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Ahmmed A.U.,Lancashire Teaching Hospital | Ahmmed A.A.,Newcastle University | Bath J.R.,Lancashire Teaching Hospital | Ferguson M.A.,NIHR National Biomedical Research | And 3 more authors.
Ear and Hearing | Year: 2014

OBJECTIVES:: To identify the factors that may underlie the deficits in children with listening difficulties, despite normal pure-tone audiograms. These children may have auditory processing disorder (APD), but there is no universally agreed consensus as to what constitutes APD. The authors therefore refer to these children as children with suspected APD (susAPD) and aim to clarify the role of attention, cognition, memory, sensorimotor processing speed, speech, and nonspeech auditory processing in susAPD. It was expected that a factor analysis would show how nonauditory and supramodal factors relate to auditory behavioral measures in such children with susAPD. This would facilitate greater understanding of the nature of listening difficulties, thus further helping with characterizing APD and designing multimodal test batteries to diagnose APD. DESIGN:: Factor analysis of outcomes from 110 children (68 male, 42 female; aged 6 to 11 years) with susAPD on a widely used clinical test battery (SCAN-C) and a research test battery (MRC Institute of Hearing Research Multi-center Auditory Processing "IMAP"), that have age-based normative data. The IMAP included backward masking, simultaneous masking, frequency discrimination, nonverbal intelligence, working memory, reading, alerting attention and motor reaction times to auditory and visual stimuli. SCAN-C included monaural low-redundancy speech (auditory closure and speech in noise) and dichotic listening tests (competing words and competing sentences) that assess divided auditory attention and hence executive attention. RESULTS:: Three factors were extracted: "general auditory processing," "working memory and executive attention," and "processing speed and alerting attention." Frequency discrimination, backward masking, simultaneous masking, and monaural low-redundancy speech tests represented the "general auditory processing" factor. Dichotic listening and the IMAP cognitive tests (apart from nonverbal intelligence) were represented in the "working memory and executive attention" factor. Motor response times to cued and noncued auditory and visual stimuli were grouped in the "processing speed and alerting attention" factor. Individuals varied in their outcomes in different tests. Poor performance was noted in different combinations of tests from the three factors. Impairments solely related to the "general auditory processing" factor were not common. CONCLUSIONS:: The study identifies a general auditory processing factor in addition to two other cognitive factors, "working memory and executive attention" and "processing speed and alerting attention," to underlie the deficits in children with susAPD. Impaired attention, memory, and processing speed are known to be associated with poor literacy and numeracy skills as well as a number of neurodevelopmental disorders. Individuals with impairments in the "general auditory processing" tests along with tests from the other two cognitive factors may explain the co-occurrence of APD and other disorders. The variation in performance by individuals in the different tests noted was probably due to a number of reasons including heterogeneity in susAPD and less-than ideal test-retest reliabilities of the tests used to assess APD. Further research is indicated to explore additional factors, and consensus is needed to improve the reliability of tests or find alternative approaches to diagnose APD, based on the underlying factors. © 2014 by Lippincott Williams & Wilkins.

Blackman G.A.,MRC Institute of Hearing Research | Hall D.A.,MRC Institute of Hearing Research | Hall D.A.,NIHR National Biomedical Research Unit in Hearing
Journal of Speech, Language, and Hearing Research | Year: 2011

Purpose: The intense sound generated during functional magnetic resonance imaging (fMRI) complicates studies of speech and hearing. This experiment evaluated the benefits of using active noise cancellation (ANC), which attenuates the level of the scanner sound at the participant's ear by up to 35 dB around the peak at 600 Hz. Method: Speech and narrowband noise were presented at a low sound level to 8 listeners during fMRI using 2 common scanning protocols: short ("continuous") and long ("sparse") temporal schemes. Three outcome measures were acquired simultaneously during fMRI: ratings of listening quality, discrimination performance, and brain activity. Results: Subjective ratings and discrimination performance were significantly improved by ANC and sparse acquisition. Sparse acquisition was the more robust method for detecting auditory cortical activity. ANC reduced some of the "extra-auditory" activity that might be associated with the effort required for perceptual discrimination in a noisy environment and also offered small improvements for detecting activity within Heschl's gyrus and planum polare. Conclusions: For the scanning protocols evaluated here, the sparse temporal scheme was the more preferable for detecting sound-evoked activity. In addition, ANC ensures that listening difficulty is determined more by the chosen stimulus parameters and less by the adverse testing environment. © American Speech-Language-Hearing Association.

Stewart H.J.,MRC Institute of Hearing Research | Mcintosh R.D.,University of Edinburgh | Williams J.H.G.,University of Aberdeen
Autism Research | Year: 2013

Imitation is a potentially crucial aspect of social cognitive development. Although deficits in imitation ability have been widely demonstrated in autism spectrum disorder (ASD), the specificity and significance of the findings is unclear, due largely to methodological limitations. We developed a novel assessment of imitation ability, using objective movement parameters (path length and action duration) derived from a touch-sensitive tablet laptop during drawing actions on an identical tablet. By direct comparison of the kinematics of a model's actions with those of the participant who observed them, measures of imitation accuracy were obtained. By replaying the end-point of the movement as a spot on the screen, imitation accuracy was compared against a "ghost control" condition, with no human actor but only the end-point of the movement seen [object movement reenactment (OMR)]. Hence, demands of the control task were closely matched to the experimental task with respect to motor, memory, and attentional abilities. Adolescents with ASD showed poorer accuracy for copying object size and action duration on both the imitation and OMR tasks, but were significantly more impaired for imitation of object size. Our results provide evidence that some of the imitation deficit in ASD is specific to a self-other mapping problem, and cannot be explained by general factors such as memory, spatial reasoning, motor control, or attention, nor related to the social demands of the testing situation. © 2013 International Society for Autism Research, Wiley Periodicals, Inc.

Fullgrabe C.,MRC Institute of Hearing Research | Moore B.C.J.,University of Cambridge | Stone M.A.,University of Manchester | Stone M.A.,Central Manchester NHS Hospitals Foundation Trust
Frontiers in Aging Neuroscience | Year: 2015

Hearing loss with increasing age adversely affects the ability to understand speech, an effect that results partly from reduced audibility. The aims of this study were to establish whether aging reduces speech intelligibility for listeners with normal audiograms, and, if so, to assess the relative contributions of auditory temporal and cognitive processing. Twenty-one older normal-hearing (ONH; 60-79 years) participants with bilateral audiometric thresholds = 20 dB HL at 0.125-6 kHz were matched to nine young (YNH; 18-27 years) participants in terms of mean audiograms, years of education, and performance IQ. Measures included: (1) identification of consonants in quiet and in noise that was unmodulated or modulated at 5 or 80 Hz; (2) identification of sentences in quiet and in co-located or spatially separated two-talker babble; (3) detection of modulation of the temporal envelope (TE) at frequencies 5-180 Hz; (4) monaural and binaural sensitivity to temporal fine structure (TFS); (5) various cognitive tests. Speech identification was worse for ONH than YNH participants in all types of background. This deficit was not reflected in self-ratings of hearing ability. Modulation masking release (the improvement in speech identification obtained by amplitude modulating a noise background) and spatial masking release (the benefit obtained from spatially separating masker and target speech) were not affected by age. Sensitivity to TE and TFS was lower for ONH than YNH participants, and was correlated positively with speech-in-noise (SiN) identification. Many cognitive abilities were lower for ONH than YNH participants, and generally were correlated positively with SiN identification scores. The best predictors of the intelligibility of SiN were composite measures of cognition and TFS sensitivity. These results suggest that declines in speech perception in older persons are partly caused by cognitive and perceptual changes separate from age-related changes in audiometric sensitivity. © 2015 Füllgrabe, Moore and Stone.

de Boer J.,MRC Institute of Hearing Research | de Boer J.,MRC Institute of Hearing Research Southampton Section | Thornton A.R.D.,MRC Institute of Hearing Research Southampton Section | Krumbholz K.,MRC Institute of Hearing Research
Journal of Neurophysiology | Year: 2012

The medial olivocochlear (MOC) bundle reduces the gain of the cochlear amplifier through reflexive activation by sound. Physiological results indicate that MOC-induced reduction in cochlear gain can enhance the response to signals when presented in masking noise. Some previous studies suggest that this "antimasking" effect of the MOC system plays a role in speech-innoise perception. The present study set out to reinvestigate this hypothesis by correlating measures of MOC activity and speech-innoise processing across a group of normal-hearing participants. MOC activity was measured using contralateral suppression of otoacoustic emissions (OAEs), and speech-in-noise processing was measured by measuring the effect of noise masking on performance in a consonantvowel (CV) discrimination task and on auditory brain stem responses evoked by a CV syllable. Whereas there was a significant correlation between OAE suppression and both measures of speech-in-noise processing, the direction of this correlation was opposite to that predicted by the antimasking hypothesis, in that individuals with stronger OAE suppression tended to show greater noise-masking effects on CV processing. The current results indicate that reflexive MOC activation is not always beneficial to speech-in-noise processing. We propose an alternative to the antimasking hypothesis, whereby the MOC system benefits speech-in-noise processing through dynamic (e.g., attention-and experience-dependent), rather than reflexive, control of cochlear gain. © 2012 the American Physiological Society.

Lanting C.P.,MRC Institute of Hearing Research | Briley P.M.,MRC Institute of Hearing Research | Briley P.M.,University of York | Sumner C.J.,MRC Institute of Hearing Research | Krumbholz K.,MRC Institute of Hearing Research
Journal of Neurophysiology | Year: 2013

This study investigates the temporal properties of adaptation in the late auditory-evoked potentials in humans. The results are used to make inferences about the mechanisms of adaptation in human auditory cortex. The first experiment measured adaptation by single adapters as a combined function of the adapter duration and the stimulus onset asynchrony (SOA) and interstimulus interval (ISI) between the adapter and the adapted sound ("probe"). The results showed recovery from adaptation with increasing ISI, as would be expected, but buildup of adaptation with increasing adapter duration and thus SOA. This suggests that adaptation in auditory cortex is caused by the ongoing, rather than the onset, response to the adapter. Quantitative modeling indicated that the rate of buildup of adaptation is almost an order of magnitude faster than the recovery rate of adaptation. The recovery rate suggests that cortical adaptation is caused by synaptic depression and slow afterhyperpolarization. The P2 was more strongly affected by adaptation than the N1, suggesting that the two deflections originate from different cortical generators. In the second experiment, the single adapters were replaced by trains of two or four identical adapters. The results indicated that adaptation decays faster after repeated presentation of the adapter. This increase in the recovery rate of adaptation might contribute to the elicitation of the auditory mismatch negativity response. It may be caused by top-down feedback or by local processes such as the buildup of residual Ca2+ within presynaptic neurons. © 2013 the American Physiological Society.

Nuttall H.E.,MRC Institute of Hearing Research
Proceedings of Meetings on Acoustics | Year: 2013

In background noise, the timing precision of the auditory brainstem response to speech (speech-ABR) is disrupted and the response latency increases. The severity of the disruption has been correlated with listeners' ability to understand speech-in-noise. To date, although a central mechanism is assumed, the locus of the speech-ABR timing disruption is not clear. The present study aimed to investigate the contribution of different cochlear mechanisms to noise-induced latency increases. A first experiment examined the 'cochlear place' mechanism, by which the latency of the response increases as cochlear origin moves towards lower frequency regions. The results showed that the speech-ABR reflects an average over responses from a broad range of cochlear regions, which respond with substantial relative delays. This implies that cochlear place can potentially have large effects on masked speech-ABR latency. Another mechanism that is known to be involved in noise-induced ABR latency increases is neural adaptation. This is presumed to occur at the inner hair cell-nerve junction and is thought to reflect cochlear masking. Thus, if this mechanism contributes to speech-ABR latency increases in noise, we would expect this contribution to depend on cochlear frequency selectivity and amplification gain. This hypothesis is tested in the second experiment. © 2013 Acoustical Society of America.

Banai K.,Haifa University | Amitay S.,MRC Institute of Hearing Research
Vision Research | Year: 2012

Stimulus uncertainty produced by variations in a target stimulus to be detected or discriminated, impedes perceptual learning under some, but not all experimental conditions. To account for those discrepancies, it has been proposed that uncertainty is detrimental to learning when the interleaved stimuli or tasks are similar to each other but not when they are sufficiently distinct, or when it obstructs the downstream search required to gain access to fine-grained sensory information, as suggested by the Reverse Hierarchy Theory (RHT). The focus of the current review is on the effects of uncertainty on the perceptual learning of speech and non-speech auditory signals. Taken together, the findings from the auditory modality suggest that in addition to the accounts already described, uncertainty may contribute to learning when categorization of stimuli to phonological or acoustic categories is involved. Therefore, it appears that the differences reported between the learning of non-speech and speech-related parameters are not an outcome of inherent differences between those two domains, but rather due to the nature of the tasks often associated with those different stimuli. © 2012 Elsevier Ltd.

Agency: GTR | Branch: BBSRC | Program: | Phase: Research Grant | Award Amount: 151.86K | Year: 2013

Conversation is crucial to many everyday activities, and most people have no difficulties engaging in one, at least not when they are young, the background is quiet and their hearing is good. However, as people get older, they can find it increasingly difficult to carry on a conversation, particularly if it is taking place in a background of noise. This is true even when they have no clinically significant hearing loss. The fact that difficulties of speech perception in noise tend to be unrelated to age-related loss in hearing sensitivity is further highlighted by the fact that hearing aids have proven rather ineffective at alleviating these particular communication challenges thus leaving older listeners at the risk of frustration and social withdrawal. Many studies have documented age-related changes for speech perception in noise, either by reporting the percentage of older listeners who show these difficulties or by using objective measures to quantify these difficulties in older adults, compared to young adults. Moreover, work carried out by members of this group has demonstrated that noisy environments have adverse effects on communication that occur in addition to the comprehension difficulties often stated as the main problem. For instance, older adults show memory deficits for correctly perceived speech which are specific to noisy environments, and which are not being identified or appreciated by current standard audiometric or psychophysical speech perception measures. Although many studies have tried to understand why these difficulties in noise occur, and why they are, for the most part, unrelated to hearing loss treatable with hearing aids, there are currently no effective treatments available to alleviate these problems. Most studies to date examine the question from one vantage point only, be that psychology, audiology, neuroscience or social sciences. The current project is the first of its kind that takes a broad integrative approach and combines knowledge and expertise of all of these disciplines to develop a fuller and more complete picture of the situation and its underlying causes. In the course of the project, we will be seeking answers to questions such as: Which environmental situations do older adults perceive as most disruptive to communication, and how do these situations restrict older adults mobility and participation in society? What are useful objective measures of environmental noise sources important in the context of communication? Which voice characteristics drive the age difference in disruptiveness of background voices? How does attentional decline interact with auditory decline in aging? Do different individual trajectories of auditory and cognitive declines lead to different age-related deficits? Moreover, given our increasingly multi-cultural world in which many seniors and care-providers must function in a second-language environment, how do various native and non-native speech accents affect communication in old age? In addition to trying to uncover potential causes for the observed difficulties, this study also aims to take the research one step further and convert our knowledge about various causes of speech comprehension difficulties into support and remediation for older adults by proposing and testing potential coping strategies that aim to alleviate the demonstrated difficulties. These strategies may include architectural recommendations to reduce noise in public places, listening training procedures or the active shaping of noise environments. This project brings together expertise and knowledge of researchers from the UK, Finland, Israel and Canada in order to tackle communication difficulties faced by most older adults and to offer suggestions for coping strategies that will ultimately benefit older adults social integration and life satisfaction.

Agency: GTR | Branch: MRC | Program: | Phase: Intramural | Award Amount: 243.31K | Year: 2015

Many people have a hearing loss, especially if they are older adults. Question is, if a person has a hearing loss now, how accurately can we predict how much worse their hearing loss will get in the future? How well can we predict who of those people who do not have a hearing loss will stay that way? Some children are diagnosed with Auditory Processing Disorder – how does that progress? Does it continue, deteriorate, or even recover as people age? The purpose of the research in this programme is to develop the science to answer some of these questions. As well as giving important new science, the research will be of assistance in measuring the effectiveness of hearing screening programs, as well as perhaps helping to predict who will gain benefit from any innovative new treatments that result from future discoveries in the biomedical science of hearing.

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