Simultaneous EEG and MEG recordings reveal vocal pitch elicited cortical gamma oscillations in young and older adults.

The frequency-following response with origin in the auditory brainstem represents the pitch contour of voice and can be recorded with electrodes from the scalp. MEG studies also revealed a cortical contribution to the high gamma oscillations at the fundamental frequency (f0) of a vowel stimulus. Therefore, studying the cortical component of the frequency-following response could provide insights into how pitch information is encoded at the cortical level. Comparing how aging affects the different responses may help to uncover the neural mechanisms underlying speech understanding deficits in older age. We simultaneously recorded EEG and MEG responses to the syllable /ba/. MEG beamformer analysis localized sources in bilateral auditory cortices and the midbrain. Time-frequency analysis showed a faithful representation of the pitch contour between 106 Hz and 138 Hz in the cortical activity. A cross-correlation revealed a latency of 20 ms. Furthermore, stimulus onsets elicited cortical 40-Hz responses. Both the 40-Hz and the f0 response amplitudes increased in older age and were larger in the right hemisphere. The effects of aging and laterality of the f0 response were evident in the MEG only, suggesting that both effects were characteristics of the cortical response. After comparing f0 and N1 responses in EEG and MEG, we estimated that approximately one-third of the scalp-recorded f0 response could be cortical in origin. We attributed the significance of the cortical f0 response to the precise timing of cortical neurons that serve as a time-sensitive code for pitch.

Auditory Evoked Responses in Older Adults With Normal Hearing, Untreated, and Treated Age-Related Hearing Loss.

OBJECTIVES: The goal of this study was to identify the effects of auditory deprivation (age-related hearing loss) and auditory stimulation (history of hearing aid use) on the neural registration of sound across two stimulus presentation conditions: (1) equal sound pressure level and (2) equal sensation level. DESIGN: We used a between-groups design, involving three groups of 14 older adults (n = 42; 62 to 84 years): (1) clinically defined normal hearing (≤25 dB from 250 to 8000 Hz, bilaterally), (2) bilateral mild-moderate/moderately severe sensorineural hearing loss who have never used hearing aids, and (3) bilateral mild-moderate/moderately severe sensorineural hearing loss who have worn bilateral hearing aids for at least the past 2 years. RESULTS: There were significant delays in the auditory P1-N1-P2 complex in older adults with hearing loss compared with their normal hearing peers when using equal sound pressure levels for all participants. However, when the degree and configuration of hearing loss were accounted for through the presentation of equal sensation level stimuli, no latency delays were observed. These results suggest that stimulus audibility modulates P1-N1-P2 morphology and should be controlled for when defining deprivation and stimulus-related neuroplasticity in people with hearing loss. Moreover, a history of auditory stimulation, in the form of hearing aid use, does not appreciably alter the neural registration of unaided auditory evoked brain activity when quantified by the P1-N1-P2. CONCLUSIONS: When comparing auditory cortical responses in older adults with and without hearing loss, stimulus audibility, and not hearing loss-related neurophysiological changes, results in delayed response latency for those with age-related hearing loss. Future studies should carefully consider stimulus presentation levels when drawing conclusions about deprivation- and stimulation-related neuroplasticity. Additionally, auditory stimulation, in the form of a history of hearing aid use, does not significantly affect the neural registration of sound when quantified using the P1-N1-P2-evoked response.

Listening and Learning: Cognitive Contributions to the Rehabilitation of Older Adults With and Without Audiometrically Defined Hearing Loss.

Here, we describe some of the ways in which aging negatively affects the way sensory input is transduced and processed within the aging brain and how cognitive work is involved when listening to a less-than-perfect signal. We also describe how audiologic rehabilitation, including hearing aid amplification and listening training, is used to reduce the amount of cognitive resources required for effective auditory communication and conclude with an example of how listening effort is being studied in research laboratories for the purpose(s) of informing clinical practice.

How Can Public Health Approaches and Perspectives Advance Hearing Health Care?

This commentary explores the role of public health programs and themes on hearing health care. Ongoing engagement within the hearing professional community is needed to determine how to change the landscape and identify important features in the evolution of population hearing health care. Why and how to leverage existing public health programs and develop new programs to improve hearing health in older individuals is an important topic. Hearing professionals are encouraged to reflect on these themes and recommendations and join the discussion about the future of hearing science on a population level.

Hearing Impairment and Cognitive Energy: The Framework for Understanding Effortful Listening (FUEL).

The Fifth Eriksholm Workshop on "Hearing Impairment and Cognitive Energy" was convened to develop a consensus among interdisciplinary experts about what is known on the topic, gaps in knowledge, the use of terminology, priorities for future research, and implications for practice. The general term cognitive energy was chosen to facilitate the broadest possible discussion of the topic. It goes back to who described the effects of attention on perception; he used the term psychic energy for the notion that limited mental resources can be flexibly allocated among perceptual and mental activities. The workshop focused on three main areas: (1) theories, models, concepts, definitions, and frameworks; (2) methods and measures; and (3) knowledge translation. We defined effort as the deliberate allocation of mental resources to overcome obstacles in goal pursuit when carrying out a task, with listening effort applying more specifically when tasks involve listening. We adapted Kahneman's seminal (1973) Capacity Model of Attention to listening and proposed a heuristically useful Framework for Understanding Effortful Listening (FUEL). Our FUEL incorporates the well-known relationship between cognitive demand and the supply of cognitive capacity that is the foundation of cognitive theories of attention. Our FUEL also incorporates a motivation dimension based on complementary theories of motivational intensity, adaptive gain control, and optimal performance, fatigue, and pleasure. Using a three-dimensional illustration, we highlight how listening effort depends not only on hearing difficulties and task demands but also on the listener's motivation to expend mental effort in the challenging situations of everyday life.

Self-Reported Hearing Difficulties Among Adults With Normal Audiograms: The Beaver Dam Offspring Study.

OBJECTIVE: Clinicians encounter patients who report experiencing hearing difficulty (HD) even when audiometric thresholds fall within normal limits. When there is no evidence of audiometric hearing loss, it generates debate over possible biomedical and psychosocial etiologies. It is possible that self-reported HDs relate to variables within and/or outside the scope of audiology. The purpose of this study is to identify how often, on a population basis, people with normal audiometric thresholds self-report HD and to identify factors associated with such HDs. DESIGN: This was a cross-sectional investigation of participants in the Beaver Dam Offspring Study. HD was defined as a self-reported HD on a four-item scale despite having pure-tone audiometric thresholds within normal limits (<20 dB HL0.5, 1, 2, 3, 4, 6, 8 kHz bilaterally, at each frequency). Distortion product otoacoustic emissions and word-recognition performance in quiet and with competing messages were also analyzed. In addition to hearing assessments, relevant factors such as sociodemographic and lifestyle factors, environmental exposures, medical history, health-related quality of life, and symptoms of neurological disorders were also examined as possible risk factors. The Center for Epidemiological Studies-Depression was used to probe symptoms associated with depression, and the Medical Outcomes Study Short-Form 36 mental score was used to quantify psychological stress and social and role disability due to emotional problems. The Visual Function Questionnaire-25 and contrast sensitivity test were used to query vision difficulties. RESULTS: Of the 2783 participants, 686 participants had normal audiometric thresholds. An additional grouping variable was created based on the available scores of HD (four self-report questions), which reduced the total dataset to n = 682 (age range, 21-67 years). The percentage of individuals with normal audiometric thresholds who self-reported HD was 12.0% (82 of 682). The prevalence in the entire cohort was therefore 2.9% (82 of 2783). Performance on audiological tests (distortion product otoacoustic emissions and word-recognition tests) did not differ between the group self-reporting HD and the group reporting no HD. A multivariable model controlling for age and sex identified the following risk factors for HD: lower incomes (odds ratio [OR] $50,000+ = 0.55, 95% confidence interval [CI] = 0.30-1.00), noise exposure through loud hobbies (OR = 1.48, 95% CI = 1.15-1.90), or firearms (OR = 2.07, 95% CI = 1.04-4.16). People reporting HD were more likely to have seen a doctor for hearing loss (OR = 12.93, 95% CI = 3.86-43.33) and report symptoms associated with depression (Center for Epidemiological Studies-Depression [OR = 2.39, 95% CI = 1.03-5.54]), vision difficulties (Visual Function Questionnaire-25 [OR = 0.93, 95% CI = 0.89-0.97]), and neuropathy (e.g., numbness, tingling, and loss of sensation [OR = 1.98, 95% CI = 1.14-3.44]). CONCLUSIONS: The authors used a population approach to identify the prevalence and risk factors associated with self-reported HD among people who perform within normal limits on common clinical tests of auditory function. The percentage of individuals with normal audiometric thresholds who self-reported HD was 12.0%, resulting in an overall prevalence of 2.9%. Auditory and nonauditory risk factors were identified, therefore suggesting that future directions aimed at assessing, preventing, and managing these types of HDs might benefit from information outside the traditional scope of audiology.

Plasticity in neuromagnetic cortical responses suggests enhanced auditory object representation.

BACKGROUND: Auditory perceptual learning persistently modifies neural networks in the central nervous system. Central auditory processing comprises a hierarchy of sound analysis and integration, which transforms an acoustical signal into a meaningful object for perception. Based on latencies and source locations of auditory evoked responses, we investigated which stage of central processing undergoes neuroplastic changes when gaining auditory experience during passive listening and active perceptual training. Young healthy volunteers participated in a five-day training program to identify two pre-voiced versions of the stop-consonant syllable 'ba', which is an unusual speech sound to English listeners. Magnetoencephalographic (MEG) brain responses were recorded during two pre-training and one post-training sessions. Underlying cortical sources were localized, and the temporal dynamics of auditory evoked responses were analyzed. RESULTS: After both passive listening and active training, the amplitude of the P2m wave with latency of 200 ms increased considerably. By this latency, the integration of stimulus features into an auditory object for further conscious perception is considered to be complete. Therefore the P2m changes were discussed in the light of auditory object representation. Moreover, P2m sources were localized in anterior auditory association cortex, which is part of the antero-ventral pathway for object identification. The amplitude of the earlier N1m wave, which is related to processing of sensory information, did not change over the time course of the study. CONCLUSION: The P2m amplitude increase and its persistence over time constitute a neuroplastic change. The P2m gain likely reflects enhanced object representation after stimulus experience and training, which enables listeners to improve their ability for scrutinizing fine differences in pre-voicing time. Different trajectories of brain and behaviour changes suggest that the preceding effect of a P2m increase relates to brain processes, which are necessary precursors of perceptual learning. Cautious discussion is required when interpreting the finding of a P2 amplitude increase between recordings before and after training and learning.

Identifying cochlear implant channels with poor electrode-neuron interfaces: electrically evoked auditory brain stem responses measured with the partial tripolar configuration.

OBJECTIVES: The goal of this study was to compare cochlear implant behavioral measures and electrically evoked auditory brain stem responses (EABRs) obtained with a spatially focused electrode configuration. It has been shown previously that channels with high thresholds, when measured with the tripolar configuration, exhibit relatively broad psychophysical tuning curves. The elevated threshold and degraded spatial/spectral selectivity of such channels are consistent with a poor electrode-neuron interface, defined as suboptimal electrode placement or reduced nerve survival. However, the psychophysical methods required to obtain these data are time intensive and may not be practical during a clinical mapping session, especially for young children. Here, we have extended the previous investigation to determine whether a physiological approach could provide a similar assessment of channel functionality. We hypothesized that, in accordance with the perceptual measures, higher EABR thresholds would correlate with steeper EABR amplitude growth functions, reflecting a degraded electrode-neuron interface. DESIGN: Data were collected from six cochlear implant listeners implanted with the HiRes 90k cochlear implant (Advanced Bionics). Single-channel thresholds and most comfortable listening levels were obtained for stimuli that varied in presumed electrical field size by using the partial tripolar configuration, for which a fraction of current (σ) from a center active electrode returns through two neighboring electrodes and the remainder through a distant indifferent electrode. EABRs were obtained in each subject for the two channels having the highest and lowest tripolar (σ = 1 or 0.9) behavioral threshold. Evoked potentials were measured with both the monopolar (σ = 0) and a more focused partial tripolar (σ ≥ 0.50) configuration. RESULTS: Consistent with previous studies, EABR thresholds were highly and positively correlated with behavioral thresholds obtained with both the monopolar and partial tripolar configurations. The Wave V amplitude growth functions with increasing stimulus level showed the predicted effect of shallower growth for the partial tripolar than for the monopolar configuration, but this was observed only for the low-threshold channels. In contrast, high-threshold channels showed the opposite effect; steeper growth functions were seen for the partial tripolar configuration. CONCLUSIONS: These results suggest that behavioral thresholds or EABRs measured with a restricted stimulus can be used to identify potentially impaired cochlear implant channels. Channels having high thresholds and steep growth functions would likely not activate the appropriate spatially restricted region of the cochlea, leading to suboptimal perception. As a clinical tool, quick identification of impaired channels could lead to patient-specific mapping strategies and result in improved speech and music perception.

Aided cortical auditory evoked potentials in response to changes in hearing aid gain.

OBJECTIVE: There is interest in using cortical auditory evoked potentials (CAEPs) to evaluate hearing aid fittings and experience-related plasticity associated with amplification; however, little is known about hearing aid signal processing effects on these responses. The purpose of this study was to determine the effect of clinically relevant hearing aid gain settings, and the resulting in-the-canal signal-to-noise ratios (SNRs), on the latency and amplitude of P1, N1, and P2 waves. DESIGN & SAMPLE: Evoked potentials and in-the-canal acoustic measures were recorded in nine normal-hearing adults in unaided and aided conditions. In the aided condition, a 40-dB signal was delivered to a hearing aid programmed to provide four levels of gain (0, 10, 20, and 30 dB). As a control, unaided stimulus levels were matched to aided condition outputs (i.e. 40, 50, 60, and 70 dB) for comparison purposes. RESULTS: When signal levels are defined in terms of output level, aided CAEPs were surprisingly smaller and delayed relative to unaided CAEPs, probably resulting from increases to noise levels caused by the hearing aid. DISCUSSION: These results reinforce the notion that hearing aids modify stimulus characteristics such as SNR, which in turn affects the CAEP in a way that does not reliably reflect hearing aid gain.

Older adults' perceptions of current and future hearing healthcare services in Australia, England, US and Canada.

OBJECTIVE: A high prevalence of hearing loss in older adults contrasts with a small proportion of people who seek help. Emerging developments in hearing healthcare (HHC) could reduce costs but may not increase access. This study evaluated older adults' perceptions of current and future HHC services in Australia, England, US and Canada to explore potential levers and system improvements. METHODS: Semi-structured focus groups (n = 47) were conducted, and data were analysed using a directed content analysis. Participants were adults 60 years and older with a) no hearing problems; b) hearing problems and hearing aid use; and c) hearing problems and no hearing aid use. RESULTS: Perceived barriers, facilitators and preferences were largely consistent across countries, with stigma and trust in HHC being the barriers most often discussed. CONCLUSION: Although cost and access were consistently deemed important, there may be limited change in help-seeking and HHC uptake unless the key barriers of trust and stigma are addressed. When seeking to undertake transformative change to healthcare it is important to engage recipients of care to understand existing barriers and coproduce a user-centered solution.

Reliability of the Home Hearing Test: Implications for Public Health.

BACKGROUND: The projected increase in the aging population raises concerns about how to manage the health-care needs in a cost-effective way. Within hearing health care, there are presently too few audiologists to meet the expected demand, and training more professionals may not be a feasible way of addressing this problem. For this reason, there is a need to develop different ways of assessing hearing sensitivity that can be conducted accurately and inexpensively when a certified audiologist and/or sound-attenuated booth is unavailable. More specifically, there is a need to determine if the Etymotic Home Hearing Test (HHT) can yield accurate and reliable data from older adults with varying degrees of hearing loss. PURPOSE: To compare audiometric thresholds obtained using the HHT, an automated pure-tone air-conduction test, to those obtained using manual audiometry (MA), among older adults with varying degrees of hearing loss. STUDY SAMPLE: Participants were 112 English-speaking adults (58% Female), aged 60 yr and older. Participants were excluded from this study if otoscopy revealed cerumen impaction and/or suspected ear pathology. INTERVENTION: All participants completed the HHT on tablet computers in a carpeted classroom and MA in a double-walled sound-attenuated booth using insert earphones for both measures. Both measures were completed in the same test session, and the order of testing (MA versus HHT) was counterbalanced. DATA COLLECTION AND ANALYSIS: Absolute differences in threshold measurements (in dB HL) were calculated across all ears (n = 224 ears) and for all frequencies (octave frequencies from 0.5 to 8 kHz). Correlation and multiple linear regression analyses were conducted to determine if thresholds obtained using the HHT significantly correlated with thresholds using MA. Mean thresholds for each method (HHT and MA) were compared using correlation analyses for each test frequency. Multiple linear regression analysis was used to examine the relationship between the four-frequency pure-tone average (PTA) (average threshold at 0.5, 1, 2, and 4 kHz) in the better-hearing ear measured using the HHT and a set of seven independent factors: four-frequency PTA in the better-hearing ear measured via MA, treatment group (HHT versus MA), age, gender, and degree of hearing loss (mild, moderate, and >moderate). RESULTS: Correlation analyses revealed significant frequency-specific correlations, ranging from 0.91 to 0.97 (p < 0.001), for air-conduction thresholds obtained using the HHT and MA. Mean HHT thresholds were significantly correlated with mean MA thresholds in both ears across the frequency range. This relationship held true across different degrees of hearing loss. The regression model accounted for a significant amount of variance in the HHT better-ear PTA, with MA better-ear PTA being the only significant predictor in our final model, with no effect of degree of loss, age, or gender. CONCLUSIONS: The HHT is an accurate and cost-effective method of establishing pure-tone air-conduction thresholds, when compared with MA. Therefore, the HHT can be used as a tool to acquire accurate air-conduction hearing thresholds from older adults, in-group settings, without the use of a sound-attenuated booth or a certified audiologist.

Aging in binaural hearing begins in mid-life: evidence from cortical auditory-evoked responses to changes in interaural phase.

Older adults often have difficulty understanding speech in a noisy environment or with multiple speakers. In such situations, binaural hearing improves the signal-to-noise ratio. How does this binaural advantage change with increasing age? Using magnetoencephalography, we recorded cortical activity evoked by changes in interaural phase differences of amplitude-modulated tones. These responses occurred for frequencies up to 1225 Hz in young subjects but only up to 940 Hz in middle-aged and 760 Hz in older adults. Behavioral thresholds also decreased with increasing age but were more variable, likely because some older adults make effective use of compensatory mechanisms. The reduced frequency range for binaural hearing became significant in middle age, before decline in hearing sensation and the morphology of cortical responses, which became apparent only in the older subjects. This study provides evidence from human physiological data for the early onset of biological aging in binaural hearing.

Effects of hearing aid amplification and stimulus intensity on cortical auditory evoked potentials.

Hearing aid amplification can be used as a model for studying the effects of auditory stimulation on the central auditory system (CAS). We examined the effects of stimulus presentation level on the physiological detection of sound in unaided and aided conditions. P1, N1, P2, and N2 cortical evoked potentials were recorded in sound field from 13 normal-hearing young adults in response to a 1000-Hz tone presented at seven stimulus intensity levels. As expected, peak amplitudes increased and peak latencies decreased with increasing intensity for unaided and aided conditions. However, there was no significant effect of amplification on latencies or amplitudes. Taken together, these results demonstrate that 20 dB of hearing aid gain affects neural responses differently than 20 dB of stimulus intensity change. Hearing aid signal processing is discussed as a possible contributor to these results. This study demonstrates (1) the importance of controlling for stimulus intensity when evoking responses in aided conditions, and (2) the need to better understand the interaction between the hearing aid and the CAS.

New perspectives on assessing amplification effects.

Clinicians have long been aware of the range of performance variability with hearing aids. Despite improvements in technology, there remain many instances of well-selected and appropriately fitted hearing aids whereby the user reports minimal improvement in speech understanding. This review presents a multistage framework for understanding how a hearing aid affects performance. Six stages are considered: (1) acoustic content of the signal, (2) modification of the signal by the hearing aid, (3) interaction between sound at the output of the hearing aid and the listener's ear, (4) integrity of the auditory system, (5) coding of available acoustic cues by the listener's auditory system, and (6) correct identification of the speech sound. Within this framework, this review describes methodology and research on 2 new assessment techniques: acoustic analysis of speech measured at the output of the hearing aid and auditory evoked potentials recorded while the listener wears hearing aids. Acoustic analysis topics include the relationship between conventional probe microphone tests and probe microphone measurements using speech, appropriate procedures for such tests, and assessment of signal-processing effects on speech acoustics and recognition. Auditory evoked potential topics include an overview of physiologic measures of speech processing and the effect of hearing loss and hearing aids on cortical auditory evoked potential measurements in response to speech. Finally, the clinical utility of these procedures is discussed.

Effect of probe tube insertion depth on spectral measures of speech.

This study investigated how depth variations in the tip of the probe tube affected spectral measures of speech recorded in the external ear canal. Consonant-vowel nonsense syllables were recorded with a probe tube microphone system in 10 adult participants with normal middle ear function. Recordings were made with the probe tube tip placed 1 mm, 5 mm, and 10 mm beyond the medial tip of a custom earmold. The effect of probe depth was evaluated on spectral levels (one-third octave and one- twelfth octave band). Extending the probe tube 10 mm past the medial tip of the earmold gave the most accurate results, with relatively lower sound levels for either the 1-mm or 5-mm insertion depth. In general, the effect of insertion depth was minimal at frequencies below 3 to 4 kHz, although this varied with the specific phoneme and the width of the analysis bands. The authors found no significant difference between 1- and 5-mm insertion depths, suggesting that as long as the tip of the probe tube is sufficiently close to the tympanic membrane to capture the highest frequency of interest, it makes little difference if it is less than 5 mm beyond the earmold tip.

The neural representation of consonant-vowel transitions in adults who wear hearing AIDS.

Hearing aids help compensate for disorders of the ear by amplifying sound; however, their effectiveness also depends on the central auditory system's ability to represent and integrate spectral and temporal information delivered by the hearing aid. The authors report that the neural detection of time-varying acoustic cues contained in speech can be recorded in adult hearing aid users using the acoustic change complex (ACC). Seven adults (50-76 years) with mild to severe sensorineural hearing participated in the study. When presented with 2 identifiable consonant-vowel (CV) syllables ("shee" and "see"), the neural detection of CV transitions (as indicated by the presence of a P1-N1-P2 response) was different for each speech sound. More specifically, the latency of the evoked neural response coincided in time with the onset of the vowel, similar to the latency patterns the authors previously reported in normal-hearing listeners.

Aided Electrophysiology Using Direct Audio Input: Effects of Amplification and Absolute Signal Level.

PURPOSE: This study investigated (a) the effect of amplification on cortical auditory evoked potentials (CAEPs) at different signal levels when signal-to-noise ratios (SNRs) were equated between unaided and aided conditions, and (b) the effect of absolute signal level on aided CAEPs when SNR was held constant. METHOD: CAEPs were recorded from 13 young adults with normal hearing. A 1000-Hz pure tone was presented in unaided and aided conditions with a linear analog hearing aid. Direct audio input was used, allowing recorded hearing aid noise floor to be added to unaided conditions to equate SNRs between conditions. An additional stimulus was created through scaling the noise floor to study the effect of signal level. RESULTS: Amplification resulted in delayed N1 and P2 peak latencies relative to the unaided condition. An effect of absolute signal level (when SNR was constant) was present for aided CAEP area measures, such that larger area measures were found at higher levels. CONCLUSION: Results of this study further demonstrate that factors in addition to SNR must also be considered before CAEPs can be used to clinically to measure aided thresholds.

Aging and Hearing Health: The Life-course Approach.

Sensory abilities decline with age. More than 5% of the world's population, approximately 360 million people, have disabling hearing loss. In adults, disabling hearing loss is defined by thresholds greater than 40 dBHL in the better hearing ear.Hearing disability is an important issue in geriatric medicine because it is associated with numerous health issues, including accelerated cognitive decline, depression, increased risk of dementia, poorer balance, falls, hospitalizations, and early mortality. There are also social implications, such as reduced communication function, social isolation, loss of autonomy, impaired driving ability, and financial decline. Furthermore, the onset of hearing loss is gradual and subtle, first affecting the detection of high-pitched sounds and with difficulty understanding speech in noisy but not in quiet environments. Consequently, delays in recognizing and seeking help for hearing difficulties are common. Age-related hearing loss has no known cure, and technologies (hearing aids, cochlear implants, and assistive devices) improve thresholds but do not restore hearing to normal. Therefore, health care for persons with hearing loss and people within their communication circles requires education and counseling (e.g., increasing knowledge, changing attitudes, and reducing stigma), behavior change (e.g., adapting communication strategies), and environmental modifications (e.g., reducing noise). In this article, we consider the causes, consequences, and magnitude of hearing loss from a life-course perspective. We examine the concept of "hearing health," how to achieve it, and implications for policy and practice.

The Ear-Brain Connection: Older Ears and Older Brains.

PURPOSE: The purpose of this article is to review recent research from our laboratory on the topic of aging, and the ear-brain system, as it relates to hearing aid use and auditory rehabilitation. The material described here was presented as part of the forum on the brain and hearing aids, at the 2014 HEaling Across the Lifespan (HEAL) conference. METHOD: The method involves a narrative review of previously reported electroencephalography (EEG) and magnetoencephalography (MEG) data from our laboratory as they relate to the (a) neural detection of amplified sound and (b) ability to learn new sound contrasts. CONCLUSIONS: Results from our studies add to the mounting evidence that there are central effects of biological aging as well as peripheral pathology that affect a person's neural detection and use of sound. What is more, these biological effects can be seen as early as middle age. The accruing evidence has implications for hearing aid use because effective communication relies not only on sufficient detection of sound but also on the individual's ability to learn to make use of these sounds in ever-changing listening environments.

Aging alters the neural representation of speech cues.

Age-related deficits in speech understanding are well documented. Because speech is a complex signal, containing time-varying acoustic cues, it is frequently hypothesized that aging adversely affects the ability to process temporal cues. This study examined the neural representation and perception of voice-onset-time, a temporal cue that distinguishes voiced /b/ from voiceless /p/ sounds. We found that older adults had more difficulty than younger listeners discriminating voice-onset contrasts. In addition, these same speech stimuli evoked abnormal neural responses in older adults. That is, compared with younger listeners, N1 and P2 long-latency auditory evoked responses were prolonged for older adults. Collectively, these results suggest speech perception difficulties described by older adults may be related to age-related changes regulating excitatory and inhibitory processes.