Normal Hearing Age Research Articles

Self-pacing ameliorates recall deficit when listening to vocoded discourse: a cochlear implant simulation.

In spite of its apparent ease, comprehension of spoken discourse represents a complex linguistic and cognitive operation. The difficulty of such an operation can increase when the speech is degraded, as is the case with cochlear implant users. However, the additional challenges imposed by degraded speech may be mitigated to some extent by the linguistic context and pace of presentation. An experiment is reported in which young adults with age-normal hearing recalled discourse passages heard with clear speech or with noise-band vocoding used to simulate the sound of speech produced by a cochlear implant. Passages were varied in inter-word predictability and presented either without interruption or in a self-pacing format that allowed the listener to control the rate at which the information was delivered. Results showed that discourse heard with clear speech was better recalled than discourse heard with vocoded speech, discourse with a higher average inter-word predictability was better recalled than discourse with a lower average inter-word predictability, and self-paced passages were recalled better than those heard without interruption. Of special interest was the semantic hierarchy effect: the tendency for listeners to show better recall for main ideas than mid-level information or detail from a passage as an index of listeners' ability to understand the meaning of a passage. The data revealed a significant effect of inter-word predictability, in that passages with lower predictability had an attenuated semantic hierarchy effect relative to higher-predictability passages. Results are discussed in terms of broadening cochlear implant outcome measures beyond current clinical measures that focus on single-word and sentence repetition.

Noise-Vocoded Sentence Recognition and the Use of Context in Older and Younger Adult Listeners.

When listening to speech under adverse conditions, older adults, even with "age-normal" hearing, face challenges that may lead to poorer speech recognition than their younger peers. Older listeners generally demonstrate poorer suprathreshold auditory processing along with aging-related declines in neurocognitive functioning that may impair their ability to compensate using "top-down" cognitive-linguistic functions. This study explored top-down processing in older and younger adult listeners, specifically the use of semantic context during noise-vocoded sentence recognition. Eighty-four adults with age-normal hearing (45 young normal-hearing [YNH] and 39 older normal-hearing [ONH] adults) participated. Participants were tested for recognition accuracy for two sets of noise-vocoded sentence materials: one that was semantically meaningful and the other that was syntactically appropriate but semantically anomalous. Participants were also tested for hearing ability and for neurocognitive functioning to assess working memory capacity, speed of lexical access, inhibitory control, and nonverbal fluid reasoning, as well as vocabulary knowledge. The ONH and YNH listeners made use of semantic context to a similar extent. Nonverbal reasoning predicted recognition of both meaningful and anomalous sentences, whereas pure-tone average contributed additionally to anomalous sentence recognition. None of the hearing, neurocognitive, or language measures significantly predicted the amount of context gain, computed as the difference score between meaningful and anomalous sentence recognition. However, exploratory cluster analyses demonstrated four listener profiles and suggested that individuals may vary in the strategies used to recognize speech under adverse listening conditions. Older and younger listeners made use of sentence context to similar degrees. Nonverbal reasoning was found to be a contributor to noise-vocoded sentence recognition. However, different listeners may approach the problem of recognizing meaningful speech under adverse conditions using different strategies based on their hearing, neurocognitive, and language profiles. These findings provide support for the complexity of bottom-up and top-down interactions during speech recognition under adverse listening conditions.

Word and Nonword Reading Efficiency in Postlingually Deafened Adult Cochlear Implant Users.

This study tested the hypotheses that 1) experienced adult cochlear implants (CI) users demonstrate poorer reading efficiency relative to normal-hearing controls, 2) reading efficiency reflects basic, underlying neurocognitive skills, and 3) reading efficiency relates to speech recognition outcomes in CI users. Weak phonological processing skills have been associated with poor speech recognition outcomes in postlingually deaf adult CI users. Phonological processing can be captured in nonauditory measures of reading efficiency, which may have wide use in patients with hearing loss. This study examined reading efficiency in adults CI users, and its relation to speech recognition outcomes. Forty-eight experienced, postlingually deaf adult CI users (ECIs) and 43 older age-matched peers with age-normal hearing (ONHs) completed the Test of Word Reading Efficiency (TOWRE-2), which measures word and nonword reading efficiency. Participants also completed a battery of nonauditory neurocognitive measures and auditory sentence recognition tasks. ECIs and ONHs did not differ in word (ECIs: M = 78.2, SD = 11.4; ONHs: M = 83.3, SD = 10.2) or nonword reading efficiency (ECIs: M = 42.0, SD = 11.2; ONHs: M = 43.7, SD = 10.3). For ECIs, both scores were related to untimed word reading with moderate to strong effect sizes (r = 0.43-0.69), but demonstrated differing relations with other nonauditory neurocognitive measures with weak to moderate effect sizes (word: r = 0.11-0.44; nonword: r = (-)0.15 to (-)0.42). Word reading efficiency was moderately related to sentence recognition outcomes in ECIs (r = 0.36-0.40). Findings suggest that postlingually deaf adult CI users demonstrate neither impaired word nor nonword reading efficiency, and these measures reflect different underlying mechanisms involved in language processing. The relation between sentence recognition and word reading efficiency, a measure of lexical access speed, suggests that this measure may be useful for explaining outcome variability in adult CI users.

Restoration of auditory network after cochlear implant in prelingual deafness: a P300 study using LORETA.

SUMMARYThe concept of auditory restoration after cochlear implant (CI) in prelingual deafness is well described by a synaptic network model, whose development depends on sensory experience. The aim of this work was to study the associative networks activated by the CI in a population of prelingually deaf patients. In particular, the impact of age at time of first CI fitting and duration of CI use was evaluated. Twenty patients were tested and divided into three groups: early implanted and lengthy CI use (group A); late implanted and lengthy CI use (group B); late implanted and short CI use (group C). Each patient group was compared with a normal hearing age matched control group. All subjects underwent to auditory event-related potentials (ERPs) registration. ERP latencies and their cortical sources were investigated. Cortical source analysis was performed using LORETA (Low Resolution Electromagnetic Tomography) software. P300 latencies were significantly longer in patients than in controls. The amount of cortical activation was found to be significantly directly correlated with duration of implant use and significantly correlated inversely with age at implant. When comparing patients and controls, comparable cortical activation was only found in A patient group, and to a lesser extent in group B, while significantly lower activation was found in patient group C in the frontal and cingulate areas. CI adds a sensory modality in deafness patients, i.e. the auditory one. This involves areas implicated in sensory and cognitive functions, and needs some time to form. The duration of CI use is crucial: our results demonstrate the importance of long term use of the device in addition to an early time of implant.

Variations Within Normal Hearing Acuity and Speech Comprehension: An Exploratory Study.

Purpose Many young adults with a mild hearing loss can appear unaware or unconcerned about their loss or its potential effects. A question that has not been raised in prior research is whether slight variability, even within the range of clinically normal hearing, may have a detrimental effect on comprehension of spoken sentences, especially when attempting to understand the meaning of sentences that offer an additional cognitive challenge. The purpose of this study was to address this question. Method An exploratory analysis was conducted on data from 3 published studies that included young adults, ages 18 to 29 years, with audiometrically normal hearing acuity (pure-tone average < 15 dB HL) tested for comprehension of sentences that conveyed the sentence meaning with simpler or more complex linguistic structures. A product-moment correlation was conducted between individuals' hearing acuity and their comprehension accuracy. Results A significant correlation appeared between hearing acuity and comprehension accuracy for syntactically complex sentences, but not for sentences with a simpler syntactic structure. Partial correlations confirmed this relationship to hold independent of participant age within this relatively narrow age range. Conclusion These findings suggest that slight elevations in hearing thresholds, even among young adults who pass a screen for normal hearing, can affect comprehension accuracy for spoken sentences when combined with cognitive demands imposed by sentences that convey their meaning with a complex linguistic structure. These findings support limited resource models of attentional allocation and argue for routine baseline hearing evaluations of young adults with current age-normal hearing acuity.

Speech Recognition in Adults With Cochlear Implants: The Effects of Working Memory, Phonological Sensitivity, and Aging.

Models of speech recognition suggest that "top-down" linguistic and cognitive functions, such as use of phonotactic constraints and working memory, facilitate recognition under conditions of degradation, such as in noise. The question addressed in this study was what happens to these functions when a listener who has experienced years of hearing loss obtains a cochlear implant. Thirty adults with cochlear implants and 30 age-matched controls with age-normal hearing underwent testing of verbal working memory using digit span and serial recall of words. Phonological capacities were assessed using a lexical decision task and nonword repetition. Recognition of words in sentences in speech-shaped noise was measured. Implant users had only slightly poorer working memory accuracy than did controls and only on serial recall of words; however, phonological sensitivity was highly impaired. Working memory did not facilitate speech recognition in noise for either group. Phonological sensitivity predicted sentence recognition for implant users but not for listeners with normal hearing. Clinical speech recognition outcomes for adult implant users relate to the ability of these users to process phonological information. Results suggest that phonological capacities may serve as potential clinical targets through rehabilitative training. Such novel interventions may be particularly helpful for older adult implant users.

Verbal Working Memory in Older Adults: The Roles of Phonological Capacities and Processing Speed.

This study examined the potential roles of phonological sensitivity and processing speed in age-related declines of verbal working memory. Twenty younger and 25 older adults with age-normal hearing participated. Two measures of verbal working memory were collected: digit span and serial recall of words. Processing speed was indexed using response times during those tasks. Three other measures were also obtained, assessing phonological awareness, processing, and recoding. Forward and reverse digit spans were similar across groups. Accuracy on the serial recall task was poorer for older than for younger adults, and response times were slower. When response time served as a covariate, the age effect for accuracy was reduced. Phonological capacities were equivalent across age groups, so we were unable to account for differences across age groups in verbal working memory. Nonetheless, when outcomes for only older adults were considered, phonological awareness and processing speed explained significant proportions of variance in serial recall accuracy. Slowing in processing abilities accounts for the primary trajectory of age-related declines in verbal working memory. However, individual differences in phonological capacities explain variability among individual older adults.

Multiple Solutions to the Same Problem: Utilization of Plausibility and Syntax in Sentence Comprehension by Older Adults with Impaired Hearing.

A fundamental question in psycholinguistic theory is whether equivalent success in sentence comprehension may come about by different underlying operations. Of special interest is whether adult aging, especially when accompanied by reduced hearing acuity, may shift the balance of reliance on formal syntax vs. plausibility in determining sentence meaning. In two experiments participants were asked to identify the thematic roles in grammatical sentences that contained either plausible or implausible semantic relations. Comprehension of sentence meanings was indexed by the ability to correctly name the agent or the recipient of an action represented in the sentence. In Experiment 1 young and older adults’ comprehension was tested for plausible and implausible sentences with the meaning expressed with either an active-declarative or a passive syntactic form. In Experiment 2 comprehension performance was examined for young adults with age-normal hearing, older adults with good hearing acuity, and age-matched older adults with mild-to-moderate hearing loss for plausible or implausible sentences with meaning expressed with either a subject-relative (SR) or an object-relative (OR) syntactic structure. Experiment 1 showed that the likelihood of interpreting a sentence according to its literal meaning was reduced when that meaning expressed an implausible relationship. Experiment 2 showed that this likelihood was further decreased for OR as compared to SR sentences, and especially so for older adults whose hearing impairment added to the perceptual challenge. Experiment 2 also showed that working memory capacity as measured with a letter-number sequencing task contributed to the likelihood that listeners would base their comprehension responses on the literal syntax even when this processing scheme yielded an implausible meaning. Taken together, the results of both experiments support the postulate that listeners may use more than a single uniform processing strategy for successful sentence comprehension, with the existence of these alternative solutions only revealed when literal syntax and plausibility do not coincide.

The Two Sides of Sensory-Cognitive Interactions: Effects of Age, Hearing Acuity, and Working Memory Span on Sentence Comprehension.

Reduced hearing acuity is among the most prevalent of chronic medical conditions among older adults. An experiment is reported in which comprehension of spoken sentences was tested for older adults with good hearing acuity or with a mild-to-moderate hearing loss, and young adults with age-normal hearing. Comprehension was measured by participants’ ability to determine the agent of an action in sentences that expressed this relation with a syntactically less complex subject-relative construction or a syntactically more complex object-relative construction. Agency determination was further challenged by inserting a prepositional phrase into sentences between the person performing an action and the action being performed. As a control, prepositional phrases of equivalent length were also inserted into sentences in a non-disruptive position. Effects on sentence comprehension of age, hearing acuity, prepositional phrase placement and sound level of stimulus presentations appeared only for comprehension of sentences with the more syntactically complex object-relative structures. Working memory as tested by reading span scores accounted for a significant amount of the variance in comprehension accuracy. Once working memory capacity and hearing acuity were taken into account, chronological age among the older adults contributed no further variance to comprehension accuracy. Results are discussed in terms of the positive and negative effects of sensory–cognitive interactions in comprehension of spoken sentences and lend support to a framework in which domain-general executive resources, notably verbal working memory, play a role in both linguistic and perceptual processing.

The Contribution of Auditory and Cognitive Factors to Intelligibility of Words and Sentences in Noise.

Understanding the causes for speech-in-noise (SiN) perception difficulties is complex, and is made even more difficult by the fact that listening situations can vary widely in target and background sounds. While there is general agreement that both auditory and cognitive factors are important, their exact relationship to SiN perception across various listening situations remains unclear. This study manipulated the characteristics of the listening situation in two ways: first, target stimuli were either isolated words, or words heard in the context of low- (LP) and high-predictability (HP) sentences; second, the background sound, speech-modulated noise, was presented at two signal-to-noise ratios. Speech intelligibility was measured for 30 older listeners (aged 62-84) with age-normal hearing and related to individual differences in cognition (working memory, inhibition and linguistic skills) and hearing (PTA(0.25-8 kHz) and temporal processing). The results showed that while the effect of hearing thresholds on intelligibility was rather uniform, the influence of cognitive abilities was more specific to a certain listening situation. By revealing a complex picture of relationships between intelligibility and cognition, these results may help us understand some of the inconsistencies in the literature as regards cognitive contributions to speech perception.

Aging and speech perception: beyond hearing threshold and cognitive ability

Older adults manifest difficulties in speech perception, especially when speech is accompanied by noise or when speech is rapid. Several explanations have been suggested to account for age-related changes in speech perception, such as changes in hearing sensitivity or a more general decline in cognitive functioning. The purpose of the present study was to directly examine the relative contribution of hearing sensitivity and perceptual and cognitive factors in the understanding of age-related differences in speech perception under difficult conditions. Eighty-nine healthy participants with normal hearing thresholds, age 21-82 years, were tested for speech perception under four conditions: quiet, speech noise, white noise, and time-compressed speech at 60% compression rate. As all participants had age-normal hearing, absolute thresholds were tested for click trains, 1 kHz 15-ms duration pure tone, 1 kHz 50-ms duration pure tone, and 1.8 kHz 15-ms duration pure tone, which are relatively short and discriminative for hearing ability. Cognitive ability was examined using the Wechsler Adult Intelligence Scale (Third Edition) matrices and digit span. When words were presented against a quiet background or against white noise, speech perception was not significantly affected by aging, although in the latter case, increased thresholds predicted poorer speech perception. However, when words were presented against a background of speech noise or when speech was time-compressed at a 60% rate, age significantly predicted a decline in speech perception, even after controlling for hearing thresholds and cognitive functioning. Hearing threshold for short sounds is the major factor for predicting speech perception in background noise, across age, due to changes in hearing sensitivity or in temporal resolution. For the adult and aging population with preserved cognitive ability, cognitive functioning does not predict decline in speech perception.

Expectation and Entropy in Spoken Word Recognition: Effects of Age and Hearing Acuity

Background/Study Context: Older adults, especially those with reduced hearing acuity, can make good use of linguistic context in word recognition. Less is known about the effects of the weighted distribution of probable target and nontarget words that fit the sentence context (response entropy). The present study examined the effects of age, hearing acuity, linguistic context, and response entropy on spoken word recognition. Methods: Participants were 18 older adults with good hearing acuity (M age = 74.3 years), 18 older adults with mild-to-moderate hearing loss (M age = 76.1 years), and 18 young adults with age-normal hearing (M age = 19.6 years). Participants heard sentence-final words using a word-onset gating paradigm, in which words were heard with increasing amounts of onset information until they could be correctly identified. Degrees of context varied from a neutral context to a high context condition. Results: Older adults with poor hearing acuity required a greater amount of word onset information for recognition of words when heard in a neutral context compared with older adults with good hearing acuity and young adults. This difference progressively decreased with an increase in words’ contextual probability. Unlike the young adults, both older adult groups’ word recognition thresholds were sensitive to response entropy. Response entropy was not affected by hearing acuity. Conclusion: Increasing linguistic context mitigates the negative effect of age and hearing loss on word recognition. The effect of response entropy on older adults’ word recognition is discussed in terms of an age-related inhibition deficit.

The hidden effect of hearing acuity on speech recall, and compensatory effects of self-paced listening

Objective: The purpose of this research was to determine whether negative effects of hearing loss on recall accuracy for spoken narratives can be mitigated by allowing listeners to control the rate of speech input. Design: Paragraph-length narratives were presented for recall under two listening conditions in a within-participants design: presentation without interruption (continuous) at an average speech-rate of 150 words per minute; and presentation interrupted at periodic intervals at which participants were allowed to pause before initiating the next segment (self-paced). Study sample: Participants were 24 adults ranging from 21 to 33 years of age. Half had age-normal hearing acuity and half had mild- to-moderate hearing loss. The two groups were comparable for age, years of formal education, and vocabulary. Results: When narrative passages were presented continuously, without interruption, participants with hearing loss recalled significantly fewer story elements, both main ideas and narrative details, than those with age-normal hearing. The recall difference was eliminated when the two groups were allowed to self-pace the speech input. Conclusion: Results support the hypothesis that the listening effort associated with reduced hearing acuity can slow processing operations and increase demands on working memory, with consequent negative effects on accuracy of narrative recall.

Acoustic Analysis of Speech of Cochlear Implantees and Its Implications

ObjectivesCochlear implantees have improved speech production skills compared with those using hearing aids, as reflected in their acoustic measures. When compared to normal hearing controls, implanted children had fronted vowel space and their /s/ and /∫/ noise frequencies overlapped. Acoustic analysis of speech provides an objective index of perceived differences in speech production which can be precursory in planning therapy. The objective of this study was to compare acoustic characteristics of speech in cochlear implantees with those of normal hearing age matched peers to understand implications.MethodsGroup 1 consisted of 15 children with prelingual bilateral severe-profound hearing loss (age, 5-11 years; implanted between 4-10 years). Prior to an implant behind the ear, hearing aids were used; prior & post implantation subjects received at least 1 year of aural intervention. Group 2 consisted of 15 normal hearing age matched peers. Sustained productions of vowels and words with selected consonants were recorded. Using Praat software for acoustic analysis, digitized speech tokens were measured for F1, F2, and F3 of vowels; centre frequency (Hz) and energy concentration (dB) in burst; voice onset time (VOT in ms) for stops; centre frequency (Hz) of noise in /s/; rise time (ms) for affricates. A t-test was used to find significant differences between groups.ResultsSignificant differences were found in VOT for /b/, F1 and F2 of /e/, and F3 of /u/. No significant differences were found for centre frequency of burst, energy concentration for stops, centre frequency of noise in /s/, or rise time for affricates. These findings suggest that auditory feedback provided by cochlear implants enable subjects to monitor production of speech sounds.ConclusionAcoustic analysis of speech is an essential method for discerning characteristics which have or have not been improved by cochlear implantation and thus for planning intervention.

Evaluation of central neuropathy in patients of chronic renal failure with normal hearing

Aims and Objective: The aim of the study was to study the involvement of inner ear and eighth nerve in patients of chronic renal failure (CRF) with normal hearing. Further, the mean absolute and inter-peak latencies were correlated with the duration of disease, blood urea level, and the severity of the disease. Materials and Methods: A total of 46 patients of CRF with normal hearing (29 males and 17 females) were included in the study. Majority of the patients were in 21 to 40 year age group. Mean absolute latencies of wave I, III, and V, and inter-peak wave latencies I-III, III-V, and I-V were calculated and compared with the mean wave latencies in 15 normal hearing age- and sex-matched control subjects. Student's t test was applied to evaluate the significance of delay in wave latencies. The patients were divided on the basis of the duration of disease (less than 2 years and more than 2 years), blood urea level (less than 200 mg% and more than 200 mg%), and severity of disease (Patients with glomerular filtration rate [GFR] less than 60 mL/min/1.73 m 2 but more than 10 mL and patients with GFR less than 10 mL/min/1.73 m 2). The significant differences between the hearing thresholds of these two groups were assessed using student's t test for unequal samples. Results: There was a statistically significant delay in absolute latencies of wave I, III, and V and inter-peak latencies I-III, III-V, and I-V. Mean wave latencies with values outside mean ± 2 SD of control were considered as abnormal. Abnormal absolute wave latencies and inter-peak latencies were present in 63.05% and 67.39% of cases, respectively. There was a significant delay in mean absolute latency of wave V and mean inter-peak latency of wave I-III, III-V, and I-V in patients of CRF with duration of disease more than 2 years as compared with patients of CRF with duration of disease less than 2 years. There was a significant delay in mean absolute latency of wave III and V and mean inter-peak latency of wave I-III, III-V, and I-V in patients of CRF with blood urea level more than 200 mg% as compared to patients of CRF with blood urea level less than 200 mg%. There was a significant delay in mean absolute latency of wave III and V and mean inter-peak latency of wave I-III, III-V, and I-V in patients of CRF with GFR less than 10 as compared with patients of CRF with GFR less than 60 but more than 10. Conclusion: The study suggests the involvement of central neural axis and auditory end organ in patients of CRF with normal hearing. It further establishes the role of brainstem evoked response audiometry in earlier detection of central neural axis and auditory end organ. As the duration of disease increases, inferior colliculus and auditory pathway is more prone to damage by uremic neuropathy. An increase in blood urea and decrease in GFR (severity of disease) leads to uremic neuropathy causing damage to superior olivary nucleus and inferior colliculus. Increased blood urea also causes delay in inter-peak latencies, suggesting diffuse axonal neuropathy in patients of CRF.

Assessment of Hyperacusis in Egyptian patients: Evaluation of the Arabic version of the Khalfa questionnaire

AbstractObjectives: Hyperacusis appears to be a subjective phenomenon, which is not easily defined or quantified by objective measurements. The primary aim of this work was to evaluate the Arabic version of the Khalfa questionnaire for hyperacusis on a sample of normal hearing Egyptians complaining of hyperacusis. The secondary aim was to compare the audiological criteria of this group of hyperacusis patients (with or without tinnitus) with a control group of similar age and gender. Study design: The study group comprised 60 adult patients (age range 19–45 years) having normal hearing and complaining of hyperacusis with or without tinnitus. The control group comprised 20 normal hearing age and gender-matched individuals. All patients were subjected to full history-taking, otological examination, pure tone audiometry, immittance audiometry, uncomfortable loudness levels (ULLs) assessment, a transient evoked otoacoustic emissions (TEOAEs) test and, in addition, to the Arabic version of the Khalfa hyperacusi...

Hearing Loss in Older Adults Affects Neural Systems Supporting Speech Comprehension

Hearing loss is one of the most common complaints in adults over the age of 60 and a major contributor to difficulties in speech comprehension. To examine the effects of hearing ability on the neural processes supporting spoken language processing in humans, we used functional magnetic resonance imaging to monitor brain activity while older adults with age-normal hearing listened to sentences that varied in their linguistic demands. Individual differences in hearing ability predicted the degree of language-driven neural recruitment during auditory sentence comprehension in bilateral superior temporal gyri (including primary auditory cortex), thalamus, and brainstem. In a second experiment, we examined the relationship of hearing ability to cortical structural integrity using voxel-based morphometry, demonstrating a significant linear relationship between hearing ability and gray matter volume in primary auditory cortex. Together, these results suggest that even moderate declines in peripheral auditory acuity lead to a systematic downregulation of neural activity during the processing of higher-level aspects of speech, and may also contribute to loss of gray matter volume in primary auditory cortex. More generally, these findings support a resource-allocation framework in which individual differences in sensory ability help define the degree to which brain regions are recruited in service of a particular task.

Bimodal Stimulus Presentation and Expanded Auditory Bandwidth Improve Older Adults’ Speech Perception

A pair of experiments investigated the hypothesis that bimodal (auditory-visual) speech presentation and expanded auditory bandwidth would improve speech intelligibility and increase working memory performance for older adults by reducing the cognitive effort needed for speech perception. Although telephone communication is important for helping older adults maintain social engagement, age-related sensory and working memory limits may make telephone conversations difficult. Older adults with either age-normal hearing or mild-to-moderate sensorineural hearing loss performed a running memory task. Participants heard word strings of unpredictable length and at the end of each string were required to repeat back the final three words.Words were presented monaurally in telephone bandwidth (300 Hz to 3300 Hz) or expanded bandwidth (50 Hz to 7500 Hz), in quiet (65 dBZ SPL), or in white noise (65 dBZ SPL with noise at 60 dBZ SPL), with or without a visual display of the talker. In quiet listening conditions, bimodal presentation increased the number of words correctly reported per trial but only for listeners with hearing loss and with high lipreading proficiency. Stimulus bandwidth did not affect performance. In noise, bimodal presentation and expanded bandwidth improved performance for all participant groups but did so by improving speech intelligibility, not by improving working memory. Expanded bandwidth and bimodal presentation can improve speech perceptibility in difficult listening conditions but may not always improve working memory performance. Results can inform the design of telephone features to improve ease of communication for older adults.

Quantification of the mitochondrial DNA common deletion in presbycusis

This study was conducted to evaluate the association between the mitochondrial DNA (mtDNA) common deletion (CD) level in cochlear tissue and the severity of hearing loss in individuals with presbycusis. Nineteen individuals with presbycusis, ranging from 60 to 87 years of age, who met strict audiometric criteria were compared with four age frequency-matched normal hearing controls ranging from 51 to 76 years of age. Five additional normal hearing individuals, ranging from 9 to 50 years of age, were also studied. A duplex real time polymerase chain reaction assay was used to quantify the mtDNA in archival cochlear tissue samples. Linear regression models were used for comparison of the CD level between groups. The presbycusis group had a mean CD level of 32% with a standard deviation of 14%, and the normal hearing age matched control group had a mean CD level of 12% with a standard deviation of 2%. This difference in CD levels reached statistical significance (P = .011) and remained significant after adjusting for any differences in age between the two groups (age-adjusted P = .007). Furthermore, there was evidence for a significant association between the CD level and the severity of hearing loss based on audiometric thresholds at 8 kHz (r = 0.44, P = .034; age-adjusted partial correlation = 0.55, P = .007). For the first time, to our knowledge, these results demonstrate a relationship between quantitatively measured levels of the CD in human cochlear tissue and the severity of hearing loss in individuals with presbycusis. Laryngoscope, 2009.

Hearing loss and cognitive effort in older adults' report accuracy for verbal materials.

In addition to declines in auditory acuity, adult aging is often also accompanied by reduced cognitive efficiency, most notably in working memory resources and a general slowing in a number of perceptual and cognitive domains. Effectiveness of speech comprehension by older adults reflects a balance between these declines and the relative preservation in healthy aging of linguistic knowledge and the procedural rules for its application. To examine effects of hearing acuity in older adults on intelligibility functions for sentences that varied in two degrees of syntactic complexity, with their concomitant demands on older adults' working memory resources. Stimuli consisted of monosyllabic words presented in isolation, and nine-word sentences that varied in syntactic complexity. Two sentence types were employed: sentences with a subject-relative clause structure, and more syntactically complex sentences in which meaning was expressed with an object-relative clause structure. The stimuli were presented initially below the level of audibility and then increased in loudness in 2 dB increments until the single-word stimuli and all nine words of the sentence stimuli could be correctly reported. Participants were 16 older adults with good hearing acuity for their ages, 16 age-matched adults with mild-to-moderate hearing loss, and 16 young adults with age-normal hearing. Along with confirming better report accuracy for the words of meaningful sentences than for words heard in isolation, performance curves for the sentence stimuli showed a significant effect of syntactic complexity. This took the form of older adults having poorer report accuracy at any given loudness level for sentences with greater syntactic complexity. This general effect of syntactic complexity on perceptual report accuracy was further exacerbated by age and hearing loss. Age-limited working memory resources are impacted both by the resource demands required for comprehension of syntactically complex sentences and by effortful listening attendant to hearing loss.