Attended Ear Research Articles

Cochleostomy and facial recess packing alter cochlear implant electrode location in a human cochlea model

PurposeDetermine the effect of cochleostomy and facial recess packing on cochlear implant electrode distance from the modiolus. Materials and methodsTwo otolaryngology residents (PGY5 and PGY6) and one attending ear surgeon performed electrode insertions on a human cochlea model using perimodiolar (Cochlear® Slim Modiolar 532™, CI532) and lateral wall electrodes (Cochlear® Slim Straight 522™, CI522) via a cochleostomy. Packing material was simulated using cotton and placed in the cochleostomy and facial recess under the following conditions: 1) inferior to the electrode, 2) superior, 3) both inferior and superior, and 4) no packing. Distance of the electrode from the modiolus at the proximal, middle, and distal basal turn of the cochlea were measured by photomicrograph analysis. ResultsPacking superior to the CI532 resulted in a significant decrease in distance from the modiolus at the middle and distal basal turn compared to the inferior condition, with the largest effect in the middle basal turn (0.25 mm vs. 1.92 mm, respectively, p < 0.001). For the CI522, packing superior similarly resulted in decreased distance to the modiolus when compared to the inferior packing condition at the middle and distal basal turn regions, with the largest effect in the middle basal turn (1.25 mm vs. 1.75 mm, respectively, p = 0.002). ConclusionsPacking of the cochleostomy site and facial recess has a significant effect on electrode distance from the modiolus in the middle and distal basal turn using a model of a human cochlea. Effects were more pronounced when using the perimodiolar (CI532) electrode.

Bacteriological Profile and Antimicrobial Susceptibility Pattern in Chronic Suppurative Otitis Media: A 1-Year Cross-Sectional Study.

Inadequate antibiotic treatment, misuse/improper choice of antibiotic and poor compliance of patients have resulted in changes in susceptibility to antibiotics of the causative organisms and also development of resistance to commonly used antibiotics. Thus, this study aimed to identify the bacteriological profile and determine antibiotic susceptibility pattern in CSOM patients. This 1-year cross-sectional study was conducted on 120 clinically diagnosed cases of CSOM attending ear, nose, and throat outpatient department. Ear discharges obtained were processed for bacterial culture (aerobic and anaerobic). Antimicrobial susceptibility testing was done by Kirby-Bauer disc diffusion method. Demographic and clinical characteristics of the patients were recorded. Of total 120 cases, pathogens were isolated from 116 cases. The commonest aerobic organism isolated was Pseudomonas aeruginosa (38.79%) followed by Staphylococcus aureus (32.75%). Staphylococcus aureus showed maximum sensitivity to erythromycin (71.05%), followed by cotrimoxazole (63.15%) and ampicillin (55.26%). Maximum resistance was observed for ciprofloxacin (78.9%), followed by amoxiclave (55.26%). Pseudomonas aeruginosa showed maximum sensitivity to piperacillin (91.11%) followed by gentamicin (71.11%), amikacin (71.11%), moderate sensitivity to ceftazidime (51.11%); however resistance to carbpenicillin (60%). Ciprofloxacin was the most prescribed topical agent showing an increase in resistance to common organisms of CSOM. Hence, it is mandatory to study each case of CSOM bacteriologically to formulate local antibiotic policy for appropriate use of antibiotics. This will certainly help in achieving a safe ear and to control the organisms developing resistance to prevalent antibiotics.

On the locus of talker-specificity effects in spoken word recognition: an ERP study with dichotic priming

ABSTRACTWe used event-related potentials to examine the precise moment at which talker-specific information comes into play during spoken word recognition. Dichotic repetition priming was examined with primes presented in the left unattended ear and targets presented in the right attended ear, and we manipulated both word frequency and talker identity. A clear repetition priming effect was observed in an early time-window spanning 100–200 ms post-target onset, and the effect continued after target word offset in a time-window between 650 and 800 ms. Crucially, we observed that talker change caused a diminution in repetition priming only in the N400 time-window, and only for low frequency words but not for high frequency words. Together, our findings suggest that spoken word recognition relies primarily on abstract representations, and that talker-specific information mainly affects later stages of this process, namely lexical selection.

The effect of head-related filtering and ear-specific decoding bias on auditory attention detection**This research work was carried out at the ESAT and ExpORL Laboratories of KU Leuven, in the frame of KU Leuven Special Research Fund BOF/STG-14-005, OT/14/119 and C14/16/057. The work has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation

Objective. We consider the problem of Auditory Attention Detection (AAD), where the goal is to detect which speaker a person is attending to, in a multi-speaker environment, based on neural activity. This work aims to analyze the influence of head-related filtering and ear-specific decoding on the performance of an AAD algorithm. Approach. We recorded high-density EEG of 16 normal-hearing subjects as they listened to two speech streams while tasked to attend to the speaker in either their left or right ear. The attended ear was switched between trials. The speech stimuli were administered either dichotically, or after filtering using Head-Related Transfer Functions (HRTFs). A spatio-temporal decoder was trained and used to reconstruct the attended stimulus envelope, and the correlations between the reconstructed and the original stimulus envelopes were used to perform AAD, and arrive at a percentage correct score over all trials. Main results. We found that the HRTF condition resulted in significantly higher AAD performance than the dichotic condition. However, speech intelligibility, measured under the same set of conditions, was lower for the HRTF filtered stimuli. We also found that decoders trained and tested for a specific attended ear performed better, compared to decoders trained and tested for both left and right attended ear simultaneously. In the context of the decoders supporting hearing prostheses, the former approach is less realistic, and studies in which each subject always had to attend to the same ear may find over-optimistic results. Significance. This work shows the importance of using realistic binaural listening conditions and training on a balanced set of experimental conditions to obtain results that are more representative for the true AAD performance in practical applications.

Effectiveness of nurse-led clinics on service delivery and clinical outcomes in adults with chronic ear, nose and throat complaints

Ear, nose and throat complaints are very common and can cause significant disruption to patients' lives. Many conditions are of a chronic nature and are not currently managed in a timely manner by general practitioners in the community. This may be due to a lack of specialized knowledge, necessary diagnostic equipment or time for lengthy patient education on management of their condition. A nurse-led model of care may be an effective alternative. To examine the effectiveness of nurse-led clinics on adults with chronic ear, nose and throat complaints. Adult patients, aged 18 years and older, attending ear, nose and throat clinics, regardless of the complaint. Nurse-led care in general practice and acute care in which the nurse was identified as taking a lead role in the care of the patients with chronic ear, nose and throat complaints. General practitioner-led care, or ear, nose and throat consultant-led care, sometimes described as "standard care". Service delivery outcomes, clinical and health outcomes and financial outcomes. Any relevant quantitative studies published in English between 1980 and 2013 were considered. A standardized three-step search strategy aimed to find both published and unpublished studies. Databases searched include PubMed, CINAHL, Cochrane Library (CENTRAL), Scopus, Embase, MedNar and ProQuest Theses and Dissertations. Methodological validity was assessed independently by two reviewers using standardized critical appraisal instruments from the Joanna Briggs Institute. Due to methodological heterogeneity of the included studies, no statistical pooling was possible and all results are presented narratively. The search identified 13,536 titles, of which 20 potentially relevant articles were retrieved. Of these 20, 17 were excluded following full-text review leaving three studies that were assessed for methodological quality and included in the review. Service delivery outcome findings were that patient satisfaction was equal or higher and waiting times were shorter in nurse led clinics. The other service delivery outcomes were not addressed. Clinical and health outcomes findings were that lower pain/discomfort levels were demonstrated in nurse led clinics but other clinical/health outcomes were not addressed. Financial outcomes findings were that nurse-led clinics were cost effective when compared with medical-led clinics. While all studies reported evidence of the effectiveness of nurse-led clinics in service delivery and clinical outcomes in adults with chronic ear, nose and throat complaints, most of the data was self-reported and many of the outcomes of interest were not considered. The lack of experimental trials means that the level of evidence is low and further research is needed. There was also not enough detail in the financial outcomes from which clear conclusions of the cost benefit of nurse-led clinics could be drawn. Evidence from included studies indicated higher levels of patient satisfaction, cost benefits and lower levels of pain/discomfort in nurse-led clinics, which suggests that nurse-led ear, nose and throat clinics may be considered in the management of adult patients with ear, nose and throat complaints. Currently there is little evidence examining the effectiveness of nurse-led ear, nose and throat clinics. Areas to be addressed by future research should include: levels of patient education, booking queues, levels of self-treatment change in presentation to clinic episodes, reinfection rates, prevention and cure and representation of patients at clinics for same complaint.

An ERP investigation of dichotic repetition priming with temporally overlapping stimuli.

In the present study, we used event-related potentials (ERPs) to examine the effects of prime-target repetition using a dichotic priming paradigm. Participants monitored a stream of target words in the right, attended ear for occasional animal names, and ERPs were recorded to nonanimal words that were either unrelated to or a repetition of prime words presented to the left ear. The prime words were spoken in a different voice and had a lower intensity than did the target words, and the prime word onset occurred 50 ms before target word onset. Repetition-priming effects were observed in the ERPs starting around 150 ms post-target-onset and continued to influence processing for the duration of the target stimuli. These priming effects provide further evidence in favor of parallel processing of overlapping dichotic stimuli, at least up to the level of some form of sublexical phonological representation, a likely locus for the integration of the two sources of information.

Improving emotional prosody detection in the attending ear by cathodal tDCS suppression of the competing channel

Currently it is assumed that cathodal stimulation (in transcranial direct current stimulation, tDCS) degrades the neural firing rate, and thus it is believed to degrade cognitive performance. Here we challenge this assumption by predicting that under high competition the cathodal stimulation might act as a noise filter, leading to an improved performance. We presented auditory targets with different emotional valence using a dichotic listening paradigm. We found that cathodal, but not anodal stimulation of the right IFG generated better prosody comprehension. Cathodal stimulation in competitive situations, such as the dichotic listening paradigm, can act like a noise filter, and may in fact enhance cognitive performance. This study contributes to understanding the way the IFG is engaged with prosody functions, and explains the cathodal effects of tDCS. This might lead to the development of more efficient brain stimulation protocols.

Attention-driven auditory cortex short-term plasticity helps segregate relevant sounds from noise

How can we concentrate on relevant sounds in noisy environments? A "gain model" suggests that auditory attention simply amplifies relevant and suppresses irrelevant afferent inputs. However, it is unclear whether this suffices when attended and ignored features overlap to stimulate the same neuronal receptive fields. A "tuning model" suggests that, in addition to gain, attention modulates feature selectivity of auditory neurons. We recorded magnetoencephalography, EEG, and functional MRI (fMRI) while subjects attended to tones delivered to one ear and ignored opposite-ear inputs. The attended ear was switched every 30 s to quantify how quickly the effects evolve. To produce overlapping inputs, the tones were presented alone vs. during white-noise masking notch-filtered ±1/6 octaves around the tone center frequencies. Amplitude modulation (39 vs. 41 Hz in opposite ears) was applied for "frequency tagging" of attention effects on maskers. Noise masking reduced early (50-150 ms; N1) auditory responses to unattended tones. In support of the tuning model, selective attention canceled out this attenuating effect but did not modulate the gain of 50-150 ms activity to nonmasked tones or steady-state responses to the maskers themselves. These tuning effects originated at nonprimary auditory cortices, purportedly occupied by neurons that, without attention, have wider frequency tuning than ±1/6 octaves. The attentional tuning evolved rapidly, during the first few seconds after attention switching, and correlated with behavioral discrimination performance. In conclusion, a simple gain model alone cannot explain auditory selective attention. In nonprimary auditory cortices, attention-driven short-term plasticity retunes neurons to segregate relevant sounds from noise.

Elastic attention: enhanced, then sharpened response to auditory input as attentional load increases

A long debate in selective attention research is whether attention enhances sensory response or sharpens neural tuning by suppressing response to non-target input. In fact, both processes may occur as a function of load: an uncertain listener might use a broad attentional filter to enhance responses to all inputs (i.e., vigilance), yet employ sharpened tuning to focus on hard to discriminate targets. The present work used the greater signal gain, anatomical precision, and laterality separation of intracranial electrophysiological recordings (electrocorticograms) to investigate these competing effects. Data were recorded from acoustically-responsive cortex in the perisylvian region of a single hemisphere in five neurosurgery patients. Patients performed a dichotic listening task in which they alternately attended toward, away from, or completely ignored (silent reading) tones presented to designated ears at varying presentation rates. Comparisons between the grand-averaged event-related potential (ERP) waveforms show a striking change in the effect of selective auditory attention with attentional load. At slower presentation rates (low-load), ERPs were overall enhanced in response to both input channels and regardless of attended ear, including a significant enhancement of ipsilateral input. This result supports a broadly enhancing model of attention under low perceptual load conditions. At the fastest rate, however, only responses to attended inputs contralateral to grid location remained enhanced. This result supports an increasing suppression, or “sharpening,” of neural responses to non-targets with increasing attentional load. These data provide support for an elastic model of attention in which attentional scope narrows with increasing load.

Activations of Human Auditory Cortex During Visual and Auditory Selective Attention Tasks with Varying Difficulty

The present study was designed to directly test the hypothesis that suppression of activations to task-irrelevant sounds contributes to the attention-related modulations of auditory cortex (AC) activations observed in previous fMRI studies. Subjects selectively attended to auditory (broadband noise bursts with pitch) or visual (Gabor gratings) asynchronous fast-rate stimulus streams concurrently presented to left-ear, right-ear, above-fixation, or below-fixation. Auditory and visual task difficulty was parametrically manipulated in three levels. Behavioral data obtained during fMRI indicated that subjects achieved acceptable performance levels in all tasks and that the task-difficulty manipulation was effective. Consistent with previous studies, AC activations strongly depended on the direction of attention. AC activations to sounds were higher during auditory than during visual tasks and AC activations were higher in the hemisphere contralateral to the attended ear. However, the effects of task difficulty on AC activations were weak or non-existent. In particular, increasing task difficulty was not associated with a systematic decrease of AC activations in areas that were modulated by attention. These results suggest that suppression of AC activations to task-irrelevant sounds is likely to be small or negligible as compared with the strong activation enhancements observed in fMRI during active auditory tasks.

Auditory biases in attention by hunger state: A preliminary study

Research has demonstrated that both memory and attention are important cognitive factors in the control of eating behaviour. In the case of attention this has been demonstrated with mainly visual attentional tasks such as the modified Stroop and dot-probe. However, it is also the case that attention is driven by the filtering out of information as well as its prioritisation. This preliminary study aimed to examine this issue using a novel Dichotic Listening Task (DLT), to see whether auditory biases in attention were apparent in different hunger states. Two groups of individuals ( n =10 per group) who differed in subjective ratings of hunger (High/Low) completed the DLT, where sections of a prose passage to the attended ear were each accompanied by a food or non-food word to the unattended ear. Results demonstrated a significant Word×Hunger state interaction where individuals in a high versus low hunger state reported more food compared to control words with the reverse pattern found for those in the low hunger state. This suggests that for those in a high but not low hunger state, food versus control words received greater attention and confirms the ability of the DLT to detect such effects

Subcortical white matter pathology as a mediating factor for age-related decreased performance in dichotic listening

Cortical ‘disconnection’, involving disruption of white matter tracts in the brain, has been hypothesized as a mechanism of age-related cognitive decline. Diffuse hyperintensities in the white matter (so called white matter hyperintensities, WMH) on T2-weighted MRI scans are regarded to represent ischemic damage of the subcortical fiber system and are found to be increased with advanced age. In the present study, we examined whether WMH might be a mediating factor for age-effects in dichotic listening. For that purpose, we examined the association between age, deep or subcortical white matter hyperintensities (DWMH), periventricular hyperintensities (PVH) and dichotic listening performance in healthy older adults with ages ranging from 50 to 81 years. We found decreased dichotic listening performance with increasing age, specifically for the left ear (LE) but not the right ear (RE) in a standard unbiased-attention condition, and for the unattended ears but not the attended ears in conditions in which attention was controlled. Interestingly, hierarchical regression analyses revealed that the age-effect is partially mediated by DWMH specifically in the hemisphere contralateral to the attended ear. Moreover, we found indications that RE performance is specifically affected by DWMH in the right and left frontal and temporal areas, and that LE performance is mostly affected by DWMH selectively in the left hemisphere, including the left temporal area. The present study underlines the idea that disconnectivity is involved in age-related cognitive decline.

Material type and attention control in dichotic listening

The present study investigated the effects of semantic and emotional content on laterality effects found in focused attention dichotic listening tasks. A total of 80 right-handed participants completed one of four conditions. They were presented either with dichotic pairs of consonant-vowel (CV) syllables (ba, da, ga, ka, pa, or ta) or words (bower, dower, power, or tower), pronounced in either a neutral tone or one of four emotional tones (happy, sad, angry, neutral). In all conditions, participants were instructed to circle the stimulus presented to the attended ear on each trial. The attended ear was randomised between blocks of trials for each participant. A significant condition by ear attended by ear of presentation interaction emerged. The typical right ear advantage (REA) was found in the neutral conditions, regardless of ear attended. In contrast, the emotional conditions revealed an REA when participants focused on the right ear, whereas a left ear advantage was found when they focused on the left ear. These findings suggest that the emotional component resulted in a shift in ear advantage coinciding with instructions possibly because of the influence of this component on attention and task difficulty. The role of semantic processing in words versus syllables is also discussed.

Brain electric activity for active inhibition of auditory irrelevant information

We applied high resolution event-related potentials (ERPs) to assess brain activities associated with inhibition of irrelevant information processing during auditory selective attention. Ten healthy subjects performed an auditory selective attention task. ERPs in response to standard stimuli delivered to the unattended ear (irrelevant stimuli) and those delivered to the attended ear (relevant stimuli) were evaluated using temporally sequential scalp current density (SCD) mappings. For the irrelevant stimuli, current sources were located in the mid-frontal regions at 140–220 ms post-stimuli, and these SCD values were significantly larger than those for the relevant stimuli. These results suggest that auditory selective attention process involves not only focusing attention on relevant information, but also inhibitory processing of irrelevant information mediated by the frontal cortex.

Chronic Worry as Avoidance of Arousal

Previous research suggests that worry is primarily a verbal-linguistic activity that may serve as a method of cognitive avoidance of fearful imagery. The purpose of the present study was to examine cognitive avoidance in high worriers (N=22) and low worriers (N=24) using psychophysiological measures and a modified dichotic listening task. The task involved presenting neutral words into an unattending ear while worry or neutral scenarios were presented into the attending ear. Participants were given a surprise word recognition test of the words presented to provide evidence of cognitive avoidance beyond self-report. Contrary to the hypotheses, high worriers did not have less physiological reactivity than did low worriers. Low worriers recognized more words than did high worriers overall. High worriers remembered more words from the worry scenario than the neutral condition, as would be expected if they attempted to avoid the worry scenario. Implications for treatment of worry and the use of the dichotic listening task in researching worry are discussed.

Functional Anatomy of Human Auditory Attention Studied with PET

Positron emission tomography was used to investigate the functional anatomy of selective auditory attention in 17 right-handed male volunteers who submitted to different tasks: silent rest (REST), listening to frequent low- or rare high-pitched tones (LIS) delivered randomly to the right or the left ear, selective auditory attention where subjects had to attend to deviants in one ear, right (ATTR) or left (ATTL). Six subjects had the series REST, LIS, ATTR twice, eight subjects the series REST, LIS, ATTL, and the last three subjects the series REST, ATTR, ATTL. Event-related potentials were simultaneously recorded with PET and showed significant task and electrode site effects on the N100 amplitude. When compared to REST, LIS elicited bilateral temporal activations of the Heschl's gyri and theplanum temporale,with a significant rightward asymmetry, and of the posterior part of the superior temporal gyrus. Significant right precentral and anterior cingulate gyri normalized regional cerebral blood flow increases were observed in the frontal lobe. Both the ATTR and the ATTL conditions, compared to LIS, activated the supplementary motor area, bilateral precentral, and left postcentral cortices without any temporal cortex activation. In addition, the ATTL condition resulted in a right prefrontal cortex activation. Pooling the 14 subjects revealed an asymmetry in the superior temporal gyrus favoring the cortex contralateral to the attended ear. Two major networks seem thus to be involved during selective auditory attention: (1) a local temporal network, on which selective attention produces a modulation of the functional lateralization, and (2) a frontal network that could mediate the temporal cortex modulation by attention.

A Positron Emission Tomography Study of Binaurally and Dichotically Presented Stimuli: Effects of Level of Language and Directed Attention

Regional cerebral blood flow (rCBF) was measured using positron emission tomography with oxygen-15 labeled water as 10 normal subjects listened to three types of auditory stimuli (environmental sounds, meaningless speech, and words) presented binaurally or dichotically. Binaurally presented environmental sounds and words caused similar bilateral rCBF increases in left and right superior temporal gyri. Dichotically presented stimuli (subjects attended to left or right ears) caused asymmetric activation in the temporal lobes, resulting from increased rCBF in temporal lobe regions contralateral to the attended ear and decreased rCBF in the opposite hemisphere. The results indicate that auditorily presented language and non- language stimuli activate similar temporal regions, that dichotic stimulation dramatically changes rCBF in temporal lobes, and that the change is due both to attentional mechanisms and to hemispheric specialization.

Maintien durable de l'orientation de l'attention en écoute dichotique: comparaison entre un avertisseur verbal et un avertisseur sonore latéralisé

Summary: Auditory orienting of attention in dichotic listening. An experiment examined how the orienting of auditory attention is maintained over time (front 1,5 seconds to 3 seconds) as a function of cue type (the words « right » or « left » presented binaurally, or a lateralized tone cue). The hypothesis is that, for the longest delay between cue and target, orienting attention to one ear determined by the cue words «left» and «right» presented binaurally leads to a better detection of verbal targets presented dichotically with distractors as compared to orienting determined by a peripheral sound presented only in the to-be-attended ear. Two rates of presentation of the dichotic stimuli pairs were used, resulting in cue/target delays of 1,5 seconds (fast rate) and 3 seconds (slow rate). Two dummy pairs which never contained any target were also inserted between the cue and the target. The main result is an interaction between cue type and the rate of presentation. The mean latency of a correct verbal response was slowest in the left attended ear at a slow rate and when the cue was a lateralized tone. This result suggests that attentional focusing is more easily dissipated when orientation is provoked by a lateralized tone eue. This interpretation is discussed in the context of Posner's (1980) and Mondor and Bryden's (1992a, b and c) proposed distinction between deliberate endogenous orienting and automatized exogenous orienting. This distinction stresses the fact that deliberate orienting of auditory attention leads to a more robust focusing (longer lasting and more resistant to distraction) than automatic exogenous orienting. Key words : orientation of attention, dichotic listening, auditory perception.

Modulation of early sensory processing in human auditory cortex during auditory selective attention.

Neuromagnetic fields were recorded from human subjects as they listened selectively to sequences of rapidly presented tones in one ear while ignoring tones of a different pitch in the opposite ear. Tones in the attended ear evoked larger magnetic brain responses than did unattended tones in the latency ranges 20-50 msec and 80-130 msec poststimulus. Source localization techniques in conjunction with magnetic resonance imaging placed the neural generators of these early attention-sensitive brain responses in auditory cortex on the supratemporal plane. These data demonstrate that focused auditory attention in humans can selectively modulate sensory processing in auditory cortex beginning as early as 20 msec poststimulus, thereby providing strong evidence for an "early selection" mechanism of auditory attention that can regulate auditory input at or before the initial stages of cortical analysis.

Late components of auditory event-related potentials to eight equiprobable stimuli in a target detection task.

Fourteen normal subjects undertook a target detection task in which eight different but equiprobable stimuli were presented in an unpredictable sequence (four tone frequencies to either the left or the right ear). One tone/ear combination was designated as a target, to be responded to with a rapid button press. Event-related potentials were recorded from an array of six scalp electrodes. In Condition 1 no responses were required; in Condition 2 a response was required to the highest tone in one designated ear; in Condition 3 a response was required to the second highest tone in the ear opposite to the Condition 2 target. Event-related potentials to the no-task condition (1) included a P3-type late positive component. P3 increased in amplitude to target tones in Conditions 2 and 3, but showed equally large amplitude increases and some decrease in latency to nontarget tones in those conditions. However, a frontal Slow Wave component was elicited more specifically by target stimuli. An attended ear effect was evident in a processing negativity that extended for some hundreds of milliseconds prefrontally, but tended to be comprised of two separate negativities over fronto-central locations.