Hidden Hearing Loss? No Effect of Common Recreational Noise Exposure on Cochlear Nerve Response Amplitude in Humans

Recent studies demonstrated that reversible continuous noise exposure may induce a temporary threshold shift (TTS) with a permanent degeneration of auditory nerve fibers, although hair cells remain intact. To probe the impact of TTS-inducing impulse noise exposure on hearing, CBA/J Mice were exposed to noise impulses with peak pressures of 145 dB SPL. We found that 30 min after exposure, the noise caused a mean elevation of ABR thresholds of ~30 dB and a reduction in DPOAE amplitude. Four weeks later, ABR thresholds and DPOAE amplitude were back to normal in the higher frequency region (8–32 kHz). At lower frequencies, a small degree of PTS remained. Morphological evaluations revealed a disturbance of the stereociliary bundle of outer hair cells, mainly located in the apical regions. On the other hand, the reduced suprathreshold ABR amplitudes remained until 4 weeks later. A loss of synapse numbers was observed 24 h after exposure, with full recovery two weeks later. Transmission electron microscopy revealed morphological changes at the ribbon synapses by two weeks post exposure. In addition, increased levels of oxidative stress were observed immediately after exposure, and maintained for a further 2 weeks. These results clarify the pathology underlying impulse noise-induced sensory dysfunction, and suggest possible links between impulse-noise injury, cochlear cell morphology, metabolic changes, and hidden hearing loss.

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The Physiological Bases of Hidden Noise-Induced Hearing Loss: Protocol for a Functional Neuroimaging Study (Preprint)

10.2196/preprints.9095 ◽

2017 ◽

Author(s):

Rebecca Susan Dewey ◽

Deborah A Hall ◽

Hannah Guest ◽

Garreth Prendergast ◽

Christopher J Plack ◽

...

Keyword(s):

Hearing Loss ◽

Noise Exposure ◽

Functional Neuroimaging ◽

Nerve Fibers ◽

High Threshold ◽

Hearing Level ◽

Noise Induced Hearing Loss ◽

Brainstem Response ◽

Neuroimaging Study ◽

Hidden Hearing Loss

BACKGROUND Rodent studies indicate that noise exposure can cause permanent damage to synapses between inner hair cells and high-threshold auditory nerve fibers, without permanently altering threshold sensitivity. These demonstrations of what is commonly known as hidden hearing loss have been confirmed in several rodent species, but the implications for human hearing are unclear. OBJECTIVE Our Medical Research Council–funded program aims to address this unanswered question, by investigating functional consequences of the damage to the human peripheral and central auditory nervous system that results from cumulative lifetime noise exposure. Behavioral and neuroimaging techniques are being used in a series of parallel studies aimed at detecting hidden hearing loss in humans. The planned neuroimaging study aims to (1) identify central auditory biomarkers associated with hidden hearing loss; (2) investigate whether there are any additive contributions from tinnitus or diminished sound tolerance, which are often comorbid with hearing problems; and (3) explore the relation between subcortical functional magnetic resonance imaging (fMRI) measures and the auditory brainstem response (ABR). METHODS Individuals aged 25 to 40 years with pure tone hearing thresholds ≤20 dB hearing level over the range 500 Hz to 8 kHz and no contraindications for MRI or signs of ear disease will be recruited into the study. Lifetime noise exposure will be estimated using an in-depth structured interview. Auditory responses throughout the central auditory system will be recorded using ABR and fMRI. Analyses will focus predominantly on correlations between lifetime noise exposure and auditory response characteristics. RESULTS This paper reports the study protocol. The funding was awarded in July 2013. Enrollment for the study described in this protocol commenced in February 2017 and was completed in December 2017. Results are expected in 2018. CONCLUSIONS This challenging and comprehensive study will have the potential to impact diagnostic procedures for hidden hearing loss, enabling early identification of noise-induced auditory damage via the detection of changes in central auditory processing. Consequently, this will generate the opportunity to give personalized advice regarding provision of ear defense and monitoring of further damage, thus reducing the incidence of noise-induced hearing loss.

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Hidden hearing loss is associated with loss of ribbon synapses of cochlea inner hair cells

Bioscience Reports ◽

10.1042/bsr20201637 ◽

2021 ◽

Author(s):

Feng Song ◽

Bin Gan ◽

Na Wang ◽

Zhe Wang ◽

An-ting Xu

Keyword(s):

Hearing Loss ◽

Hair Cell ◽

Noise Exposure ◽

Repeated Exposure ◽

Ribbon Synapse ◽

Intensity Noise ◽

Auditory Function ◽

Ribbon Synapses ◽

Brainstem Response ◽

Hidden Hearing Loss

This study aimed to observe the changes in the cochlea ribbon synapses after repeated exposure to moderate-to-high intensity noise. Guinea pigs received 95 dB SPL white noise exposure 4 hours a day for consecutive 7 days (we regarded it a medium-term and moderate-intensity noise, or MTMI noise). Animals were divided into 4 groups: Control, 1DPN (1-day post noise), 1WPN (1-week post noise), and 1MPN (1-month post noise). Auditory function analysis by ABR and CAP recordings, as well as ribbon synapse morphological analyses by immunohistochemistry (Ctbp2 and PSD95 staining) were performed one day, one week, and one month after noise exposure. After MTMI noise exposure, the amplitudes of auditory brainstem response (ABR) I and III waves were suppressed. The compound action potential (CAP) threshold was elevated, and CAP amplitude was reduced in the 1DPN group. No apparent changes in hair cell shape, arrangement or number were observed, but the number of ribbon synapse was reduced. The 1WPN and 1MPN groups showed that part of ABR and CAP changes recovered, as well as the synapse number. The defects in cochlea auditory function and synapse changes were observed mainly in the high-frequency region. Together, repeated exposure in MTMI noise can cause hidden hearing loss, which is partially reversible after leaving the noise environment; and MTMI noise induced hidden hearing loss is associated with inner hair cell ribbon synapses.

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Morphology Changes in the Cochlea of Impulse Noiseinduced Hidden Hearing Loss

10.21203/rs.3.rs-961609/v1 ◽

2021 ◽

Author(s):

Guo-wei Qi ◽

Lei Shi ◽

Han-dai Qin ◽

Yuhua Zhu ◽

Qing-qing Jiang ◽

...

Keyword(s):

Hearing Loss ◽

Guinea Pigs ◽

Impulse Noise ◽

Noise Exposure ◽

Nerve Fibers ◽

Basement Membranes ◽

Time Interval ◽

Noise Induced Hearing Loss ◽

Hidden Hearing Loss ◽

Morphology Changes

Abstract Objectives: This study was designed to determine the morphology changes of noise-induced hidden hearing loss (NIHHL). Method: Fifteen guinea pigs were divided into three groups: noise-induced hidden hearing loss (NIHHL) group, noise-induced hearing loss (NIHL) group, and normal control group. For the noise-induced hidden hearing loss group, the guinea pigs were exposed to 15 times of impulse noise at one time. For the noise-induced hearing loss group, the animals were exposed to a total of 200 times of impulse noise in two times, and the time interval is 24 hours. Auditory brain response (ABR) was tested before, immediately, 24h, 1week, and one month after noise exposure to evaluate cochlear physiology changes. One month after noise exposure, all guinea pigs in three groups were sacrificed, and basement membranes were carefully dissected immediately after ABR tests. The cochlea samples were observed by transmission electron microscopy (TEM) to found out the monograph changes. Result: The ABR results showed that 15 times of impulse noise exposure could cause NIHHL in guinea pigs and 200 times could cause completely hearing loss. Impulse noise exposure could cause a dramatic increase in chondriosome in the inner hair cell. The structures of ribbon synapses and heminodes were also obviously impaired compared to the normal group. The nerve fibers and myelin sheaths remained intact after impulse noise exposure. Conclusion: This research revealed for the first time that impulse noise could cause hidden hearing loss, and the changes in inner hair cells, ribbon synapse, and heminode all played a vital role in the pathogenesis of hidden hearing loss.

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Hot Topics—Hidden hearing loss: Permanent cochlear-nerve degeneration after temporary noise-induced threshold shift

The Journal of the Acoustical Society of America ◽

10.1121/1.4877618 ◽

2014 ◽

Vol 135 (4) ◽

pp. 2311-2311 ◽

Cited By ~ 6

Author(s):

M. Charles Liberman ◽

Sharon G. Kujawa

Keyword(s):

Hearing Loss ◽

Cochlear Nerve ◽

Threshold Shift ◽

Nerve Degeneration ◽

Hidden Hearing Loss

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Cochlear Synaptopathy and Noise-Induced Hidden Hearing Loss

Neural Plasticity ◽

10.1155/2016/6143164 ◽

2016 ◽

Vol 2016 ◽

pp. 1-9 ◽

Cited By ~ 23

Author(s):

Lijuan Shi ◽

Ying Chang ◽

Xiaowei Li ◽

Steve Aiken ◽

Lijie Liu ◽

...

Keyword(s):

Hearing Loss ◽

Noise Exposure ◽

Human Subjects ◽

Spiral Ganglion ◽

Nerve Fibers ◽

Type I ◽

Functional Deficits ◽

Ganglion Neurons ◽

Hidden Hearing Loss ◽

Signal Coding

Recent studies on animal models have shown that noise exposure that does not lead to permanent threshold shift (PTS) can cause considerable damage around the synapses between inner hair cells (IHCs) and type-I afferent auditory nerve fibers (ANFs). Disruption of these synapses not only disables the innervated ANFs but also results in the slow degeneration of spiral ganglion neurons if the synapses are not reestablished. Such a loss of ANFs should result in signal coding deficits, which are exacerbated by the bias of the damage toward synapses connecting low-spontaneous-rate (SR) ANFs, which are known to be vital for signal coding in noisy background. As there is no PTS, these functional deficits cannot be detected using routine audiological evaluations and may be unknown to subjects who have them. Such functional deficits in hearing without changes in sensitivity are generally called “noise-induced hidden hearing loss (NIHHL).” Here, we provide a brief review to address several critical issues related to NIHHL: (1) the mechanism of noise induced synaptic damage, (2) reversibility of the synaptic damage, (3) the functional deficits as the nature of NIHHL in animal studies, (4) evidence of NIHHL in human subjects, and (5) peripheral and central contribution of NIHHL.

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