142 research outputs found

    Perceptual consequences of "hidden" hearing loss

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    Dramatic results from recent animal experiments show that noise exposure can cause a selective loss of high-threshold auditory nerve fibers without affecting absolute sensitivity permanently. This cochlear neuropathy has been described as hidden hearing loss, as it is not thought to be detectable using standard measures of audiometric threshold. It is possible that hidden hearing loss is a common condition in humans and may underlie some of the perceptual deficits experienced by people with clinically normal hearing. There is some evidence that a history of noise exposure is associated with difficulties in speech discrimination and temporal processing, even in the absence of any audiometric loss. There is also evidence that the tinnitus experienced by listeners with clinically normal hearing is associated with cochlear neuropathy, as measured using Wave I of the auditory brainstem response. To date, however, there has been no direct link made between noise exposure, cochlear neuropathy, and perceptual difficulties. Animal experiments also reveal that the aging process itself, in the absence of significant noise exposure, is associated with loss of auditory nerve fibers. Evidence from human temporal bone studies and auditory brainstem response measures suggests that this form of hidden loss is common in humans and may have perceptual consequences, in particular, regarding the coding of the temporal aspects of sounds. Hidden hearing loss is potentially a major health issue, and investigations are ongoing to identify the causes and consequences of this troubling condition

    Effect of human auditory efferent feedback on cochlear gain and compression

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    The manunalian auditory system includes a brainstem-mediated efferent pathway from the superior olivary complex by way of the medial olivocochlear system, which reduces the cochlear response to sound (Warr and Guinan, 1979; Liberman et al., 1996). The human medial olivocochlear response has an onset delay of between 25 and 40 ms and rise and decay constants in the region of 280 and 160 ms, respectively (Backus and Guinan, 2006). Physiological studies with nonhuman mammals indicate that onset and decay characteristics of efferent activation are dependent on the temporal and level characteristics of the auditory stimulus (Bacon and Smith, 1991; Guinan and Stankovic, 1996). This study uses a novel psychoacoustical masking technique using a precursor sound to obtain a measure of the efferent effect in humans. This technique avoids confounds currently associated with other psychoacoustical measures. Both temporal and level dependency of the efferent effect was measured, providing a comprehensive measure of the effect of human auditory efferents on cochlear gain and compression. Results indicate that a precursor (>20 dB SPL) induced efferent activation, resulting in a decrease in both maximum gain and maximum compression, with linearization of the compressive function for input sound levels between 50 and 70 dB SPL. Estimated gain decreased as precursor level increased, and increased as the silent interval between the precursor and combined masker-signal stimulus increased, consistent with a decay of the efferent effect Human auditory efferent activation linearizes the cochlear response for mid-level sounds while reducing maximum gain

    Identifying Targets for Interventions to Increase Uptake and Use of Hearing Protection in Noisy Recreational Settings

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    From MDPI via Jisc Publications RouterHistory: accepted 2021-07-26, pub-electronic 2021-07-29Publication status: PublishedFunder: Manchester Biomedical Research Centre; Grant(s): UnknownInterventions to increase hearing protection behaviours within noisy recreational settings are limited by the lack of an underpinning evidence base. The aim of the present study was to identify targets for interventions in a population exposed to recreational noise, including those who had used hearing protection (ever-performers) versus those who had not (never-performers). A cross-sectional survey was administered to 185 UK adults who had been involved in noisy recreational activities. Participants had an average age of 36.79 years; the majority were women (68.1%), from a white ethnic background (87.6%), and with non-manual occupations (75.7%). Using Chi-square, MANOVA and ANOVA, we looked for differences in sociodemographic variables and variables from the capabilities, opportunities and motivations model of behaviour change (COM-B) between ever- and never-performers. Ever-performers were more likely to be younger (p 0.050), men (p 0.050), and in a manual occupation (p 0.050) compared to never-performers. Although the two groups felt capable and reported similar opportunities to use hearing protection, never-performers lacked automatic motivation (p 0.001) and reflective motivation (p 0.001) compared to ever-performers. For the first time, the present study identifies potential groups at whom hearing protection interventions might be targeted and what those interventions may contain. Further work is required to develop interventions targeted at older people, women and those in non-manual occupations. Lack of motivation is a key concern, and further work that uses specific theoretical frameworks, such as the PRIME (Plans, Responses, Impulses, Motives, and Evaluations) theory of motivation, may shed light on the kinds of interventions that are needed to boost hearing protection use effectively

    Specificity of the human frequency following response for carrier and modulation frequency assessed using adaptation

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    The frequency following response (FFR) is a scalp-recorded measure of phase-locked brainstem activity to stimulus-related periodicities. Three experiments investigated the specificity of the FFR for carrier and modulation frequency using adaptation. FFR waveforms evoked by alternating-polarity stimuli were averaged for each polarity and added, to enhance envelope, or subtracted, to enhance temporal fine structure information. The first experiment investigated peristimulus adaptation of the FFR for pure and complex tones as a function of stimulus frequency and fundamental frequency (F0). It showed more adaptation of the FFR in response to sounds with higher frequencies or F0s than to sounds with lower frequency or F0s. The second experiment investigated tuning to modulation rate in the FFR. The FFR to a complex tone with a modulation rate of 213 Hz was not reduced more by an adaptor that had the same modulation rate than by an adaptor with a different modulation rate (90 or 504 Hz), thus providing no evidence that the FFR originates mainly from neurons that respond selectively to the modulation rate of the stimulus. The third experiment investigated tuning to audio frequency in the FFR using pure tones. An adaptor that had the same frequency as the target (213 or 504 Hz) did not generally reduce the FFR to the target more than an adaptor that differed in frequency (by 1.24 octaves). Thus, there was no evidence that the FFR originated mainly from neurons tuned to the frequency of the target. Instead, the results are consistent with the suggestion that the FFR for low-frequency pure tones at medium to high levels mainly originates from neurons tuned to higher frequencies. Implications for the use and interpretation of the FFR are discussed

    Which interventions increase hearing protection behaviors during noisy recreational activities? A systematic review

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    From Springer Nature via Jisc Publications RouterHistory: received 2020-02-10, accepted 2020-08-19, registration 2020-08-20, pub-electronic 2020-09-13, online 2020-09-13, collection 2020-12Publication status: PublishedFunder: Manchester Biomedical Research Centre; doi: http://dx.doi.org/10.13039/100014653; Grant(s): N/AAbstract: Background: Hearing loss and tinnitus are global concerns that can be reduced through hearing protection behaviors (e.g., earplug use). Little is known about the effectiveness of interventions to increase hearing protection use in recreational domains. For the first time we review systematically the effectiveness of such interventions. Methods: Systematic searches of nine databases, as well as grey literature and hand-searching, were conducted. Any study design was included if it assessed quantitatively a purposeful attempt to increase hearing protection in recreational settings. Studies were excluded if they assessed noise exposure from occupational sources and headphones/earphones, as these have been reviewed elsewhere. PROSPERO protocol: CRD42018098573. Results: Eight studies were retrieved following the screening of 1908 articles. Two pretest-posttest studies detected a small to medium effect (d ≥ 0·3 ≤ 0·5), one a small effect (d ~ =0·2) and two no real effect. Three posttest experimental studies detected small to medium effects (d ≥ 0·3 ≤ 0·5). Studies were rated as “poor quality” and 17 out of a possible 93 behavior change techniques were coded, with the majority targeting the intervention function ‘education’. Conclusions: Hearing loss and tinnitus due to recreational noise exposure are major public health concerns yet very few studies have examined preventive interventions. The present systematic review sets the agenda for the future development and testing of evidence-based interventions designed to prevent future hearing loss and tinnitus caused by noise in recreational settings, by recommending systematic approaches to intervention design, and implementation of intervention functions beyond education, such as incentivization, enablement and modeling

    Identifying Targets for Interventions to Increase Earplug Use in Noisy Recreational Settings: A Qualitative Interview Study

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    From MDPI via Jisc Publications RouterHistory: accepted 2021-12-04, pub-electronic 2021-12-07Publication status: PublishedFunder: NIHR Manchester Biomedical Research Centre; Grant(s): IS-BRC-1215-20007Earplugs can reduce the risk of hearing loss and tinnitus. However, earplug use during noisy recreational activities is uncommon, and methods for increasing uptake and regular use have had limited efficacy. The aim of the present study was to examine barriers and enablers of ever-performers (e.g., people who have used earplugs) and never-performers (e.g., people who have not used earplugs) to identify targets to inform the content of interventions to increase uptake and regular use of earplugs in recreational settings. The Capabilities, Opportunities, and Motivations model of Behaviour (COM-B) informed the outline for 20 semi-structured telephone interviews (ever-performers, N = 8, age range = 20−45 years; never-performers, N = 12; age range = 20−50 years). Thematic analysis was used to identify barriers and enablers to earplug use, which were mapped onto the Theoretical Domains Framework (TDF). Six key domains of the TDF were identified. Ever-performers described being more exposed to ‘social influences’ (e.g., facilitators such as friends/peers) and were more positive than never-performers concerning ‘beliefs about consequences’ (e.g., earplug protection outweighs any negative effects on listening/communication). Involvement of ‘emotion’ (e.g., fear of losing ability to listen to music) and ‘reinforcement’ tactics (e.g., creating habits/routines) were discussed by ever-performers, but were not mentioned by never-performers. Both groups reported lack of ‘environmental context and resources’ (e.g., prompts and cues), and their own ‘memory, attention, and decision processes’ (e.g., deciding when to use earplugs) as barriers to earplug use. The present research identifies the variables that would need to change in order to increase earplug uptake and use in recreational settings among ever-performers and never-performers. Further work is required to translate these findings into testable interventions by selecting appropriate intervention functions (e.g., modelling), policy categories (e.g., communication/marketing), behaviour change techniques (e.g., demonstration of behaviour), and mode of delivery (e.g., face-to-face)

    Cochlear nonlinearity between 500 and 8000 Hz in listeners with normal hearing

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    Cochlear nonlinearity was estimated over a wide range of center frequencies and levels in listeners with normal hearing, using a forward-masking method. For a fixed low-level probe, the masker level required to mask the probe was measured as a function of the masker-probe interval, to produce a temporal masking curve ͑TMC͒. TMCs were measured for probe frequencies of 500, 1000, 2000, 4000, and 8000 Hz, and for masker frequencies 0.5, 0.7, 0.9, 1.0 ͑on frequency͒, 1.1, and 1.6 times the probe frequency. Across the range of probe frequencies, the TMCs for on-frequency maskers showed two or three segments with clearly distinct slopes. If it is assumed that the rate of decay of the internal effect of the masker is constant across level and frequency, the variations in the slopes of the TMCs can be attributed to variations in cochlear compression. Compression-ratio estimates for on-frequency maskers were between 3:1 and 5:1 across the range of probe frequencies. Compression did not decrease at low frequencies. The slopes of the TMCs for the lowest frequency probe ͑500 Hz͒ did not change with masker frequency. This suggests that compression extends over a wide range of stimulus frequencies relative to characteristic frequency in the apical region of the cochlea

    Cochlear nonlinearity between 500 and 8000 Hz in listeners with normal hearing

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    Cochlear nonlinearity was estimated over a wide range of center frequencies and levels in listeners with normal hearing, using a forward-masking method. For a fixed low-level probe, the masker level required to mask the probe was measured as a function of the masker-probe interval, to produce a temporal masking curve ͑TMC͒. TMCs were measured for probe frequencies of 500, 1000, 2000, 4000, and 8000 Hz, and for masker frequencies 0.5, 0.7, 0.9, 1.0 ͑on frequency͒, 1.1, and 1.6 times the probe frequency. Across the range of probe frequencies, the TMCs for on-frequency maskers showed two or three segments with clearly distinct slopes. If it is assumed that the rate of decay of the internal effect of the masker is constant across level and frequency, the variations in the slopes of the TMCs can be attributed to variations in cochlear compression. Compression-ratio estimates for on-frequency maskers were between 3:1 and 5:1 across the range of probe frequencies. Compression did not decrease at low frequencies. The slopes of the TMCs for the lowest frequency probe ͑500 Hz͒ did not change with masker frequency. This suggests that compression extends over a wide range of stimulus frequencies relative to characteristic frequency in the apical region of the cochlea

    Consonance perception beyond the traditional existence region of pitch

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    Some theories posit that the perception of consonance is based on neural periodicity detection, which is dependent on accurate phase locking of auditory nerve fibers to features of the stimulus waveform. In the current study, 15 listeners were asked to rate the pleasantness of complex tone dyads (2 note chords) forming various harmonic intervals and bandpass filtered in a high-frequency region (all components >5.8 kHz), where phase locking to the rapid stimulus fine structure is thought to be severely degraded or absent. The two notes were presented to opposite ears. Consonant intervals (minor third and perfect fifth) received higher ratings than dissonant intervals (minor second and tritone). The results could not be explained in terms of phase locking to the slower waveform envelope because the preference for consonant intervals was higher when the stimuli were harmonic, compared to a condition in which they were made inharmonic by shifting their component frequencies by a constant offset, so as to preserve their envelope periodicity. Overall the results indicate that, if phase locking is indeed absent at frequencies greater than ∼5 kHz, neural periodicity detection is not necessary for the perception of consonance

    The human 'pitch center' responds differently to iterated noise and Huggins pitch

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    A magnetoencephalographic marker for pitch analysis (the pitch onset response) has been reported for different types of pitch-evoking stimuli, irrespective of whether the acoustic cues for pitch are monaurally or binaurally produced. It is claimed that the pitch onset response reflects a common cortical representation for pitch, putatively in lateral Heschl's gyrus. The result of this functional MRI study sheds doubt on this assertion. We report a direct comparison between iterated ripple noise and Huggins pitch in which we reveal a different pattern of auditory cortical activation associated with each pitch stimulus, even when individual variability in structure-function relations is accounted for. Our results suggest it may be premature to assume that lateral Heschl's gyrus is a universal pitch center
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