive to changes in signal-to-noise ratio. However, overall skin conductance reactivity to noise (relative to quiet) was higher for those with hearing loss than for those with normal hearing. In contrast to the psychophysiological findings, there were no significant differences between subjective ratings for the two groups.

CONCLUSIONS

Listeners with hearing loss show greater autonomic nervous system reactivity to babble noise during speech recognition than do listeners with normal hearing, when recognition performance is equal. The findings are consistent with the conclusion that listeners with hearing loss experience increased effort and/or stress during speech recognition in noise.

Evaluation of Speech Perception via the Use of Hearing Loops and Telecoils

A cross-sectional, experimental, and randomized repeated-measures design study was used to examine the objective and subjective value of telecoil and hearing loop systems. Word recognition and speech perception were tested in 12 older adult hearing aid users using the telecoil and microphone inputs in quiet and noise conditions. Participants were asked to subjectively rate cognitive listening effort and self-confidence for each condition. Significant improvement in speech perception with the telecoil over microphone input in both quiet and noise was found along with significantly less reported cognitive listening effort and high self-confidence. The use of telecoils with hearing aids should be recommended for older adults with hearing loss.

Peripheral Hearing and Cognition: Evidence From the Staying Keen in Later Life (SKILL) Study

OBJECTIVES

Research has increasingly suggested a consistent relationship between peripheral hearing and selected measures of cognition in older adults. However, other studies yield conflicting findings. The primary purpose of the present study was to further elucidate the relationship between peripheral hearing and three domains of cognition and one measure of global cognitive status. It was hypothesized that peripheral hearing loss would be significantly associated with poorer performance across measures of cognition, even after adjusting for documented risk factors. No study to date has examined the relationship between peripheral hearing and such an extensive array of cognitive measures.

DESIGN

Eight hundred ninety-four older adult participants from the Staying Keen in Later Life study cohort were eligible, agreed to participate, and completed the baseline evaluation. Inclusion criteria were minimal to include a sample of older adults with a wide range of sensory and cognitive abilities. Multiple linear regression analyses were conducted to evaluate the extent to which peripheral hearing predicted performance on a global measure of cognitive status, as well as multiple cognitive measures in the domains of speed of processing (Digit Symbol Substitution and Copy, Trail Making Test Part A, Letter and Pattern Comparison, and Useful Field of View), executive function (Trail Making Test Part B and Stroop Color-Word Interference Task), and memory (Digit Span, Spatial Span, and Hopkins Verbal Learning Test).

RESULTS

Peripheral hearing, measured as the three-frequency pure-tone average (PTA) in the better ear, accounted for a significant, but minimal, amount of the variance in measures of speed of processing, executive function, and memory, as well as global cognitive status. Alternative measures of hearing (i.e., three-frequency PTAs in the right and left ears and a bilateral, six-frequency PTA [three frequencies per ear]) yielded similar findings across measures of cognition and did not alter the study outcomes in any meaningful way.

CONCLUSIONS

Consistent with literature suggesting a significant relationship between peripheral hearing and cognition, and in agreement with our hypothesis, peripheral hearing was significantly related to 10 of 11 measures of cognition that assessed processing speed, executive function, or memory, as well as global cognitive status. Although evidence, including the present results, suggests a relationship between peripheral hearing and cognition, little is known about the underlying mechanisms. Examination of these mechanisms is a critical need to direct appropriate treatment.

Relatively effortless listening promotes understanding and recall of medical instructions in older adults

Communication success under adverse conditions requires efficient and effective recruitment of both bottom-up (sensori-perceptual) and top-down (cognitive-linguistic) resources to decode the intended auditory-verbal message. Employing these limited capacity resources has been shown to vary across the lifespan, with evidence indicating that younger adults out-perform older adults for both comprehension and memory of the message. This study examined how sources of interference arising from the speaker (message spoken with conversational vs. clear speech technique), the listener (hearing-listening and cognitive-linguistic factors), and the environment (in competing speech babble noise vs. quiet) interact and influence learning and memory performance using more ecologically valid methods than has been done previously. The results suggest that when older adults listened to complex medical prescription instructions with “clear speech,” (presented at audible levels through insertion earphones) their learning efficiency, immediate, and delayed memory performance improved relative to their performance when they listened with a normal conversational speech rate (presented at audible levels in sound field). This better learning and memory performance for clear speech listening was maintained even in the presence of speech babble noise. The finding that there was the largest learning-practice effect on 2nd trial performance in the conversational speech when the clear speech listening condition was first is suggestive of greater experience-dependent perceptual learning or adaptation to the speaker's speech and voice pattern in clear speech. This suggests that experience-dependent perceptual learning plays a role in facilitating the language processing and comprehension of a message and subsequent memory encoding.

The benefit of amplification on auditory working memory function in middle-aged and young-older hearing impaired adults

Untreated hearing loss can interfere with an individual’s cognitive abilities and intellectual function. Specifically, hearing loss has been shown to negatively impact working memory function, which is important for speech understanding, especially in difficult or noisy listening conditions. The purpose of the present study was to assess the effect of hearing aid use on auditory working memory function in middle-aged and young-older adults with mild to moderate sensorineural hearing loss. Participants completed two objective measures of auditory working memory in aided and unaided listening conditions. An aged matched control group followed the same experimental protocol except they were not fit with hearing aids. All participants’ aided scores on the auditory working memory tests were significantly improved while wearing hearing aids. Thus, hearing aids worn during the early stages of an age-related hearing loss can improve a person’s performance on auditory working memory tests.

Rapid adaptation to time-compressed speech in young and older adults

BACKGROUND

The ability of human listeners to comprehend rapid speech improves quickly with experience, a process known as adaptation. Whether inefficient adaptation to rapid speech partially accounts for the marked difficulties of older listeners with rapid speech is not clear.

METHODS

Two conditions of adaptation to time-compressed speech were used. A baseline condition intended to test the hypothesis that adaptation is different in older and younger listeners, and an interference condition in which sentences compressed to two different rates were interleaved. Identification accuracy was compared between two time points (before and after adaptation) and between older and younger listeners.

RESULTS

The effects of adaptation did not differ between younger and older listeners in either adaptation condition.

CONCLUSIONS

It seems that once initial performance differences are taken into account, rapid adaptation to time-compressed speech is as effective and as immune to interference by competing speech rates in younger and older adults.

Hearing impairment and cognitive decline: a pilot study conducted within the atherosclerosis risk in communities neurocognitive study

Hearing impairment (HI) is prevalent, is modifiable, and has been associated with cognitive decline. We tested the hypothesis that audiometric HI measured in 2013 is associated with poorer cognitive function in 253 men and women from Washington County, Maryland (mean age = 76.9 years) in a pilot study carried out within the Atherosclerosis Risk in Communities Neurocognitive Study. Three cognitive tests were administered in 1990-1992, 1996-1998, and 2013, and a full neuropsychological battery was administered in 2013. Multivariable-adjusted differences in standardized cognitive scores (cross-sectional analysis) and trajectories of 20-year change (longitudinal analysis) were modeled using linear regression and generalized estimating equations, respectively. Hearing thresholds for pure tone frequencies of 0.5-4 kHz were averaged to obtain a pure tone average in the better-hearing ear. Hearing was categorized as follows: ≤25 dB, no HI; 26-40 dB, mild HI; and >40 dB, moderate/severe HI. Comparing participants with moderate/severe HI to participants with no HI, 20-year rates of decline in memory and global function differed by -0.47 standard deviations (P = 0.02) and -0.29 standard deviations (P = 0.02), respectively. Estimated declines were greatest in participants who did not wear a hearing aid. These findings add to the limited literature on cognitive impairments associated with HI, and they support future research on whether HI treatment may reduce risk of cognitive decline.

Acoustic Detail Guides Attention Allocation in a Selective Listening Task

The flexible allocation of attention enables us to perceive and behave successfully despite irrelevant distractors. How do acoustic challenges influence this allocation of attention, and to what extent is this ability preserved in normally aging listeners? Younger and healthy older participants performed a masked auditory number comparison while EEG was recorded. To vary selective attention demands, we manipulated perceptual separability of spoken digits from a masking talker by varying acoustic detail (temporal fine structure). Listening conditions were adjusted individually to equalize stimulus audibility as well as the overall level of performance across participants. Accuracy increased, and response times decreased with more acoustic detail. The decrease in response times with more acoustic detail was stronger in the group of older participants. The onset of the distracting speech masker triggered a prominent contingent negative variation (CNV) in the EEG. Notably, CNV magnitude decreased parametrically with increasing acoustic detail in both age groups. Within identical levels of acoustic detail, larger CNV magnitude was associated with improved accuracy. Across age groups, neuropsychological markers further linked early CNV magnitude directly to individual attentional capacity. Results demonstrate for the first time that, in a demanding listening task, instantaneous acoustic conditions guide the allocation of attention. Second, such basic neural mechanisms of preparatory attention allocation seem preserved in healthy aging, despite impending sensory decline.

How hearing impairment affects sentence comprehension: using eye fixations to investigate the duration of speech processing

The main objective of this study was to investigate the extent to which hearing impairment influences the duration of sentence processing. An eye-tracking paradigm is introduced that provides an online measure of how hearing impairment prolongs processing of linguistically complex sentences; this measure uses eye fixations recorded while the participant listens to a sentence. Eye fixations toward a target picture (which matches the aurally presented sentence) were measured in the presence of a competitor picture. Based on the recorded eye fixations, the single target detection amplitude, which reflects the tendency of the participant to fixate the target picture, was used as a metric to estimate the duration of sentence processing. The single target detection amplitude was calculated for sentence structures with different levels of linguistic complexity and for different listening conditions: in quiet and in two different noise conditions. Participants with hearing impairment spent more time processing sentences, even at high levels of speech intelligibility. In addition, the relationship between the proposed online measure and listener-specific factors, such as hearing aid use and cognitive abilities, was investigated. Longer processing durations were measured for participants with hearing impairment who were not accustomed to using a hearing aid. Moreover, significant correlations were found between sentence processing duration and individual cognitive abilities (such as working memory capacity or susceptibility to interference). These findings are discussed with respect to audiological applications.

Costs of switching auditory spatial attention in following conversational turn-taking

Following a multi-talker conversation relies on the ability to rapidly and efficiently shift the focus of spatial attention from one talker to another. The current study investigated the listening costs associated with shifts in spatial attention during conversational turn-taking in 16 normally-hearing listeners using a novel sentence recall task. Three pairs of syntactically fixed but semantically unpredictable matrix sentences, recorded from a single male talker, were presented concurrently through an array of three loudspeakers (directly ahead and +/−30° azimuth). Subjects attended to one spatial location, cued by a tone, and followed the target conversation from one sentence to the next using the call-sign at the beginning of each sentence. Subjects were required to report the last three words of each sentence (speech recall task) or answer multiple choice questions related to the target material (speech comprehension task). The reading span test, attention network test, and trail making test were also administered to assess working memory, attentional control, and executive function. There was a 10.7 ± 1.3% decrease in word recall, a pronounced primacy effect, and a rise in masker confusion errors and word omissions when the target switched location between sentences. Switching costs were independent of the location, direction, and angular size of the spatial shift but did appear to be load dependent and only significant for complex questions requiring multiple cognitive operations. Reading span scores were positively correlated with total words recalled, and negatively correlated with switching costs and word omissions. Task switching speed (Trail-B time) was also significantly correlated with recall accuracy. Overall, this study highlights (i) the listening costs associated with shifts in spatial attention and (ii) the important role of working memory in maintaining goal relevant information and extracting meaning from dynamic multi-talker conversations.

Spatial release of cognitive load measured in a dual-task paradigm in normal-hearing and hearing-impaired listeners

This study investigated whether spatial separation between talkers helps reduce cognitive processing load, and how hearing impairment interacts with the cognitive load of individuals listening in multi-talker environments. A dual-task paradigm was used in which performance on a secondary task (visual tracking) served as a measure of the cognitive load imposed by a speech recognition task. Visual tracking performance was measured under four conditions in which the target and the interferers were distinguished by (1) gender and spatial location, (2) gender only, (3) spatial location only, and (4) neither gender nor spatial location. Results showed that when gender cues were available, a 15° spatial separation between talkers reduced the cognitive load of listening even though it did not provide further improvement in speech recognition (Experiment I). Compared to normal-hearing listeners, large individual variability in spatial release of cognitive load was observed among hearing-impaired listeners. Cognitive load was lower when talkers were spatially separated by 60° than when talkers were of different genders, even though speech recognition was comparable in these two conditions (Experiment II). These results suggest that a measure of cognitive load might provide valuable insight into the benefit of spatial cues in multi-talker environments.

Cortical activity predicts which older adults recognize speech in noise and when

Speech recognition in noise can be challenging for older adults and elicits elevated activity throughout a cingulo-opercular network that is hypothesized to monitor and modify behaviors to optimize performance. A word recognition in noise experiment was used to test the hypothesis that cingulo-opercular engagement provides performance benefit for older adults. Healthy older adults (N = 31; 50-81 years of age; mean pure tone thresholds <32 dB HL from 0.25 to 8 kHz, best ear; species: human) performed word recognition in multitalker babble at 2 signal-to-noise ratios (SNR = +3 or +10 dB) during a sparse sampling fMRI experiment. Elevated cingulo-opercular activity was associated with an increased likelihood of correct recognition on the following trial independently of SNR and performance on the preceding trial. The cingulo-opercular effect increased for participants with the best overall performance. These effects were lower for older adults compared with a younger, normal-hearing adult sample (N = 18). Visual cortex activity also predicted trial-level recognition for the older adults, which resulted from discrete decreases in activity before errors and occurred for the oldest adults with the poorest recognition. Participants demonstrating larger visual cortex effects also had reduced fractional anisotropy in an anterior portion of the left inferior frontal-occipital fasciculus, which projects between frontal and occipital regions where activity predicted word recognition. Together, the results indicate that older adults experience performance benefit from elevated cingulo-opercular activity, but not to the same extent as younger adults, and that declines in attentional control can limit word recognition.

Aided and unaided speech perception by older hearing impaired listeners

The most common complaint of older hearing impaired (OHI) listeners is difficulty understanding speech in the presence of noise. However, tests of consonant-identification and sentence reception threshold (SeRT) provide different perspectives on the magnitude of impairment. Here we quantified speech perception difficulties in 24 OHI listeners in unaided and aided conditions by analyzing (1) consonant-identification thresholds and consonant confusions for 20 onset and 20 coda consonants in consonant-vowel-consonant (CVC) syllables presented at consonant-specific signal-to-noise (SNR) levels, and (2) SeRTs obtained with the Quick Speech in Noise Test (QSIN) and the Hearing in Noise Test (HINT). Compared to older normal hearing (ONH) listeners, nearly all unaided OHI listeners showed abnormal consonant-identification thresholds, abnormal consonant confusions, and reduced psychometric function slopes. Average elevations in consonant-identification thresholds exceeded 35 dB, correlated strongly with impairments in mid-frequency hearing, and were greater for hard-to-identify consonants. Advanced digital hearing aids (HAs) improved average consonant-identification thresholds by more than 17 dB, with significant HA benefit seen in 83% of OHI listeners. HAs partially normalized consonant-identification thresholds, reduced abnormal consonant confusions, and increased the slope of psychometric functions. Unaided OHI listeners showed much smaller elevations in SeRTs (mean 6.9 dB) than in consonant-identification thresholds and SeRTs in unaided listening conditions correlated strongly (r = 0.91) with identification thresholds of easily identified consonants. HAs produced minimal SeRT benefit (2.0 dB), with only 38% of OHI listeners showing significant improvement. HA benefit on SeRTs was accurately predicted (r = 0.86) by HA benefit on easily identified consonants. Consonant-identification tests can accurately predict sentence processing deficits and HA benefit in OHI listeners.

Long-term use of cochlear implants in older adults: results from a large consecutive case series

OBJECTIVE

To investigate rates of long-term use of cochlear implants in a large, consecutive case series of older adults (≥60 yr).

STUDY DESIGN

Consecutive case series.

SETTING

Tertiary referral center.

PATIENTS

Approximately 447 individuals 60 years or older who received their first CI from 1999 to 2011. We successfully contacted 397 individuals (89%) to ascertain data on the individual's daily CI use averaged over the past 4 weeks.

INTERVENTION

Cochlear implantation.

MAIN OUTCOME MEASURE

Regular CI use was defined as 8 hours or greater of use per day. We investigated the time from implantation to the date when an individual reported discontinuing regular CI use.

RESULTS

The overall rate of regular CI use at 13.5 years of follow-up was 82.6% (95% CI, 72.5%-89.3%). Individuals who received a CI at 60 to 74 years had significantly higher rates of regular CI use at 13.5 years of follow-up (91.1% [95% CI, 83.2%-95.4%], n = 251) than individuals who received a CI at 75 years or older (55.7% [95% CI, 24.9%-78.1%], n = 146). The rate of discontinuing regular CI use (<8 hr/d) increased on average by 7.8% (95% CI, 3.0%-12.8%) per year of age at implantation.

CONCLUSION

Rates of long-term CI use in older adults at more than 10 years of follow-up exceed 80%. The rate of discontinuing regular CI use was strongly associated with older age at implantation. These results suggest that early implantation of older adults, once critically low levels of speech recognition are present, is associated with greater usage of the device.

Relationship of hearing loss and dementia: a prospective, population-based study

OBJECTIVE

To determine whether baseline hearing loss increases cognitive decline and risk for all-cause dementia in a population of elderly individuals.

STUDY DESIGN

Longitudinal cohort study.

SETTING

Community-based, outpatient.

PATIENTS

Men and women aged 65 years or older without dementia at baseline.

INTERVENTION(S)

All subjects completed the Modified Mini-Mental Status Exam (3MS-R) at baseline and over 3 triennial follow-up visits. Hearing loss (HL) at baseline was based on observation of hearing difficulties during testing or interview. Incident dementia was determined by clinical assessment and expert consensus.

MAIN OUTCOME MEASURE(S)

Dementia and 3MS-R score.

RESULTS

At baseline, 4,463 subjects were without dementia, 836 of whom had HL. Of those with HL, 16.3% developed dementia, compared with 12.1% of those without HL (p < 0.001). Mean time to dementia was 10.3 years in the HL group versus 11.9 years for non-HL (log rank test p < 0.001). In Cox regression analyses controlling for sex, presence of APOE- [Latin Small Letter Open E]4 allele, education, and baseline age, and cardiovascular risk factors, HL was an independent predictor of developing dementia (hazard ratio = 1.27, p = 0.026 [95% CI, 1.03-1.56]). Linear mixed models controlling for similar covariates showed HL was associated with faster decline on the 3MS-R, at a rate of 0.26 points/year worse than those without HL.

CONCLUSION

Elderly individuals with HL have an increased rate of developing dementia and more rapid decline on 3MS-R scores than their nonhearing impaired counterparts. These findings suggest that hearing impairment may be a marker for cognitive dysfunction in adults age 65 years and older.

At the interface of sensory and motor dysfunctions and Alzheimer's disease

Recent evidence indicates that sensory and motor changes may precede the cognitive symptoms of Alzheimer's disease (AD) by several years and may signify increased risk of developing AD. Traditionally, sensory and motor dysfunctions in aging and AD have been studied separately. To ascertain the evidence supporting the relationship between age-related changes in sensory and motor systems and the development of AD and to facilitate communication between several disciplines, the National Institute on Aging held an exploratory workshop titled "Sensory and Motor Dysfunctions in Aging and AD." The scientific sessions of the workshop focused on age-related and neuropathologic changes in the olfactory, visual, auditory, and motor systems, followed by extensive discussion and hypothesis generation related to the possible links among sensory, cognitive, and motor domains in aging and AD. Based on the data presented and discussed at this workshop, it is clear that sensory and motor regions of the central nervous system are affected by AD pathology and that interventions targeting amelioration of sensory-motor deficits in AD may enhance patient function as AD progresses.

The effect of functional hearing loss and age on long- and short-term visuospatial memory: evidence from the UK biobank resource

The UK Biobank offers cross-sectional epidemiological data collected on >500,000 individuals in the UK between 40 and 70 years of age. Using the UK Biobank data, the aim of this study was to investigate the effects of functional hearing loss and hearing aid usage on visuospatial memory function. This selection of variables resulted in a sub-sample of 138,098 participants after discarding extreme values. A digit triplets functional hearing test was used to divide the participants into three groups: poor, insufficient and normal hearers. We found negative relationships between functional hearing loss and both visuospatial working memory (i.e., a card pair matching task) and visuospatial, episodic long-term memory (i.e., a prospective memory task), with the strongest association for episodic long-term memory. The use of hearing aids showed a small positive effect for working memory performance for the poor hearers, but did not have any influence on episodic long-term memory. Age also showed strong main effects for both memory tasks and interacted with gender and education for the long-term memory task. Broader theoretical implications based on a memory systems approach will be discussed and compared to theoretical alternatives.

Association of hearing impairment with declines in physical functioning and the risk of disability in older adults

BACKGROUND

Identifying factors associated with functional declines in older adults is important given the aging of the population. We investigated if hearing impairment is independently associated with objectively measured declines in physical functioning in a community-based sample of older adults.

METHODS

Prospective observational study of 2,190 individuals from the Health, Aging, and Body Composition study. Participants were followed annually for up to 11 visits. Hearing was measured with pure-tone audiometry. Physical functioning and gait speed were measured with the Short Physical Performance Battery (SPPB). Incident disability and requirement for nursing care were assessed semiannually through self-report.

RESULTS

In a mixed-effects model, greater hearing impairment was associated with poorer physical functioning. At both Visit 1 and Visit 11, SPPB scores were lower in individuals with mild (10.14 [95% CI 10.04-10.25], p < .01; 7.35 [95% CI 7.12-7.58], p < .05) and moderate or greater hearing impairment (10.04 [95% CI 9.90-10.19], p < .01; 7.00 [95% CI 6.69-7.32], p < .01) than scores in normal hearing individuals (10.36 [95% CI 10.26-10.46]; 7.71 [95% CI 7.49-7.92]). We observed that women with moderate or greater hearing impairment had a 31% increased risk of incident disability (Hazard ratio [HR] =1.31 [95% CI 1.08-1.60], p < .01) and a 31% increased risk of incident nursing care requirement (HR = 1.31 [95% CI 1.05-1.62], p = .02) compared to women with normal hearing.

CONCLUSIONS

Hearing impairment is independently associated with poorer objective physical functioning in older adults, and a 31% increased risk for incident disability and need for nursing care in women.

Effects of masker type, sentence context, and listener age on speech recognition performance in 1-back listening tasks

Studies have shown that older listeners with normal hearing have greater difficulty understanding speech in noisy environments than younger listeners even during simple assessments where listeners respond to auditory stimuli immediately after presentation. Older listeners may have increased difficulty understanding speech in challenging listening situations that require the recall of prior sentences during the presentation of new auditory stimuli. This study compared the performance of older and younger normal-hearing listeners in 0-back trials, which required listeners to respond to the most recent sentence, and 1-back trials, which required the recall of the sentence preceding the most recent. Speech stimuli were high-context and anomalous sentences with four types of maskers. The results show that older listeners have greater difficulty in the 1-back task than younger listeners with all masker types, even when SNR was adjusted to produce 80% correct performance in the 0-back task for both groups. The differences between the groups in the 1-back task may be explained by differences in working memory for the noise and spatially separated speech maskers but not in the conditions with co-located speech maskers, suggesting that older listeners have increased difficulty in memory-intensive speech perception tasks involving high levels of informational masking.

Assessment of Adult Age differences in Task Engagement: The Utility of Systolic Blood Pressure

The constructs of effort and engagement are central to many theoretical frameworks associated with the study of aging. Age differences in the effort associated with effortful cognitive operations have been hypothesized to account for aging effects in ability, and shifting goals and motivation have been hypothesized to be associated with differential levels of engagement across situations in younger and older adults. Unfortunately, the assessment of effort and engagement-constructs that we view as relatively synonymous-has suffered in the field of aging due to the lack of well-validated measures. We suggest that systolic blood pressure might provide an easy and valid means for examining age differences in mental effort, and present evidence in support of its usage. Existing findings clearly support its potential utility, but further empirical and theoretical work is necessary.

Patient-reported cognitive functioning and daily functioning in chronic dialysis patients

Subjective cognitive impairment negatively affects daily functioning, health-related quality of life, and health care consumption, and is predictive of future cognitive decline in many patient populations. However, no subjective measures of multidimensional cognitive functioning have been evaluated for dialysis patients. Our purposes were to examine (1) the association between patient-reported (subjective) cognitive functioning and objective cognitive functioning and (2) the relationships between subjective and objective cognitive functioning and everyday functioning of dialysis patients. We used baseline data from an ongoing longitudinal observational study of trajectories in dialysis patients' multidimensional quality of life. One hundred thirty-five patients completed a telephone-based neuropsychological battery (Brief Test of Adult Cognition by Telephone, a measure of objective cognitive functioning), a measure of subjective cognitive functioning (Patient's Assessment of Own Functioning Inventory), and measures of everyday functioning (Activities of Daily Living [ADL] and Instrumental Activities of Daily Living [IADL] scales). After controlling for age and education, there was a modest correlation (r = 0.33, P > 0.001) between subjective and objective cognitive functioning. Multivariate logistic regression models showed subjective, but not objective, cognitive functioning was a significant predictor of both ADLs and IADLs. The findings suggest the potential clinical value of subjective measures of cognitive functioning, not to replace objective measures or diagnostic tests, but rather to optimize the meaningfulness of clinical assessment and management.

Association between hearing impairment and lower levels of physical activity in older adults

OBJECTIVES

To determine whether hearing impairment, highly prevalent in older adults, is associated with activity levels.

DESIGN

Cross-sectional.

SETTING

National Health and Nutritional Examination Survey (2005-06).

PARTICIPANTS

Individuals aged 70 and older who completed audiometric testing and whose physical activity was assessed subjectively using questionnaires and objectively using body-worn accelerometers (N=706).

MEASUREMENTS

Hearing impairment was defined according to the speech-frequency (0.5-4 kHz) pure-tone average in the better-hearing ear (normal <25.0 dB, mild 25.0-39.9 dB, moderate or greater ≥40 dB). Main outcome measures were self-reported leisure time physical activity and accelerometer-measured physical activity. Both were quantified using minutes of moderate-intensity physical activity and categorized as inactive, insufficiently active, or sufficiently active. Ordinal logistic regression analyses were conducted and adjusted for demographic and cardiovascular risk factors.

RESULTS

Individuals with moderate or greater hearing impairment had greater odds than those with normal hearing of being in a lower category of physical activity as measured according to self-report (OR=1.59, 95% CI=1.11-2.28) and accelerometry (OR=1.70, 95% CI=0.99-2.91). Mild hearing impairment was not associated with level of physical activity.

CONCLUSION

Moderate or greater hearing impairment in older adults is associated with lower levels of physical activity independent of demographic and cardiovascular risk factors. Future research is needed to investigate the basis of this association and whether hearing rehabilitative interventions could affect physical activity in older adults.

Selective Engagement of Cognitive Resources: Motivational Influences on Older Adults' Cognitive Functioning

In this article, I present a framework for understanding the impact of aging-related declines in cognitive resources on functioning. I make the assumption that aging is associated with an increase in the costs of cognitive engagement, as reflected in both the effort required to achieve a specific level of task performance and the associated depletion or fatigue effects. I further argue that these costs result in older adults being increasingly selective in the engagement of cognitive resources in response to these declines. This selectivity is reflected in (a) a reduction in the intrinsic motivation to engage in cognitively demanding activities, which, in part, accounts for general reductions in engagement in such activities, and (b) greater sensitivity to the self-related implications of a given task. Both processes are adaptive if viewed in terms of resource conservation, but the former may also be maladaptive to the extent that it results in older adults restricting participation in cognitively demanding activities that could ultimately benefit cognitive health. I review supportive research and make the general case for the importance of considering motivational factors in understanding aging effects on cognitive functioning.

Speech-perception training for older adults with hearing loss impacts word recognition and effort

The current pupillometry study examined the impact of speech-perception training on word recognition and cognitive effort in older adults with hearing loss. Trainees identified more words at the follow-up than at the baseline session. Training also resulted in an overall larger and faster peaking pupillary response, even when controlling for performance and reaction time. Perceptual and cognitive capacities affected the peak amplitude of the pupil response across participants but did not diminish the impact of training on the other pupil metrics. Thus, we demonstrated that pupillometry can be used to characterize training-related and individual differences in effort during a challenging listening task. Importantly, the results indicate that speech-perception training not only affects overall word recognition, but also a physiological metric of cognitive effort, which has the potential to be a biomarker of hearing loss intervention outcome.

Monitoring the capacity of working memory: executive control and effects of listening effort

In two experiments, we used an interruption-and-recall (IAR) task to explore listeners' ability to monitor the capacity of working memory as new information arrived in real time. In this task, listeners heard recorded word lists with instructions to interrupt the input at the maximum point that would still allow for perfect recall. Experiment 1 demonstrated that the most commonly selected segment size closely matched participants' memory span, as measured in a baseline span test. Experiment 2 showed that reducing the sound level of presented word lists to a suprathreshold but effortful listening level disrupted the accuracy of matching selected segment sizes with participants' memory spans. The results are discussed in terms of whether online capacity monitoring may be subsumed under other, already enumerated working memory executive functions (inhibition, set shifting, and memory updating).

Acoustic masking disrupts time-dependent mechanisms of memory encoding in word-list recall

Recall of recently heard words is affected by the clarity of presentation: Even if all words are presented with sufficient clarity for successful recognition, those that are more difficult to hear are less likely to be recalled. Such a result demonstrates that memory processing depends on more than whether a word is simply "recognized" versus "not recognized." More surprising is that, when a single item in a list of spoken words is acoustically masked, prior words that were heard with full clarity are also less likely to be recalled. To account for such a phenomenon, we developed the linking-by-active-maintenance model (LAMM). This computational model of perception and encoding predicts that these effects will be time dependent. Here we challenged our model by investigating whether and how the impact of acoustic masking on memory depends on presentation rate. We found that a slower presentation rate causes a more disruptive impact of stimulus degradation on prior, clearly heard words than does a fast rate. These results are unexpected according to prior theories of effortful listening, but we demonstrated that they can be accounted for by LAMM.

Association between hearing impairment and self-reported difficulty in physical functioning

OBJECTIVES

To determine whether hearing impairment, defined by using objective audiometry, is associated with multiple categories of self-reported physical functioning in a cross-sectional, nationally representative sample of older adults.

DESIGN

Multivariate secondary analysis of cross-sectional data.

SETTING

The 2005-06 and 2009-10 cycles of the National Health and Nutrition Examination Survey.

PARTICIPANTS

Adults aged 70 and older who completed audiometric testing (N = 1,669).

MEASUREMENTS

Hearing was measured using pure-tone audiometry. Physical functioning was assessed using a structured interview.

RESULTS

In a model adjusted for age and demographic and cardiovascular risk factors, greater hearing impairment (per 25 dB hearing level (HL)) was associated with greater odds of physical disability in activities of daily living (odds ratio (OR) = 1.4, 95% confidence interval (CI) = 1.1-1.9), instrumental activities of daily living (OR = 1.6, 95% CI = 1.2-2.2), leisure and social activities (OR = 1.5, 95% CI = 1.1-2.0), lower extremity mobility (OR = 1.4, 95% CI = 1.1-1.7), general physical activities (OR = 1.3, 95% CI = 1.1-1.6), work limitation (OR = 1.4, 95% CI = 1.0-1.9), walking limitation (OR = 1.6, 95% CI = 1.3-2.0), and limitation due to memory or confusion (OR = 1.4, 95% CI = 1.1-1.8). Hearing impairment was not associated with limitations in amount or type of work done (OR = 1.2, 95% CI = 1.0-1.6).

CONCLUSION

Hearing impairment in older adults is independently associated with greater disability and limitations in multiple self-reported categories of physical functioning.

Saying it with a natural child's voice! When affective auditory manipulations increase working memory in aging

OBJECTIVES

Working memory functions and their relations with affective auditory factors, have not been extensively investigated in aging yet.

METHOD

In this study, younger and older participants completed a classical working memory test (a running working memory task) pronounced by three different voices. In particular, in Experiment 1 the natural voices of a 3-year-old child, a 26-year-old young adult and an 86-year-old older adult were used for task presentation. In Experiment 2 stimuli were morphed in order to better control for sound properties across the three voices.

RESULTS

Results showed that working memory increased for older adults compared to younger adults when the task was presented with natural voices and especially so when the task was presented in a child's voice. However, the child-voice effect disappeared with morphed voices.

CONCLUSION

Data confirm the importance of studying the relationship between auditory features and emotional variations as a possible practical means of reducing typical age-related working memory deficits.

Association of hearing impairment with brain volume changes in older adults

Hearing impairment in older adults is independently associated in longitudinal studies with accelerated cognitive decline and incident dementia, and in cross-sectional studies, with reduced volumes in the auditory cortex. Whether peripheral hearing impairment is associated with accelerated rates of brain atrophy is unclear. We analyzed brain volume measurements from magnetic resonance brain scans of individuals with normal hearing versus hearing impairment (speech-frequency pure tone average>25 dB) followed in the neuroimaging substudy of the Baltimore Longitudinal Study of Aging for a mean of 6.4 years after the baseline scan (n=126, age 56-86 years). Brain volume measurements were performed with semi-automated region-of-interest (ROI) algorithms, and brain volume trajectories were analyzed with mixed-effect regression models adjusted for demographic and cardiovascular factors. We found that individuals with hearing impairment (n=51) compared to those with normal hearing (n=75) had accelerated volume declines in whole brain and regional volumes in the right temporal lobe (superior, middle, and inferior temporal gyri, parahippocampus, p<.05). These results were robust to adjustment for multiple confounders and were consistent with voxel-based analyses, which also implicated right greater than left temporal regions. These findings demonstrate that peripheral hearing impairment is independently associated with accelerated brain atrophy in whole brain and regional volumes concentrated in the right temporal lobe. Further studies investigating the mechanistic basis of the observed associations are needed.