Phenotypes and clinical subgroups in vestibular migraine: a cross-sectional study with cluster analysis

OBJECTIVE

The aim of this multicentric cross-sectional study was to collect phenotypes and clinical variability on a large sample of 244 patients enrolled in different university centers in Italy, trying to differentiate subtypes of VM.

BACKGROUND

VM is one of the most frequent episodic vertigo characterized by a great clinical variability for duration of attacks and accompanying symptoms. Diagnosis is based only on clinical history of episodic vertigo in 50% of cases associated with migrainous headache or photo/phonophobia.

METHODS

We enrolled in different university centers 244 patients affected by definite VM according to the criteria of the Barany Society between January 2022 and December 2022. An audiometric examination and a CNS MRI were performed before inclusion. Patients with low-frequency sensorineural hearing loss were not included, as well as patients with an MRI positive otherwise that for microischemic lesions. Patients were asked to characterize vestibular symptoms choosing among (multiple answers were allowed): internal vertigo, dizziness, visuo-vestibular symptoms/external vertigo; onset of vertigo and duration, neurovegetative, and cochlear accompanying symptoms (hearing loss, tinnitus, and fullness during attacks) were collected as well as migrainous headache and/or photo/phonophobia during vertigo; autoimmune disorders were also analyzed. A bedside examination was performed including study of spontaneous-positional nystagmus with infrared video goggles, post head shaking ny, skull vibration test, and video head impulse test.

RESULTS

We included 244 subjects, 181 were females (74.2%). The age of onset of the first vertigo was 36.6 ± 14.5 while of the first headache was 23.2 ± 10.1. A positive correlation has been found between the first headache and the first vertigo. The mean duration of vertigo attacks was 11 ± 16 h. We carried on a cluster analysis to identify subgroups of patients with common clinical features. Four variables allowed to aggregate clusters: age of onset of vertigo, duration of vertigo attacks, presence of migrainous headache during vertigo, and presence of cochlear symptoms during vertigo. We identified 5 clusters: cluster 1/group 1 (23 subjects, 9.4%) characterized by longer duration of vertigo attacks; cluster 2/group 2 (52 subjects, 21.3%) characterized by absence of migrainous headache and cochlear symptoms during vertigo; cluster 3/group 3 (44 subjects, 18%) characterized by presence of cochlear symptoms during vertigo but not headache; cluster 4/group 4 (57 subjects, 23.4%) by the presence of both cochlear symptoms and migrainous headache during vertigo; cluster 5/group 5 (68 subjects, 27.9%) characterized by migrainous headache but no cochlear symptoms during vertigo.

CONCLUSION

VM is with any evidence a heterogeneous disorder and clinical presentations exhibit a great variability. In VM, both symptoms orienting toward a peripheral mechanism (cochlear symptoms) and central ones (long lasting positional non-paroxysmal vertigo) may coexist. Our study is the first published trying to characterize subgroups of VM subjects, thus orienting toward different pathophysiological mechanisms.

A Systematic Review on the Genetic Contribution to Tinnitus

PURPOSE

To assess the available evidence to support a genetic contribution and define the role of common and rare variants in tinnitus.

METHODS

After a systematic search and quality assessment, 31 records including 383,063 patients were selected (14 epidemiological studies and 17 genetic association studies). General information on the sample size, age, sex, tinnitus prevalence, severe tinnitus distribution, and sensorineural hearing loss was retrieved. Studies that did not include data on hearing assessment were excluded. Relative frequencies were used for qualitative variables to compare different studies and to obtain average values. Genetic variants and genes were listed and clustered according to their potential role in tinnitus development.

RESULTS

The average prevalence of tinnitus estimated from population-based studies was 26.3% for any tinnitus, and 20% of patients with tinnitus reported it as an annoying symptom. One study has reported population-specific differences in the prevalence of tinnitus, the white ancestry being the population with a higher prevalence. Genome-wide association studies have identified and replicated two common variants in the Chinese population (rs2846071; rs4149577) in the intron of TNFRSF1A, associated with noise-induced tinnitus. Moreover, gene burden analyses in sequencing data from Spanish and Swede patients with severe tinnitus have identified and replicated ANK2, AKAP9, and TSC2 genes.

CONCLUSIONS

The genetic contribution to tinnitus is starting to be revealed and it shows population-specific effects in European and Asian populations. The common allelic variants associated with tinnitus that showed replication are associated with noise-induced tinnitus. Although severe tinnitus has been associated with rare variants with large effect, their role on hearing or hyperacusis has not been established.

Review and Perspective on Brain Bases of Tinnitus

In advancing our understanding of tinnitus, some of the more impactful contributions in the past two decades have come from human brain imaging studies, specifically the idea of both auditory and extra-auditory neural networks that mediate tinnitus. These networks subserve both the perception of tinnitus and the psychological reaction to chronic, continuous tinnitus. In this article, we review particular studies that report on the nodes and links of such neural networks and their inter-network connections. Innovative neuroimaging tools have contributed significantly to the increased understanding of anatomical and functional connections of attention, emotion-processing, and default mode networks in adults with tinnitus. We differentiate between the neural correlates of tinnitus and those of comorbid hearing loss; surprisingly, tinnitus and hearing loss when they co-occur are not necessarily additive in their impact and, in rare cases, additional tinnitus may act to mitigate the consequences of hearing loss alone on the brain. The scale of tinnitus severity also appears to have an impact on brain networks, with some of the alterations typically attributed to tinnitus reaching significance only in the case of bothersome tinnitus. As we learn more about comorbid conditions of tinnitus, such as depression, anxiety, hyperacusis, or even aging, their contributions to the network-level changes observed in tinnitus will need to be parsed out in a manner similar to what is currently being done for hearing loss or severity. Together, such studies advance our understanding of the heterogeneity of tinnitus and will lead to individualized treatment plans.

Functional Brain Regions Linked to Tinnitus Pathology and Compensation During Task Performance: A Systematic Review

OBJECTIVE

To systematically search the literature and organize relevant advancements in the connection between tinnitus and the activity of different functional brain regions using functional magnetic resonance imaging (fMRI).

DATA SOURCES

MEDLINE (OVID), EMBASE (OVID), CINAHL (EBSCO), Web of Science, ProQuest Dissertations & Theses Global, Cochrane Database of Systematic Reviews, and PROSPERO from inception to April 2022.

REVIEW METHODS

Studies with adult human subjects who suffer from tinnitus and underwent fMRI to relate specific regions of interest to tinnitus pathology or compensation were included. In addition, fMRI had to be performed with a paradigm of stimuli that would stimulate auditory brain activity. Exclusion criteria included non-English studies, animal studies, and studies that utilized a resting state magnetic resonance imaging or other imaging modalities.

RESULTS

The auditory cortex may work to dampen the effects of central gain. Results from different studies show variable changes in the Heschl's gyrus (HG), with some showing increased activity and others showing inhibition and volume loss. After controlling for hyperacusis and other confounders, tinnitus does not seem to influence the inferior colliculus (IC) activation. However, there is decreased connectivity between the auditory cortex and IC. The cochlear nucleus (CN) generally shows increased activation in tinnitus patients. fMRI evidence indicates significant inhibition of thalamic gating. Activating the thalamus may be of important therapeutic potential.

CONCLUSION

Patients with tinnitus have significantly altered neuronal firing patterns, especially within the auditory network, when compared to individuals without tinnitus. Tinnitus and hyperacusis commonly coexist, making differentiation of the effects of these 2 phenomena frequently difficult.

Persian Version of the Hyperacusis Questionnaire: Psychometric Evaluation and Prevalence Determination

PURPOSE

Hyperacusis is an uncommon hearing disorder, known as increased sensitivity to daily surrounding sounds. This disorder can profoundly affect people's daily activities. The studies conducted about hyperacusis are very limited in Iran. The purposes of this study are the psychometric evaluation of the Persian version of the Hyperacusis Questionnaire (PHQ) and the investigation of its prevalence.

METHOD

This cross-sectional study was accomplished on 203 young university students with normal hearing sensitivity. After translating the questionnaire, the psychometric properties of the PHQ were evaluated by content validity ratio (CVR) and index (CVI) and exploratory factor analysis (EFA). Students were evaluated by clinical audiology tests, the loudness discomfort level (LDL) measurement, and answering the PHQ. The research data collection was done from April to November 2022. Otoscopy, clinical and speech audiometry, and LDL were all executed, respectively. The participants directly answered the PHQ. All statistical analyses were performed using SPSS software Version 26.

RESULTS

The PHQ demonstrated acceptable validity and reliability, Cronbach's alpha (.81), CVI (> 0.88), and CVR (> 0.98). EFA revealed four dimensions of the questionnaire. Of the participants, four (2%) were identified as suffering from hyperacusis. The PHQ showed the possibility of differences between genders.

CONCLUSIONS

The psychometric evaluations of the PHQ were found to be acceptable and can be used in future studies. The prevalence of hyperacusis in our sample was 2%, and estimated to be higher in females. These findings suggest the need for further research on hyperacusis in Iranian population and specified studies to compare the two genders.

Changes of migraine aura with advancing age of patients

AIM

Given the similar presentation of migraine aura and acute ischemic stroke, advancing patient age might change the characteristics of migraine with aura (MA) and be clinically important. Clinical data, however, are limited. Experimental studies indicate a decrease in the magnitude of cortical spreading depression (CSD), the pathophysiological correlate of migraine aura, with advancing age. Our study aimed to assess the influence of age on the clinical features of MA.

METHODS

Three hundred and forty-three patients were interviewed using a structured questionnaire. The questions covered the headache characteristics and symptom types including the characteristics of the C-criterion, as defined by the International Classification of Headache Disorders 3rd Edition. The association of age with MA characteristics was assessed.

RESULTS

The median age was 29 (IQR 28-52) and 235 of the 343 patients were women (69%). Individual symptoms of the C-criterion such as gradual aura spreading over longer than 5 min (P < 0.001), two or more aura symptoms occurring in succession (P = 0.005), duration of at least one MA symptom for longer than 60 min (P = 0.004), and associated headache (P = 0.01) were more frequent in younger patients. The number of symptoms including the C-characteristics decreased with increasing age (P < 0.001). Patients with sensory (P < 0.001), motor (P = 0.004) and speech disturbance (P = 0.02) were younger, and older patients with headache had less photophobia (P = 0.04) and phonophobia (P = 0.03). Sensitivity analyses yielded similar results.

CONCLUSION

The frequency of typical characteristics of migraine aura and migraine headache including photophobia and phonophobia decreases with advancing patient age. This might have potentially difficult implications for the diagnosis of MA in the elderly.

Impact of anti-CGRP monoclonal antibodies on migraine attack accompanying symptoms: A real-world evidence study

BACKGROUND

Clinical trials on anti-calcitonin gene-related peptide monoclonal antibodies poorly investigated their impact on migraine accompanying symptoms.

OBJECTIVE

To evaluate the impact of basal accompanying symptoms on anti-CGRP monoclonal antibodies treatment response and their evolution after six months of treatment in migraine patients.

METHODS

Patients with migraine diagnosis seen in the Headache Clinic and treated with erenumab, galcanezumab or fremanezumab were prospectively recruited. They completed a daily eDiary which provided data on headache frequency and the following accompanying symptoms of each day: photophobia, phonophobia, nausea, dizziness, and aura. Patients were classified as responders or non-responders based on 50% or greater reduction in headache days per month at month 6 (≥50% response rate). Accompanying symptoms ratios based on headache days per month were assessed per patient at baseline and after three and six months. Comparisons for basal characteristics, basal accompanying symptoms ratios and their evolution after six months between responders and non-responders were performed.

RESULTS

One hundred and fifty-eight patients were included, 44% (69/158) showed ≥50% response rate after six months. A significant reduction in headache days per month in both groups was found at month 6 (-9.4 days/month in ≥50% response rate group; p < 0.001, -2.2 days/month in <50% response rate group; p = 0.004). Additionally, significant decreases in photophobia (-19.5%, p < 0.001), phonophobia (-12.1%, p = 0.010) and aura ratios (-25.1%, p = 0.008) were found in ≥50% response rate group. No statistically significant reductions were found in nausea and dizziness in any group since their reduction was correlated with the decrease in headache days per month. Higher photophobia ratios at baseline were predictive of an increased response between months 3 and 6 (Incidence Risk Ratio = 0.928, p = 0.040).

CONCLUSIONS

The days per month with photophobia, phonophobia and aura decreased at a higher rate than headache days per month after six months in the ≥50% response group. Higher photophobia ratios were associated with higher response rates between three and six months. It could indicate an involvement of peripheral CGRP in photophobia as well as a central modulation of migraine through these treatments which mainly act on the periphery.

New horizons in hearing conditions

Hearing conditions such as hearing loss, tinnitus and hyperacusis are highly prevalent in the population and can severely impact communication and quality of life. Hearing is affected by multiple factors, including heredity, noise exposure, age, sex, ear disorders and lifestyle factors. Globally, hearing loss affects over 80% of adults aged 80 years and older, is often experienced in combination with other long-term health conditions and is a mid-life risk factor for dementia. To form a themed collection, we searched Age and Ageing for articles on hearing conditions published from 2000 onwards. This resulted in 22 articles included within the collection. They examined a range of important topics related to hearing healthcare and research, including noise-induced hearing loss, health service quality and safety, psychological and psychosocial consequences of hearing loss and co-morbidities of hearing loss. All articles reported on hearing loss; there were no published articles with a primary focus on other hearing conditions such as tinnitus or hyperacusis, on the health of older people from the Deaf community or on users of Cochlear implants, suggesting key gaps in knowledge and targets for future research. This New Horizons article highlights novel directions in research and practice and takes a forward look at how research into hearing conditions may develop in years to come. It highlights opportunities for the growth of patient-centred research and hearing healthcare supported by the better integration of health and care services as well as cross-speciality working to include common co-morbid health conditions.

Audiological and vestibular symptoms following SARS-CoV-2 infection and COVID-19 vaccination in children aged 5-11 years

PURPOSE

The present study assessed the prevalence of audio-vestibular symptoms following SARS-COV-2 infection or COVID-19 vaccination among children, comparing the two groups. A further aim was to evaluate whether children with pre-existing unilateral hearing loss were more prone to adverse events.

MATERIALS AND METHODS

This retrospective study included children aged 5-11 years with normal hearing or a proven history of unilateral hearing loss who contracted SARS-CoV-2 or received two doses of COVID-19 vaccine. Tinnitus, hyperacusis, aural fullness, otalgia, otorrhea, new-onset hearing loss, vertigo and dizziness were investigated as possible complications of SARS-CoV-2 infection or the COVID-19 vaccine.

RESULTS

This study included 272 children (143 boys, 129 girls), with a mean age of 7.8 ± 2.3 years. Among these, 120 were affected by pre-existing unilateral hearing loss. The most common audio-vestibular symptoms reported by children following SARS-CoV-2 infection and COVID-19 vaccination were aural fullness (33/132, 25 %) and dizziness (5/140, 3.6 %), respectively. All symptoms following COVID-19 vaccination resolved within 24 h. Compared to children who received the COVID-19 vaccine, those infected with SARS-CoV-2 had a higher prevalence of tinnitus (p = 0.009), hyperacusis (p = 0.003), aural fullness (p < 0.001), otalgia (p < 0.001), otorrhea (p < 0.001), and vertigo (p = 0.006). Two girls also experienced new-onset unilateral sensorineural hearing loss following SARS-CoV-2 infection. Children with a known history of unilateral hearing loss did not have a higher prevalence of audio-vestibular symptoms than children with normal hearing.

CONCLUSIONS

Our results suggest that the COVID-19 vaccine is safe and can be recommended for children with unilateral hearing loss without fear of possible audio-vestibular sequelae.

Perceptions of various treatment approaches for adults and children with misophonia

OBJECTIVE

Misophonia is a complex disorder characterized by a heightened reaction to certain sounds and associated stimuli. While there is no uniformly accepted treatment to date, different intervention approaches are being investigated. Individual's perceptions of different misophonia treatment methods may affect compliance and satisfaction with treatment options. We sought to gather data on patient perceptions of currently available misophonia treatments.

METHODS

Using an online survey, we collected data about treatment preferences, treatment usage, and diagnosis history from parents of children with misophonia (N = 141) and adults with misophonia (N = 252).

RESULTS

Most respondents were not satisfied with misophonia treatments that they or their children had previously received. Audiologic interventions including active and passive noise cancelling and lifestyle modifications were rated as most appropriate for treatment of misophonia by both parent and adult respondents.

LIMITATIONS

Because of the descriptive nature of this study, we chose to use a completer-only approach to ensure the data reflect the true responses of participants, though this did result in a meaningful proportion of missing data. Participants were selected through convenience sampling and responses were self-reported. Individuals with more severe misophonia symptoms may be more likely to participate and complete a research survey.

CONCLUSIONS

Most interventions are considered inappropriate by parents of youth with misophonia and by adults with misophonia. This should be interpreted in the light of a general lack of misophonia-specific interventions. Findings suggest dissatisfaction with currently available treatments and an opportunity for development of effective treatment strategies corresponding to participants' preferences. Deeper understanding of treatment preferences has the potential to guide future treatment development.

The Berlin Misophonia Questionnaire Revised (BMQ-R): Development and validation of a symptom-oriented diagnostical instrument for the measurement of misophonia

Misophonia is a clinical syndrome which is characterized by intense emotional and physical reactions to idiosyncratic sounds. However, its psychometric measurement is still in the early stages. This study describes the optimization of a self-report instrument, the Berlin Misophonia Questionnaire (BMQ), and addresses its strengths in comparison to existing psychometric measures. This new measure integrates contemporary empirical findings and is based on the latest criteria of misophonia. A cross-sectional online study was conducted using data of 952 affected as well as non-affected individuals. The final BMQ-R consists of 77 items in 21 scales, which were selected using a probabilistic item selection algorithm (Ant Colony Optimization). The results of confirmatory factor analyses, the assessment of reliability, and an extensive construct validation procedure supported the reliability and validity of the developed scales. One outstanding strength of the BMQ-R is its comprehensive measurement of misophonic emotional and physical responses. The instrument further allows for distinguishing between behavioral, cognitive, and emotional dysregulation; the measurement of clinical insight and significance; as well as discerning reactive and anticipating avoidance strategies. Our work offers several improvements to the measurement of misophonia by providing a reliable and valid multidimensional diagnostical instrument. In line with the scientific consensus on defining misophonia, the BMQ-R allows to formally recognize individuals with misophonia and so to compare findings of future studies. Undoubtedly, this measure fills a research gap, which we hope will facilitate the investigation of causes and treatment of misophonia.

Misophonia: A Systematic Review of Current and Future Trends in This Emerging Clinical Field

Misophonia is a scarcely known disorder. This systematic review (1) offers a quantitative and qualitative analysis of the literature since 2001, (2) identifies the most relevant aspects but also controversies, (3) identifies the theoretical and methodological approaches, and (4) highlights the outstanding advances until May 2022 as well as aspects that remain unknown and deserve future research efforts. Misophonia is characterized by strong physiological, emotional, and behavioral reactions to auditory, visual, and/or kinesthetic stimuli of different nature regardless of their physical characteristics. These misophonic responses include anger, general discomfort, disgust, anxiety, and avoidance and escape behaviors, and decrease the quality of life of the people with the disorder and their relatives. There is no consensus on the diagnostic criteria yet. High comorbidity between misophonia and other psychiatric and auditory disorders is reported. Importantly, the confusion with other disorders contributes to its underdiagnosis. In recent years, assessment systems with good psychometric properties have increased considerably, as have treatment proposals. Although misophonia is not yet included in international classification systems, it is an emerging field of growing scientific and clinical interest.

The proposed criteria for high perceived misophonia in young healthy adults and the association between Misophonia symptoms and noise sensitivity

CONTEXT

The association between noise sensitivity and misophonia has not been explored in any population, according to the available literature.

AIMS

To assess the proportion of misophonia symptoms among young healthy adults, to propose the criteria for high perceived misophonia, and to explore the association between misophonia with noise sensitivity with adjustment for sex, age, perceived anxiety, and depression.

SETTINGS AND DESIGN

A cross-sectional study on 1132 medical students, aged 21.4 ± 2.1 years.

METHODS AND MATERIAL

Misophonia symptoms were self-reported using the Amsterdam Misophonia Scale. Nine criteria for high perceived misophonia are proposed. Noise sensitivity was measured with Weinstein scale. Perceived anxiety and depression were measured using the Hamilton Anxiety Rating Scale and the Hamilton Depression Rating Scale, respectively.

STATISTICAL ANALYSIS USED

Multiple logistic regression.

RESULTS

Almost half of the students reported the feeling of irritation against people making provoking sounds. Only one in 10 claimed the feeling of loss of self-control when exposed to provoking sounds. High noise sensitivity and high depression were associated with higher odds of meeting the criteria for high perceived misophonia.

CONCLUSION

Noise-sensitive students are at higher risk of reporting misophonia symptoms and of being classified with high perceived misophonia. The combination of at least four or more symptoms, which classifies every 10th student with high perceived misophonia, is proposed as a self-assessment tool for epidemiological studies among young healthy adults.

Auditory hypersensitivity and processing deficits in a rat model of fragile X syndrome

Fragile X (FX) syndrome is one of the leading inherited causes of autism spectrum disorder (ASD). A majority of FX and ASD patients exhibit sensory hypersensitivity, including auditory hypersensitivity or hyperacusis, a condition in which everyday sounds are perceived as much louder than normal. Auditory processing deficits in FX and ASD also afford the opportunity to develop objective and quantifiable outcome measures that are likely to translate between humans and animal models due to the well-conserved nature of the auditory system and well-developed behavioral read-outs of sound perception. Therefore, in this study we characterized auditory hypersensitivity in a Fmr1 knockout (KO) transgenic rat model of FX using an operant conditioning task to assess sound detection thresholds and suprathreshold auditory reaction time-intensity (RT-I) functions, a reliable psychoacoustic measure of loudness growth, at a variety of stimulus frequencies, bandwidths, and durations. Male Fmr1 KO and littermate WT rats both learned the task at the same rate and exhibited normal hearing thresholds. However, Fmr1 KO rats had faster auditory RTs over a broad range of intensities and steeper RT-I slopes than WT controls, perceptual evidence of excessive loudness growth in Fmr1 KO rats. Furthermore, we found that Fmr1 KO animals exhibited abnormal perceptual integration of sound duration and bandwidth, with diminished temporal but enhanced spectral integration of sound intensity. Because temporal and spectral integration of sound stimuli were altered in opposite directions in Fmr1 KO rats, this suggests that abnormal RTs in these animals are evidence of aberrant auditory processing rather than generalized hyperactivity or altered motor responses. Together, these results are indicative of fundamental changes to low-level auditory processing in Fmr1 KO animals. Finally, we demonstrated that antagonism of metabotropic glutamate receptor 5 (mGlu5) selectively and dose-dependently restored normal loudness growth in Fmr1 KO rats, suggesting a pharmacologic approach for alleviating sensory hypersensitivity associated with FX. This study leverages the tractable nature of the auditory system and the unique behavioral advantages of rats to provide important insights into the nature of a centrally important yet understudied aspect of FX and ASD.

Too Blind to See the Elephant? Why Neuroscientists Ought to Be Interested in Tinnitus

A curative therapy for tinnitus currently does not exist. One may actually exist but cannot currently be causally linked to tinnitus due to the lack of consistency of concepts about the neural correlate of tinnitus. Depending on predictions, these concepts would require either a suppression or enhancement of brain activity or an increase in inhibition or disinhibition. Although procedures with a potential to silence tinnitus may exist, the lack of rationale for their curative success hampers an optimization of therapeutic protocols. We discuss here six candidate contributors to tinnitus that have been suggested by a variety of scientific experts in the field and that were addressed in a virtual panel discussion at the ARO round table in February 2021. In this discussion, several potential tinnitus contributors were considered: (i) inhibitory circuits, (ii) attention, (iii) stress, (iv) unidentified sub-entities, (v) maladaptive information transmission, and (vi) minor cochlear deafferentation. Finally, (vii) some potential therapeutic approaches were discussed. The results of this discussion is reflected here in view of potential blind spots that may still remain and that have been ignored in most tinnitus literature. We strongly suggest to consider the high impact of connecting the controversial findings to unravel the whole complexity of the tinnitus phenomenon; an essential prerequisite for establishing suitable therapeutic approaches.

Family Experiences of Decreased Sound Tolerance in ASD

Decreased sound tolerance (DST) is the most common sensory difficulty experienced by autistic individuals. Parents of 88 autistic children and young adults between the ages of 3 and 30 described coping strategies and physical and emotional responses used to deal with distressing sounds, and their impact on daily activities. Loud, sudden, and high-pitched sounds were most commonly endorsed as distressing, most often causing autistic children and young adults to cover their ears or yell, while producing stress, irritation, fear, and anxiety. Parents reported warning their child, providing breaks, or avoiding noisy settings as the most used coping strategies. Overall, findings indicate that DST leads to fewer opportunities for autistic children and young adults to participate at home, at school, and in the community. Further, results suggest hyperacusis, misophonia, and phonophobia, subtypes of DST, are present in autistic children and young adults.

Olivocochlear efferent effects on perception and behavior

The role of the mammalian auditory olivocochlear efferent system in hearing has long been the subject of debate. Its ability to protect against damaging noise exposure is clear, but whether or not this is the primary function of a system that evolved in the absence of industrial noise remains controversial. Here we review the behavioral consequences of olivocochlear activation and diminished olivocochlear function. Attempts to demonstrate a role for hearing in noise have yielded conflicting results in both animal and human studies. A role in selective attention to sounds in the presence of distractors, or attention to visual stimuli in the presence of competing auditory stimuli, has been established in animal models, but again behavioral studies in humans remain equivocal. Auditory processing deficits occur in models of congenital olivocochlear dysfunction, but these deficits likely reflect abnormal central auditory development rather than direct effects of olivocochlear feedback. Additional proposed roles in age-related hearing loss, tinnitus, hyperacusis, and binaural or spatial hearing, are intriguing, but require additional study. These behavioral studies almost exclusively focus on medial olivocochlear effects, and many relied on lesioning techniques that can have unspecific effects. The consequences of lateral olivocochlear and of corticofugal pathway activation for perception remain unknown. As new tools for targeted manipulation of olivocochlear neurons emerge, there is potential for a transformation of our understanding of the role of the olivocochlear system in behavior across species.

A review of decreased sound tolerance in autism: Definitions, phenomenology, and potential mechanisms

Atypical behavioral responses to environmental sounds are common in autistic children and adults, with 50-70 % of this population exhibiting decreased sound tolerance (DST) at some point in their lives. This symptom is a source of significant distress and impairment across the lifespan, contributing to anxiety, challenging behaviors, reduced community participation, and school/workplace difficulties. However, relatively little is known about its phenomenology or neurocognitive underpinnings. The present article synthesizes a large body of literature on the phenomenology and pathophysiology of DST-related conditions to generate a comprehensive theoretical account of DST in autism. Notably, we argue against conceptualizing DST as a unified construct, suggesting that it be separated into three phenomenologically distinct conditions: hyperacusis (the perception of everyday sounds as excessively loud or painful), misophonia (an acquired aversive reaction to specific sounds), and phonophobia (a specific phobia of sound), each responsible for a portion of observed DST behaviors. We further elaborate our framework by proposing preliminary neurocognitive models of hyperacusis, misophonia, and phonophobia that incorporate neurophysiologic findings from studies of autism.

Development and Psychometric Properties of MisoQuest-A New Self-Report Questionnaire for Misophonia

Background: Misophonia is a condition related to experiencing psychophysiological sensations when exposed to specific sound triggers. In spite of progress in research on the subject, a fully validated questionnaire assessing misophonia has not been published yet. The goal of this study was to create and validate a new questionnaire to measure misophonia. Methods: MisoQuest is based on the diagnostic criteria proposed by Schröder et al. in 2013, with minor changes implemented by the authors of MisoQuest. A total of 705 participants took part in the study, completing the online questionnaires. Exploratory Factor Analysis (EFA) and analyses using the Item Response Theory (IRT) were performed. Internal consistency was evaluated with Cronbach's alpha. Results: The reliability of the MisoQuest was excellent (α = 0.955). The stability at five weeks was strong. There was a significant difference in results between people classified as those with misophonia and those without misophonia. Conclusions: MisoQuest has good psychometric values and can be helpful in the identification of misophonia. A deeper analysis showed that certain triggers might be more specific for people with misophonia. Consideration of violent behavior in response to misophonic triggers as a symptom of misophonia was undermined.

Identifying and prioritising unanswered research questions for people with hyperacusis: James Lind Alliance Hyperacusis Priority Setting Partnership

OBJECTIVE

To determine research priorities in hyperacusis that key stakeholders agree are the most important.

DESIGN/SETTING

A priority setting partnership using two international surveys, and a UK prioritisation workshop, adhering to the six-staged methodology outlined by the James Lind Alliance.

PARTICIPANTS

People with lived experience of hyperacusis, parents/carers, family and friends, educational professionals and healthcare professionals who support and/or treat adults and children who experience hyperacusis, including but not limited to surgeons, audiologists, psychologists and hearing therapists.

METHODS

The priority setting partnership was conducted from August 2017 to July 2018. An international identification survey asked respondents to submit any questions/uncertainties about hyperacusis. Uncertainties were categorised, refined and rephrased into representative indicative questions using thematic analysis techniques. These questions were verified as 'unanswered' through searches of current evidence. A second international survey asked respondents to vote for their top 10 priority questions. A shortlist of questions that represented votes from all stakeholder groups was prioritised into a top 10 at the final prioritisation workshop (UK).

RESULTS

In the identification survey, 312 respondents submitted 2730 uncertainties. Of those uncertainties, 593 were removed as out of scope, and the remaining were refined into 85 indicative questions. None of the indicative questions had already been answered in research. The second survey collected votes from 327 respondents, which resulted in a shortlist of 28 representative questions for the final workshop. Consensus was reached on the top 10 priorities for future research, including identifying causes and underlying mechanisms, effective management and training for healthcare professionals.

CONCLUSIONS

These priorities were identified and shaped by people with lived experience, parents/carers and healthcare professionals, and as such are an essential resource for directing future research in hyperacusis. Researchers and funders should focus on addressing these priorities.

Clinical manifestations of hydropic ear disease (Menière's)

INTRODUCTION

Hydropic ear disease, initially described by and named after Prosper Menière, is one of the most frequent vertigo disorders and one of the most frequent inner ear disorders. It is the syndrome of endolymphatic hydrops which until 2007 could be diagnostically confirmed only by post-mortem histology. In the past, various attempts to formulate clinical diagnostic criteria have been undertaken but were hampered by the inability to ascertain the diagnosis in living patients. With the milestone achievement of endolymphatic hydrops imaging, today the pathology can be ascertained. In this study, we have performed a detailed analysis of the clinical features of hydropic ear disease for the first time by examining a large cohort of patients with morphologically confirmed endolymphatic hydrops using a detailed physician-administered neurotologic face-to-face interview.

RESULTS

During a hydropic vertigo attack, the patients report nausea, vomiting, sweating, urge to defecate, urge to urinate, phosphenes, headache, photophobia, phonophobia and even transient loss of consciousness. A third of the patients does not experience auditory symptoms during the vertigo attacks. Vertigo attacks last less than 20 min in more than one-fourth of the patients. Audiometric hearing loss has its greatest diagnostic value at the frequencies of 1 kHz and below. Cochleovestibular symptom onset simultaneity is associated with a high frequency of drop-attacks. Migraine and autoimmune disorders are not associated with hydropic ear disease.

CONCLUSION

This study marks the beginning of the clinical characterization of hydropic ear disease. The findings have important implications for the future formulation of clinical diagnostic criteria.

Hearing Loss, Tinnitus, Hyperacusis, and Diplacusis in Professional Musicians: A Systematic Review

Professional musicians (PMs) are at high risk of developing hearing loss (HL) and other audiological symptoms such as tinnitus, hyperacusis, and diplacusis. The aim of this systematic review is to (A) assess the risk of developing HL and audiological symptoms in PMs and (B) evaluate if different music genres (Pop/Rock Music—PR; Classical Music—CL) expose PMs to different levels of risk of developing such conditions. Forty-one articles including 4618 PMs were included in the study. HL was found in 38.6% PMs; prevalence was significantly higher among PR (63.5%) than CL (32.8%) PMs; HL mainly affected the high frequencies in the 3000-6000 Hz range and was symmetric in 68% PR PMs and in 44.5% CL PMs. Tinnitus was the most common audiological symptom, followed by hyperacusis and diplacusis. Tinnitus was almost equally distributed between PR and CL PMs; diplacusis was more common in CL than in PR PMs, while prevalence of hyperacusis was higher among PR PMs. Our review showed that PR musicians have a higher risk of developing HL compared to CL PMs; exposure to sounds of high frequency and intensity and absence of ear protection may justify these results. Difference in HL symmetry could be explained by the type of instruments used and consequent single-sided exposure.

Discrimination of amplitude-modulation depth by subjects with normal and impaired hearing

The loudness recruitment associated with cochlear hearing loss increases the perceived amount of amplitude modulation (AM), called "fluctuation strength." For normal-hearing (NH) subjects, fluctuation strength "saturates" when the AM depth is high. If such saturation occurs for hearing-impaired (HI) subjects, they may show poorer AM depth discrimination than NH subjects when the reference AM depth is high. To test this hypothesis, AM depth discrimination of a 4-kHz sinusoidal carrier, modulated at a rate of 4 or 16 Hz, was measured in a two-alternative forced-choice task for reference modulation depths, m_ref, of 0.5, 0.6, and 0.7. AM detection was assessed using m_ref = 0. Ten older HI subjects, and five young and five older NH subjects were tested. Psychometric functions were measured using five target modulation depths for each m_ref. For AM depth discrimination, the HI subjects performed more poorly than the NH subjects, both at 30 dB sensation level (SL) and 75 dB sound pressure level (SPL). However, for AM detection, the HI subjects performed better than the NH subjects at 30 dB SL; there was no significant difference between the HI and NH groups at 75 dB SPL. The results for the NH subjects were not affected by age.

Modulation masking within and across carriers for subjects with normal and impaired hearing

The detection of amplitude modulation (AM) of a carrier can be impaired by additional (masker) AM applied to the same carrier (within-carrier modulation masking, MM) or to a different carrier (across-carrier MM). These two types of MM were compared for young normal-hearing and older hearing-impaired subjects. The signal was 4- or 16-Hz sinusoidal AM of a 4000-Hz carrier. Masker AM with depth 0.4 was applied either to the same carrier or to a carrier at 3179 or 2518 Hz. The masker AM rate was 0.25, 0.5, 1, 2, or 4 times the signal rate. The signal AM depth was varied adaptively to determine the threshold. Both within-carrier and across-carrier MM patterns were similar for the two groups, suggesting that the hypothetical modulation filters are not affected by hearing loss or age. The signal AM detection thresholds were also similar for the two groups. Thresholds in the absence of masker AM were lower (better) for the older hearing-impaired than for the young normal-hearing subjects. Since the masked modulation thresholds were similar for the two groups, it seems unlikely that abnormal MM contributes to the difficulties experienced by older hearing-impaired people in understanding speech in background sounds.

[Decreased sound tolerance and tinnitus]

Decreased sound tolerance includes hyperacusis and/or misphobia (phonophobia). As a commonly subjective symptom, tinnitus is defined to be a sound perceived in the ear or head without corresponding sound or electrical stimulus in the surrounding environment. It is usually occurred with or without hearing loss or harmful psychic reaction, which includes dyssomnia, annoy, rage, anxiety, depress, hard to concentrate, etc. Frequently, tinnitus is accompanied by decreased sound tolerance, while this text is aimed to review the correlated concepts of decreased sound tolerance,and focus on the hyperacusis which is a more common symptom.

Long-term assessment of auditory changes resulting from a single noise exposure associated with non-occupational activities

We examined the long-term sequelae in both ears of 42 patients who reported the occurrence of auditory changes resulting from a single exposure to intense sound levels during non-occupational activities. We divided these patients into two groups, based upon noise exposures of either continuous duration or single high-energy impulse. Audiometric data were available for each of these subjects shortly after their noise-exposure events and follow-up examinations took place more than one year after the noise occurrence (range: 1-16 years). The initial median hearing loss for the continuous-type noise exposure group at 3-8 kHz was found to be 9 dB, relative to the age-appropriate norms, in the more affected ears, and hearing function was found to have returned to normal levels at follow-up. The same initial hearing loss was measured for the impulse-type noise group, but a residual hearing loss of 4 dB was measured at follow-up. Furthermore, the majority of the subjects from both groups reported tinnitus and hypersensitivity to sound at follow-up, but with minimal impact on their lives.

Perception of clear fricatives by normal-hearing and simulated hearing-impaired listeners

Speakers may adapt the phonetic details of their productions when they anticipate perceptual difficulty or comprehension failure on the part of a listener. Previous research suggests that a speaking style known as clear speech is more intelligible overall than casual, conversational speech for a variety of listener populations. However, it is unknown whether clear speech improves the intelligibility of fricative consonants specifically, or how its effects on fricative perception might differ depending on listener population. The primary goal of this study was to determine whether clear speech enhances fricative intelligibility for normal-hearing listeners and listeners with simulated impairment. Two experiments measured babble signal-to-noise ratio thresholds for fricative minimal pair distinctions for 14 normal-hearing listeners and 14 listeners with simulated sloping, recruiting impairment. Results indicated that clear speech helped both groups overall. However, for impaired listeners, reliable clear speech intelligibility advantages were not found for non-sibilant pairs. Correlation analyses comparing acoustic and perceptual data indicated that a shift of energy concentration toward higher frequency regions and greater source strength contributed to the clear speech effect for normal-hearing listeners. Correlations between acoustic and perceptual data were less consistent for listeners with simulated impairment, and suggested that lower-frequency information may play a role.

[Recruitment in presbycusis]

Presbycusis is characterised by a sensorineural hearing loss, mainly in high frequencies, symmetrical and progressive and poor understanding. Recuritment, typical in cochlear hearing loss, would be present in cases of sensorial presbycusis which runs mainly in cochlear pathologies. We analyse variables and their possible interrelations with recruitment in 241 presbycusic patients.

Auditory-nerve rate responses are inconsistent with common hypotheses for the neural correlates of loudness recruitment

A number of perceptual phenomena related to normal and impaired level coding can be accounted for by the degree of compression in the basilar-membrane (BM) magnitude response. However, the narrow dynamic ranges of auditory-nerve (AN) fibers complicate these arguments. Because the AN serves as an information bottleneck, an improved understanding of the neural coding of level may clarify some of the limitations of current hearing aids. Here three hypotheses for the neural correlate of loudness recruitment were evaluated based on AN responses from normal-hearing cats and from cats with a noise-induced hearing loss (NIHL). Auditory-nerve fiber rate-level functions for tones were analyzed to test the following hypotheses: Loudness recruitment results from steeper AN rate functions after impairment. This hypothesis was not supported; AN rate functions were not steeper than normal following NIHL, despite steeper estimated BM responses based on the AN data. Loudness is based on the total AN discharge count, and recruitment results from an abnormally rapid spread of excitation after impairment. Whereas abnormal spread of excitation can be observed, steeper growth of total AN rate is not seen over the range of sound levels where recruitment is observed in human listeners. Loudness of a narrowband stimulus is based on AN responses in a narrow BF region, and recruitment results from compression of the AN-fiber threshold distribution after impairment. This hypothesis was not supported because there was no evidence that impaired AN threshold distributions were compressed and the growth of AN activity summed across BFs near the stimulus frequency was shallower than normal.Overall, these results suggest that loudness recruitment cannot be accounted for based on summed AN rate responses and may depend on neural mechanisms involved in the central representation of intensity.

The effects of neural synchronization and peripheral compression on the acoustic-reflex threshold

This study investigates the acoustic reflex threshold (ART) dependency on stimulus phase utilizing low-level reflex audiometry [Neumann et al., Audiol. Neuro-Otol. 1, 359-369 (1996)]. The goal is to obtain optimal broadband stimuli for elicitation of the acoustic reflex and to obtain objective determinations of cochlear hearing loss. Three types of tone complexes with different phase characteristics were investigated: A stimulus that compensates for basilar-membrane dispersion, thus causing a large overall neural synchrony (basilar-membrane tone complex-BMTC), the temporally inversed stimulus (iBMTC), and random-phase tone complexes (rTC). The ARTs were measured in eight normal-hearing and six hearing-impaired subjects. Five different conditions of peak amplitude and stimulus repetition rate were used for each stimulus type. The results of the present study suggest that the ART is influenced by at least two different factors: (a) the degree of synchrony of neural activity across frequency, and (b) the fast-acting compression mechanism in the cochlea that is reduced in the case of a sensorineural hearing loss. The results allow a clear distinction of the two subjects groups based on the different ART for the utilized types and conditions of the stimuli. These differences might be useful for objective recruitment detection in clinical diagnostics.

A revised model of loudness perception applied to cochlear hearing loss

We previously described a model for loudness perception for people with cochlear hearing loss. However, that model is incompatible with our most recent and most satisfactory model of loudness for normal hearing. Here, we describe a loudness model that is applicable to both normal and impaired hearing. In contrast to our earlier model for impaired hearing, the new model correctly predicts: (1) that a sound at absolute threshold has a small but finite loudness; (2) that, for levels very close to the absolute threshold, the rate of growth of loudness is similar for normal ears and ears with cochlear hearing loss; (3) the relation between monaural and binaural threshold and loudness; (4) recent measures of equal-loudness contours. Like the earlier model, the new model can account for the loudness recruitment and reduced loudness summation that are typically associated with cochlear hearing loss.

Speech perception, localization, and lateralization with bilateral cochlear implants

Five bilateral cochlear implant users were tested for their localization abilities and speech understanding in noise, for both monaural and binaural listening conditions. They also participated in lateralization tasks to assess the impact of variations in interaural time delays (ITDs) and interaural level differences (ILDs) for electrical pulse trains under direct computer control. The localization task used pink noise bursts presented from an eight-loudspeaker array spanning an arc of approximately 108 degrees in front of the listeners at ear level (0-degree elevation). Subjects showed large benefits from bilateral device use compared to either side alone. Typical root-mean-square (rms) averaged errors across all eight loudspeakers in the array were about 10 degrees for bilateral device use and ranged from 20 degrees to 60 degrees using either ear alone. Speech reception thresholds (SRTs) were measured for sentences presented from directly in front of the listeners (0 degrees) in spectrally matching speech-weighted noise at either 0 degrees, +90 degrees or -90 degrees for four subjects out of five tested who could perform the task. For noise to either side, bilateral device use showed a substantial benefit over unilateral device use when noise was ipsilateral to the unilateral device. This was primarily because of monaural head-shadow effects, which resulted in robust SRT improvements (P<0.001) of about 4 to 5 dB when ipsilateral and contralateral noise positions were compared. The additional benefit of using both ears compared to the shadowed ear (i.e., binaural unmasking) was only 1 or 2 dB and less robust (P = 0.04). Results from the lateralization studies showed consistently good sensitivity to ILDs; better than the smallest level adjustment available in the implants (0.17 dB) for some subjects. Sensitivity to ITDs was moderate on the other hand, typically of the order of 100 micros. ITD sensitivity deteriorated rapidly when stimulation rates for unmodulated pulse-trains increased above a few hundred Hz but at 800 pps showed sensitivity comparable to 50-pps pulse-trains when a 50-Hz modulation was applied. In our opinion, these results clearly demonstrate important benefits are available from bilateral implantation, both for localizing sounds (in quiet) and for listening in noise when signal and noise sources are spatially separated. The data do indicate, however, that effects of interaural timing cues are weaker than those from interaural level cues and according to our psychophysical findings rely on the availability of low-rate information below a few hundred Hz.

Effects of slow- and fast-acting compression on the detection of gaps in narrow bands of noise

The inherent amplitude fluctuations in narrow bands of noise may limit the ability to detect gaps in the noise; 'dips' in the noise may be confused with the gap to be detected. For people with cochlear hearing loss, loudness recruitment may effectively magnify the fluctuations and this could partly account for the reduced ability to detect gaps in noise bands that is usually found for such people. Previously, we tested these ideas by processing the envelopes of noise bands to alter the amount of envelope fluctuation. We showed that instantaneous compression, implemented via processing of the Hilbert envelope, led to smaller (that is, better) gap detection thresholds for subjects with cochlear hearing loss. In the present experiment, we determined whether fast-acting compression of the type sometimes used in hearing aids could also lead to improved gap detection. A behind-the-ear (BTE) digital hearing aid was programmed to implement multi-band compression, either fast-acting or slow-acting (control condition). A reference condition using unaided listening was also used. Stimuli were delivered via an earphone placed over the hearing aid. Overall stimulus levels at the output of the hearing aid were similar across conditions. Thresholds for detecting gaps in noise bands centred at 4 kHz were measured as a function of noise bandwidth (10-500 Hz). To prevent the detection of spectral changes introduced by the gap, stimuli were presented in a broad-band background noise. Three normally hearing subjects and three subjects with bilateral cochlear hearing loss were tested. Gap thresholds varied non-monotonically with noise bandwidth, being maximal around 50 Hz. Gap thresholds were generally higher for the hearing-impaired than for the normally hearing subjects. For the latter, gap thresholds were similar for the three conditions. For the hearing-impaired subjects, gap thresholds were similar for the unaided condition and the condition using slow compression. However, fast compression led to smaller gap thresholds, especially for noise bandwidths up to 50 Hz. The results show that fast compression can improve the ability of hearing-impaired subjects to detect gaps in sounds with slowly fluctuating envelopes.

The perception of waning signals: decruitment in loudness and perceived size

When a tone or broad-band noise sweeps smoothly from a moderate intensity to a low one, the loudness at the end of the sweep is far less than what would be predicted from its intensity. The accelerated reduction in loudness, which was first reported by Canévet (1986) and confirmed in several later reports, has been called loudness decruitment, and has been tentatively interpreted as the result of some form of adaptation. Since both simple and induced adaptation have distinctive temporal profiles, we undertook a series of studies in which we varied the duration of a tone whose intensity was continuously changing, to see whether the effect of duration on decruitment resembled the effects of duration on adaptation. We discovered that the magnitude of decruitment remained unaffected when the duration of the sweep was reduced far below the durations of 90 to 180 sec that have been used in previous studies. The same effect was observed for durations of around 20 sec, but it declined rapidly to a low level at the lowest duration of 1.0 sec. This temporal pattern is strikingly different from what has been reported for either simple or ipsilaterally induced adaptation, which suggests that neither form of adaptation can account for the entire effect. We also wanted to know whether an analogous phenomenon could exist for a sensory modality other than hearing. In the present study, observers were asked to judge the apparent size of a solid disk on a computer monitor, the disk increased or decreased continuously in area, or appeared as a series of separate areas, either in random order or in ordered progressions. We found that, as in the case of loudness, apparent size decreased more rapidly when the areas decreased continuously than would have been predicted from the actual areas themselves. We also found that some part of the accelerated shrinkage was due to a response bias in the observers' judgments that stemmed from knowledge that every value in a continuously changing series is predictably smaller (or larger, for a growing series). Whether the remaining part of the effect is a sensory phenomenon is an important issue for future research.

Effect of signal duration on categorical loudness scaling in normal and in hearing-impaired listeners

The present study sought to determine whether the duration of white-noise bursts affects their loudness category rating in the same way for hearing-impaired as for normally-hearing subjects. Twelve normally-hearing and 12 hearing-impaired subjects took part. Categorical loudness growth functions were obtained for 16.25 ms, 32.5 ms, 75 ms, 150 ms and 300 ms white noise bursts. Temporal integration of loudness was defined as the intensity difference needed for stimuli of different durations to result in identical category ratings. In normally-hearing subjects, temporal integration of loudness occurred mainly with the short-duration (16.25 ms and 32.5 ms) stimuli, whereas it was found with almost every stimulus duration in hearing-impaired subjects. In other words, temporal integration of loudness between 16.25 ms and 300 ms stimulus duration was greater in hearing-impaired listeners and there was a difference between normal and hearing-impaired subjects regarding change in loudness perception with stimulus duration. Consequently, the use of fixed-duration stimuli hinders loudness normalization.

Measurements of loudness growth in 1/2-octave bands for children and adults with normal hearing

The loudness growth in 1/2-octave bands (LGOB) procedure has been shown previously to provide valid estimates of loudness growth for adults with normal hearing and those with hearing loss (Allen, Hall, & Jeng, 1990), and it has been widely incorporated into fitting strategies for adult hearing aid users by a hearing aid manufacturer. Here, we applied a simple modification of LGOB to children and adults with normal hearing and then compared the loudness growth functions (as obtained from end-point data) between the two age groups. In addition, reliability data obtained within a single session and between test sessions were compared between the two groups. Large differences were observed in the means between the two groups for the lower boundary values, the upper boundary values, and the range between boundaries both within and across all frequencies. The data obtained from children also had greater variance than the adult data. In addition, there was more variability in the data across test sessions for children. Many test-retest differences for children exceeded 10 dB. Adult test-retest differences were generally less than 10 dB. Although the LGOB with the modifications used in this study may be used to measure loudness growth in children, its poor reliability with this age group may limit its clinical use for children with hearing loss. Additional work is needed to explore whether loudness growth measures can be adapted successfully to children and whether these measures contribute worthwhile information for fitting hearing aids to children.

Temporal loudness integration and spectral loudness summation in normal-hearing and hearing-impaired listeners

The aim of this study was to test for differences between normal-hearing and hearing-impaired listeners regarding two fundamental aspects of intensity perception: loudness integration and loudness summation. Loudness functions for three different stimuli were measured using categorical loudness scaling in 8 normal-hearing and 12 hearing-impaired subjects. The results indicated that temporal loudness integration, defined as the difference in SPL between 16.25-ms and 300-ms noise bursts of equal loudness, was larger in the hearing-impaired than in the normal-hearing listeners. Loudness summation, defined as the difference in SPL between a 300-ms, 1,600-Hz tone pip and a white noise burst of the same duration and loudness, did not differ between the two groups. Implications of these results for hearing aid fitting strategies based on loudness normalization are discussed.

Loudness growth functions and EABR characteristics in Digisonic cochlear implantees

Electrically evoked auditory brainstem responses (EABRs) and loudness functions were measured in 14 subjects equipped with an MXM Digisonic cochlear implant. EABRs were evoked by 75-Hz pulse trains presented on the apical electrode. Loudness functions at the same rate and at a rate more conventional for psychoacoustic measurements (300 Hz) were measured using a categorical loudness-scaling procedure. The results revealed a significant difference in the loudness functions measured at 75 and 300 Hz, loudness increasing more steeply with stimulus intensity for the latter rate. Significant correlations between EABR wave V thresholds and perceptual thresholds measured at both 75 and 300 Hz were observed. Furthermore, in 8 out of the 14 patients, EABR wave V saturated at a stimulus level corresponding precisely to the loudest bearable, i.e. "Too loud" level for the 300-Hz stimulation rate; this same level corresponded to the "Comfortable" loudness level for the 75-Hz stimulation rate. On average, an almost linear relationship was observed over the first half of the loudness range between the stimulus intensity, expressed as a pulse duration in log units, and wave V amplitude in dB. Although further investigation is required before maximum comfort levels can be predicted reliably from EABR measures in individual subjects, these results indicate new directions regarding the estimation of perceptual dynamic range limits on the basis of EABR measures in cochlear implantees.

Effects of amplitude nonlinearity on phoneme recognition by cochlear implant users and normal-hearing listeners

It is widely assumed that the proper transformation of acoustic amplitude to electric amplitude is a critical factor affecting speech recognition in cochlear implant users and normal-hearing listeners. A four-channel noise-band speech processor was implemented, reducing spectral information to four bands. A power-law transformation was applied to the amplitude mapping stage in the speech processor design, and the exponent of the power function varied from a strongly compressive (p = 0.05) to a weakly compressive (p = 0.75) for implant listeners and from 0.3 to 3.0 for acoustic listeners. Results for implants showed that the best performance was achieved with an exponent of about 0.2, and performance gradually deteriorated when either more compressive or less compressive exponents were applied. The loudness growth functions of the four activated electrodes in each subject were measured and those data were well fit by a power function with a mean exponent of 2.72. The results indicated that the best performance was achieved when the normal loudness growth was restored. For acoustic listeners, results were similar to those observed with cochlear implant listeners, except that best performance was achieved with no amplitude nonlinearity (p = 1.0). The similarity of results in both acoustic and electric stimulation indicated that the performance deterioration observed for extreme nonlinearity was due to similar perceptual effects. The function relating amplitude mapping exponent and performance was relatively flat, indicating that phoneme recognition was only mildly affected by amplitude nonlinearity.

Development and evaluation of a procedure for fitting multi-channel compression hearing aids

Hearing aids with multi-channel compression are often fitted on the basis of loudness scaling data obtained using narrow bands of noise or tones. Here, we report the development and evaluation of an alternative fitting procedure based on the use of speech signals. The parameters of the hearing aid (the gains in each channel for high and low input levels) are adjusted adaptively under computer control on the basis of the listener's responses. The goal is that speech at 85 dB SPL should be judged as 'loud', speech at 60 dB SPL should be judged as 'quiet', and speech at both levels should be judged as 'neither tinny nor boomy'. The procedure was evaluated using a two-channel compression hearing aid, the remote control of which allowed two programs to be stored. One program was based on our fitting procedure. The other was either based on the manufacturer's recommended full fitting procedure (which included loudness scaling with bands of noise), or was based on the audiogram alone, using the manufacturer's algorithm. After an acclimatization period of at least two weeks, subjects were then asked to fill in a questionnaire about their experiences with the two programs in different listening situations. The results generally indicated a preference for the program based on our adaptive fitting procedure. We also conducted laboratory measurements of speech intelligibility, in quiet and in a background of a single competing talker. These showed no clear difference between programs, although scores overall were very high. We conclude that our adaptive procedure gives very satisfactory results in everyday life. Parameter values giving good comfort also give good intelligibility. The procedure typically takes between five and 10 minutes per ear, which is quicker than most loudness scaling procedures.

Temporal analysis and stimulus fluctuation in listeners with normal and impaired hearing

The first experiment investigated the effects of mild to moderate sensorineural hearing impairment on temporal analysis for noise stimuli of varying bandwidth. Tasks of temporal gap detection, amplitude modulation (AM) detection, and AM discrimination were examined. Relatively high levels of stimulation were used in order to reduce the possibility that the results of the listeners with hearing impairment would be influenced strongly by audibility. A general summary of results was that there was relatively great interlistener variation among the listeners with hearing impairment, with most listeners showing normal performance and some showing degraded performance, regardless of the bandwidth of the stimulus carrying the temporal information. A second experiment investigated the hypothesis that listeners with sensorineural hearing impairment might have poor gap detection due to loudness recruitment. Here, gap markers were presented at levels where loudness growth was steeper for the listeners with hearing impairment than for the listeners with normal hearing. Although gap detection was sometimes poorer in listeners with hearing impairment than in listeners with normal hearing, there was no clear relation between gap detection performance and loudness recruitment in listeners with mild to moderate sensorineural hearing impairment.

Quinine reduces the dynamic range of the human auditory system

The aim of the study was to evaluate and quantify quinine-induced changes in the human auditory dynamic range, as a model for cochlear hearing loss. Six otologically normal volunteers (21-40 years old) received quinine hydrochloride (15 mg/kg body weight) in two identical oral doses and one intravenous infusion. Refined hearing tests were performed monaurally at threshold, at moderate hearing levels and at high hearing levels. Quinine induced a maximal pure-tone threshold shift of 23 dB (1000-2000 Hz). The increase in the psychoacoustical click threshold agreed with an increase in the detection threshold of click-evoked otoacoustic emissions. The change in the stimulus-response relationship of the emissions reflected recruitment. The self-attained most comfortable speech level and the acoustic stapedius reflex thresholds were not affected by quinine administration. Quinine is a useful model substance for reversibly inducing complete loudness recruitment in humans as it acts specifically on some parts of the hearing function. Its mechanism of action on the molecular level is likely to reveal further information on the physiology of hearing.

Age-related hearing loss: a case for nursing intervention

This review paper selectively examines the problem of age-related hearing loss. Drawing on specialist audiological research, nursing research and patient anecdotes to make a case for nursing intervention. The limitations of national prevalence estimates are highlighted with regard to dependent elderly people, and are challenged as political underestimations of need. Despite the evidence of an exceptionally high level of potential demand only a minority of elderly people who might benefit from amplification possess a hearing aid. Factors to explain the low levels of hearing aid ownership and use are discussed. Through considerable reference to the author's own research the potential for nurses to lead practice developments and initiate service reform in the management of age-related hearing loss is debated.

A compact disc containing simulations of hearing impairment

The author has produced a compact disc (CD) which contains a series of simulations of the effects of cochlear hearing loss. The following aspects are simulated: threshold elevation combined with loudness recruitment; reduced frequency selectivity; and threshold elevation, loudness recruitment and reduced frequency selectivity all together. The effects are demonstrated using speech in quiet and in a background of noise, and using a piece of music with a wide dynamic range. The CD also includes simulations of the effect of having a conventional 'linear' hearing aid, and of having aid incorporating dual-channel fast acting compression. Finally, the CD contains demonstrations of the 'occlusion effect' and the benefits of having a deeply fitting earmould or hearing aid. The purpose of this note is to describe some of the uses of the CD for teaching and educational purposes and to indicate which tracks will be most effective for specific purposes.

Effects of fast-acting high-frequency compression on the intelligibility of speech in steady and fluctuating background sounds

This study examines whether speech intelligibility in background sounds can be improved for persons with loudness recruitment by the use of fast-acting compression applied at high frequencies, when the overall level of the sounds is held constant by means of a slow-acting automatic gain control (AGC) system and when appropriate frequency-response shaping is applied. Two types of fast-acting compression were used in the high-frequency channel of a two-channel system: a compression limiter with a 10:1 compression ratio and with a compression threshold about 9 dB below the peak level of the signal in the high-frequency channel; and a wide dynamic range compressor with a 2:1 compression ratio and with the compression threshold about 24 dB below the peak level of the signal in the high-frequency channel. A condition with linear processing in the high-frequency channel was also used. Speech reception thresholds (SRTs) were measured for two background sounds: a steady speech-shaped noise and a single male talker. All subjects had moderate-to-severe sensorineural hearing loss. Three different types of speech material were used: the adaptive sentence lists (ASL), the Bamford-Kowal-Bench (BKB) sentence lists and the Boothroyd word lists. For the steady background noise, the compression generally led to poorer performance than for the linear condition, although the deleterious effect was only significant for the 10:1 compression ratio. For the background of a single talker, the compression had no significant effect except for the ASL sentences, where the 10:1 compression gave significantly better performance than the linear condition. Overall, the results did not show any clear benefits of the fast-acting compression, possibly because the slow-acting AGC allowed the use of gains in the linear condition that were markedly higher than would normally be used with linear hearing aids.

Comparison of real and simulated hearing impairment in subjects with unilateral and bilateral cochlear hearing loss

Simulations of hearing impairment were presented to the normal ears of subjects with moderate to severe unilateral cochlear hearing loss. The intelligibility of speech in quiet and in background sounds was compared with that obtained for the impaired ears using unprocessed stimuli. The results of loudness matches between the two ears were used to tailor a simulation of threshold elevation combined with loudness recruitment individually for each subject. This was assessed either alone, or in combination with a simulation of reduced frequency selectivity, performed by spectral smearing. Finally, we included a simulation of 'dead' regions in the cochlea, where there are assumed to be no functioning inner hair cells and/or neurones, by band-stop filtering over the frequency range corresponding to the dead region. Performance for the impaired ears was markedly worse than for the normal ears using the simulation of threshold elevation and loudness recruitment. The addition of the simulation of reduced frequency selectivity caused performance to worsen, but it remained above that for the impaired ears. The additional simulation of a dead region had little effect, except for one subject, for whom it produced performance comparable to that for the impaired ear in quiet but not when background sounds were present. It is suggested that the relatively poor results for the impaired ears may be caused partly by a form of 'neglect' which is specific to subjects with unilateral or asymmetric loss. This idea was supported by results obtained using bilaterally hearing-impaired subjects, which were markedly better than for the impaired ears of the unilaterally hearing-impaired subjects, and comparable to those for the normal ears listening to the combined simulation of threshold elevation, loudness recruitment and reduced frequency selectivity.

Simulation of the effect of threshold elevation and loudness recruitment combined with reduced frequency selectivity on the intelligibility of speech in noise

The effect of loudness recruitment and threshold elevation together with reduced frequency selectivity have been simulated to examine the combined effect of the two major consequences of cochlear hearing loss on the intelligibility of speech in speech-shaped noise. In experiment 1, four conditions were simulated: a moderate flat loss with auditory filters broadened by a factor of three (B3R2); a moderate-to-severe sloping loss with auditory filters broadened by a constant factor of three (B3RX); and these conditions with linear amplification applied prior to the simulation processing (B3R2+, B3RX+). For conditions B3R2 and B3RX, performance was markedly worse than for a control condition (normal hearing, condition R1) tested in a previous study. For conditions B3R2+ and B3RX+, linear amplification improved performance considerably. However, performance remained below that for condition R1 by between 5% and 19%. In experiment 2 the broadening of the auditory filters was made more realistic by making it a function of the absolute threshold at the center frequency of the auditory filter. Three different hearing losses were simulated: a moderate-to-severe sloping loss with variable broadening of the auditory filters (BXRX); the same moderate-to-severe sloping loss with linear amplification (BXRX+); and the same broadening of the auditory filters but without the simulation of loudness recruitment and threshold elevation (BX). For condition BXRX, performance was markedly worse than in condition R1, while performance in condition BX was somewhat worse than for condition R1. For condition BXRX+, linear amplification according to the NAL procedure improved performance to a large extent but it remained worse than for condition R1. The results are consistent with previous evidence indicating that only part of the decrease of performance produced by actual cochlear hearing loss can be compensated by conventional linear hearing aids.