Auditory verbal working memory as a predictor of speech perception in modulated maskers in normal-hearing listeners

Purpose: Background noise can interfere with our ability to understand speech. Working memory capacity (WMC) has been shown to contribute to the perception of speech in modulated noise maskers. WMC has been assessed with a variety of auditory and visual tests, often pertaining to different components of working memory. This study assessed the relationship between speech perception in modulated maskers and components of auditory verbal working memory (AVWM) over a range of signal-to-noise ratios. Method: Speech perception in noise and AVWM were measured in 30 listeners (age range 31-67 years) with normal hearing. AVWM was estimated using forward digit recall, backward digit recall, and non-word repetition. Results: After controlling for the effects of age and average pure-tone hearing threshold, speech perception in modulated maskers was related to individual differences in the phonological component of working memory (as assessed by non-word repetition) but only in the least favorable SNR. The executive component of working memory (as assessed by backward digit) was not predictive of speech perception in any conditions. Conclusions: AVWM is predictive of the ability to benefit from temporal dips in modulated maskers: Listeners with greater phonological WMC are better able to correctly identify sentences in modulated noise backgrounds

Auditory Verbal Working Memory as a Predictor of Speech Perception in Modulated Maskers in Listeners With Normal Hearing

Purpose Background noise can interfere with our ability to understand speech. Working memory capacity (WMC) has been shown to contribute to the perception of speech in modulated noise maskers. WMC has been assessed with a variety of auditory and visual tests, often pertaining to different components of working memory. This study assessed the relationship between speech perception in modulated maskers and components of auditory verbal working memory (AVWM) over a range of signal-to-noise ratios. Method Speech perception in noise and AVWM were measured in 30 listeners (age range 31–67 years) with normal hearing. AVWM was estimated using forward digit recall, backward digit recall, and nonword repetition. Results After controlling for the effects of age and average pure-tone hearing threshold, speech perception in modulated maskers was related to individual differences in the phonological component of working memory (as assessed by nonword repetition) but only in the least favorable signal-to-noise ratio. The executive component of working memory (as assessed by backward digit) was not predictive of speech perception in any conditions. Conclusions AVWM is predictive of the ability to benefit from temporal dips in modulated maskers: Listeners with greater phonological WMC are better able to correctly identify sentences in modulated noise backgrounds. </jats:sec

Improving the provision of hearing care to long-term care home residents with dementia: developing a behaviour change intervention for care staff

Context: Hearing loss disproportionately affects long-term care home (LTCH) residents with dementia, impacting their quality of life. Most residents with dementia rely on LTCH staff to provide hearing care. However, previous research shows provision is inconsistent. The Behaviour Change Wheel (BCW) can be used for developing behaviour-change interventions. Objective: To describe the structured, multistage development of an intervention to help LTCH staff provide hearing care to residents with dementia. Method: Using results from qualitative and quantitative studies and patient and public involvement sessions, we outlined problems associated with hearing care and determined the changes that should be made using the Capabilities, Opportunities, and Motivation-Behaviour Change Model. We then selected and specified five target behaviours for intervention, and identified relevant intervention functions, behaviour change techniques (BCTs), and modes of delivery. Findings: The multi-component intervention is designed to boost the psychological capability, reflective motivation, and physical opportunity of care assistants. The intervention functions deemed most appropriate were education, modelling, incentivisation, and environmental restructuring, alongside several specific BCTs. Limitations: Some of the larger-scale issues relating to hearing care, such as collaborations between LTCHs and audiology services and the costs of hearing devices, were not able to be addressed in this intervention. Conclusions: This study is the first to use the BCW to develop an intervention targeting the staff’s provision of hearing care to LTCH residents with dementia. This intervention addresses the wide-ranging barriers that staff experience when providing hearing care. Trialling this intervention will provide insight into its effectiveness and acceptability for residents and staff

Divergent effects of listening demands and evaluative threat on listening effort in online and laboratory settings

ObjectiveListening effort (LE) varies as a function of listening demands, motivation and resource availability, among other things. Motivation is posited to have a greater influence on listening effort under high, compared to low, listening demands.MethodsTo test this prediction, we manipulated the listening demands of a speech recognition task using tone vocoders to create moderate and high listening demand conditions. We manipulated motivation using evaluative threat, i.e., informing participants that they must reach a particular “score” for their results to be usable. Resource availability was assessed by means of working memory span and included as a fixed effects predictor. Outcome measures were indices of LE, including reaction times (RTs), self-rated work and self-rated tiredness, in addition to task performance (correct response rates). Given the recent popularity of online studies, we also wanted to examine the effect of experimental context (online vs. laboratory) on the efficacy of manipulations of listening demands and motivation. We carried out two highly similar experiments with two groups of 37 young adults, a laboratory experiment and an online experiment. To make listening demands comparable between the two studies, vocoder settings had to differ. All results were analysed using linear mixed models.ResultsResults showed that under laboratory conditions, listening demands affected all outcomes, with significantly lower correct response rates, slower RTs and greater self-rated work with higher listening demands. In the online study, listening demands only affected RTs. In addition, motivation affected self-rated work. Resource availability was only a significant predictor for RTs in the online study.DiscussionThese results show that the influence of motivation and listening demands on LE depends on the type of outcome measures used and the experimental context. It may also depend on the exact vocoder settings. A controlled laboratory settings and/or particular vocoder settings may be necessary to observe all expected effects of listening demands and motivation

Binaural summation of amplitude modulation involves weak interaural suppression

The brain combines sounds from the two ears, but what is the algorithm used to achieve this summation of signals? Here we combine psychophysical amplitude modulation discrimination and steady-state electroencephalography (EEG) data to investigate the architecture of binaural combination for amplitude-modulated tones. Discrimination thresholds followed a ‘dipper’ shaped function of pedestal modulation depth, and were consistently lower for binaural than monaural presentation of modulated tones. The EEG responses were greater for binaural than monaural presentation of modulated tones, and when a masker was presented to one ear, it produced only weak suppression of the response to a signal presented to the other ear. Both data sets were well-fit by a computational model originally derived for visual signal combination, but with suppression between the two channels (ears) being much weaker than in binocular vision. We suggest that the distinct ecological constraints on vision and hearing can explain this difference, if it is assumed that the brain avoids over-representing sensory signals originating from a single object. These findings position our understanding of binaural summation in a broader context of work on sensory signal combination in the brain, and delineate the similarities and differences between vision and hearing

Magnified neural envelope coding predicts deficits in speech perception in noise

Verbal communication in noisy backgrounds is challenging. Understanding speech in background noise that fluctuates in intensity over time is particularly difficult for hearing-impaired listeners with a sensorineural hearing loss (SNHL). The reduction in fast-acting cochlear compression associated with SNHL exaggerates the perceived fluctuations in intensity in amplitude-modulated sounds. SNHL-induced changes in the coding of amplitude-modulated sounds may have a detrimental effect on the ability of SNHL listeners to understand speech in the presence of modulated background noise. To date, direct evidence for a link between magnified envelope coding and deficits in speech identification in modulated noise has been absent. Here, magnetoencephalography was used to quantify the effects of SNHL on phase locking to the temporal envelope of modulated noise (envelope coding) in human auditory cortex. Our results show that SNHL enhances the amplitude of envelope coding in posteromedial auditory cortex, whereas it enhances the fidelity of envelope coding in posteromedial and posterolateral auditory cortex. This dissociation was more evident in the right hemisphere, demonstrating functional lateralization in enhanced envelope coding in SNHL listeners. However, enhanced envelope coding was not perceptually beneficial. Our results also show that both hearing thresholds and, to a lesser extent, magnified cortical envelope coding in left posteromedial auditory cortex predict speech identification in modulated background noise. We propose a framework in which magnified envelope coding in posteromedial auditory cortex disrupts the segregation of speech from background noise, leading to deficits in speech perception in modulated background noise

Dynamic semantic cognition : Characterising coherent and controlled conceptual retrieval through time using magnetoencephalography and chronometric transcranial magnetic stimulation

Distinct neural processes are thought to support the retrieval of semantic information that is (i) coherent with strongly-encoded aspects of knowledge, and (ii) non-dominant yet relevant for the current task or context. While the brain regions that support readily coherent and more controlled patterns of semantic retrieval are relatively well-characterised, the temporal dynamics of these processes are not well-understood. This study used magnetoencephalography (MEG) and dual-pulse chronometric transcranial magnetic stimulation (cTMS) in two separate experiments to examine temporal dynamics during the retrieval of strong and weak associations. MEG results revealed a dissociation within left temporal cortex: anterior temporal lobe (ATL) showed greater oscillatory response for strong than weak associations, while posterior middle temporal gyrus (pMTG) showed the reverse pattern. Left inferior frontal gyrus (IFG), a site associated with semantic control and retrieval, showed both patterns at different time points. In the cTMS experiment, stimulation of ATL at ∼150 msec disrupted the efficient retrieval of strong associations, indicating a necessary role for ATL in coherent conceptual activations. Stimulation of pMTG at the onset of the second word disrupted the retrieval of weak associations, suggesting this site may maintain information about semantic context from the first word, allowing efficient engagement of semantic control. Together these studies provide converging evidence for a functional dissociation within the temporal lobe, across both tasks and time

Pain management in the neonatal piglet during routine management procedures. Part 2:Grading the quality of evidence and the strength of recommendations

Piglets reared in swine production in the USA undergo painful procedures that include castration, tail docking, teeth clipping, and identification with ear notching or tagging. These procedures are usually performed without pain mitigation. The objective of this project was to develop recommendations for pain mitigation in 1- to 28-day-old piglets undergoing these procedures. The National Pork Board funded project to develop recommendations for pain mitigation in piglets. Recommendation development followed a defined multi-step process that included an evidence summary and estimates of the efficacies of interventions. The results of a systematic review of the interventions were reported in a companion paper. This manuscript describes the recommendation development process and the final recommendations. Recommendations were developed for three interventions (CO2/O2 general anesthesia, non-steroidal anti-inflammatory drugs (NSAIDs), and lidocaine) for use during castration. The ability to make strong recommendations was limited by low-quality evidence and strong certainty about variation in stakeholder values and preferences. The panel strongly recommended against the use of a CO2/O2 general anesthesia mixture, weakly recommended for the use of NSAIDs and weakly recommended against the use of lidocaine for pain mitigation during castration of 1- to 28-day-old piglets

Effects of noise exposure on young adults with normal audiograms II: Behavioral measures

An estimate of lifetime noise exposure was used as the primary predictor of performance on a range of behavioral tasks: frequency and intensity difference limens, amplitude modulation detection, interaural phase discrimination, the digit triplet speech test, the co-ordinate response speech measure, an auditory localization task, a musical consonance task and a subjective report of hearing ability. One hundred and thirty-eight participants (81 females) aged 18–36 years were tested, with a wide range of self-reported noise exposure. All had normal pure-tone audiograms up to 8 kHz. It was predicted that increased lifetime noise exposure, which we assume to be concordant with noise-induced cochlear synaptopathy, would elevate behavioral thresholds, in particular for stimuli with high levels in a high spectral region. However, the results showed little effect of noise exposure on performance. There were a number of weak relations with noise exposure across the test battery, although many of these were in the opposite direction to the predictions, and none were statistically significant after correction for multiple comparisons. There were also no strong correlations between electrophysiological measures of synaptopathy published previously and the behavioral measures reported here. Consistent with our previous electrophysiological results, the present results provide no evidence that noise exposure is related to significant perceptual deficits in young listeners with normal audiometric hearing. It is possible that the effects of noise-induced cochlear synaptopathy are only measurable in humans with extreme noise exposures, and that these effects always co-occur with a loss of audiometric sensitivity