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Trends in Hearing 2023Bone conduction (BC) stimulation has mainly been used for clinical hearing assessment and hearing aids where stimulation is applied at the mastoid behind the ear....
Bone conduction (BC) stimulation has mainly been used for clinical hearing assessment and hearing aids where stimulation is applied at the mastoid behind the ear. Recently, BC has become popular for communication headsets where the stimulation position often is close to the anterior part of the ear canal opening. The BC sound transmission for this stimulation position is here investigated in 21 participants by ear canal sound pressure measurements and hearing threshold assessment as well as simulations in the LiUHead. The results indicated that a stimulation position close to the ear canal opening improves the sensitivity for BC sound by around 20 dB but by up to 40 dB at some frequencies. The transcranial transmission ranges typically between -40 and -25 dB. This decreased transcranial transmission facilitates saliency of binaural cues and implies that BC headsets are suitable for virtual and augmented reality applications. The findings suggest that with BC stimulation close to the ear canal opening, the sound pressure in the ear canal dominates the perception of BC sound. With this stimulation, the ear canal pathway was estimated to be around 25 dB greater than other contributors, like skull bone vibrations, for hearing BC sound in a healthy ear. This increased contribution from the ear canal sound pressure to BC hearing means that a position close to the ear canal is not appropriate for clinical use since, in such case, a conductive hearing loss affects BC and air conduction thresholds by a similar amount.
Topics: Humans; Bone Conduction; Acoustic Stimulation; Auditory Threshold; Hearing; Sound
PubMed: 37083055
DOI: 10.1177/23312165231168741 -
Biomedical Engineering Online Jan 2021An electrical potential not previously reported-electrical cochlear response (ECR)-observed only in implanted patients is described. Its amplitude and growth slope are a...
BACKGROUND
An electrical potential not previously reported-electrical cochlear response (ECR)-observed only in implanted patients is described. Its amplitude and growth slope are a measurement of the stimulation achieved by a tone pip on the auditory nerve. The stimulation and recording system constructed for this purpose, the features of this potential obtained in a group of 43 children, and its possible clinical use are described. The ECR is obtained by averaging the EEG epochs acquired each time the cochlear implant (CI) processes a tone pip of known frequency and intensity when the patient is sleeping and using the CI in everyday mode. The ECR is sensitive to tone pip intensity level, microphone sensitivity, sound processor gain, dynamic range of electrical current, and responsiveness to electrical current of the auditory nerve portion involved with the electrode under test. It allows individual evaluation of intracochlear electrodes by choosing, one at the time, the central frequency of the electrode as the test tone pip frequency, so the ECR measurement due to a variable intensity tone pip allows to establish the suitability of the dynamic range of the electrode current.
RESULTS
There is a difference in ECR measurements when patients are grouped based on their auditory behavior. The ECR slope and amplitude for the Sensitive group is 0.2 μV/dB and 10 μV at 50 dB compared with 0.04 μV/dB and 3 μV at 50dB for the Inconsistent group. The clinical cases show that adjusting the dynamic range of current based on the ECR improved the patient's auditory behavior.
CONCLUSIONS
ECR can be recorded regardless of the artifact due to the electromyographic activity of the patient and the functioning of the CI. Its amplitude and growth slope versus the intensity of the stimulus differs between electrodes. The relationship between minimum ECR detection intensity level and auditory threshold suggests the possibility of estimating patient auditory thresholds this way. ECR does not depend on the subject's age, cooperation, or health status. It can be obtained at any time after implant surgery and the test procedure is the same regardless of device manufacturer.
Topics: Auditory Threshold; Child; Cochlear Implants; Cochlear Nerve; Evoked Potentials, Auditory; Female; Humans; Male
PubMed: 33446195
DOI: 10.1186/s12938-020-00844-6 -
Hearing Research Mar 2024Hearing loss affects approximately 18% of the population worldwide. Hearing difficulties in noisy environments without accompanying audiometric threshold shifts likely... (Review)
Review
Hearing loss affects approximately 18% of the population worldwide. Hearing difficulties in noisy environments without accompanying audiometric threshold shifts likely affect an even larger percentage of the global population. One of the potential causes of hidden hearing loss is cochlear synaptopathy, the loss of synapses between inner hair cells (IHC) and auditory nerve fibers (ANF). These synapses are the most vulnerable structures in the cochlea to noise exposure or aging. The loss of synapses causes auditory deafferentation, i.e., the loss of auditory afferent information, whose downstream effect is the loss of information that is sent to higher-order auditory processing stages. Understanding the physiological and perceptual effects of this early auditory deafferentation might inform interventions to prevent later, more severe hearing loss. In the past decade, a large body of work has been devoted to better understand hidden hearing loss, including the causes of hidden hearing loss, their corresponding impact on the auditory pathway, and the use of auditory physiological measures for clinical diagnosis of auditory deafferentation. This review synthesizes the findings from studies in humans and animals to answer some of the key questions in the field, and it points to gaps in knowledge that warrant more investigation. Specifically, recent studies suggest that some electrophysiological measures have the potential to function as indicators of hidden hearing loss in humans, but more research is needed for these measures to be included as part of a clinical test battery.
Topics: Animals; Humans; Hearing Loss, Noise-Induced; Noise; Auditory Threshold; Hearing Loss, Hidden; Auditory Perception; Cochlea; Synapses; Evoked Potentials, Auditory, Brain Stem
PubMed: 38335624
DOI: 10.1016/j.heares.2024.108967 -
Neurobiology of Disease Mar 2023Several studies identified noise-induced hearing loss (NIHL) as a risk factor for sensory aging and cognitive decline processes, including neurodegenerative diseases,...
Several studies identified noise-induced hearing loss (NIHL) as a risk factor for sensory aging and cognitive decline processes, including neurodegenerative diseases, such as dementia and age-related hearing loss (ARHL). Although the association between noise- and age-induced hearing impairment has been widely documented by epidemiological and experimental studies, the molecular mechanisms underlying this association are not fully understood as it is not known how these risk factors (aging and noise) can interact, affecting memory processes. We recently found that early noise exposure in an established animal model of ARHL (C57BL/6 mice) accelerates the onset of age-related cochlear dysfunctions. Here, we extended our previous data by investigating what happens in central brain structures (auditory cortex and hippocampus), to assess the relationship between hearing and memory impairment and the possible combined effect of noise and sensory aging on the cognitive domain. To this aim, we exposed juvenile C57BL/6 mice of 2 months of age to repeated noise sessions (60 min/day, pure tone of 100 dB SPL, 10 kHz, 10 consecutive days) and we monitored auditory threshold by measuring auditory brainstem responses (ABR), spatial working memory, by using the Y-maze test, and basal synaptic transmission by using ex vivo electrophysiological recordings, at different time points (1, 4 and 7 months after the onset of noise exposure, corresponding to 3, 6 and 9 months of age). We found that hearing loss, along with accelerated presbycusis onset, can induce persistent synaptic alterations in the auditory cortex. This was associated with decreased memory performance and oxidative-inflammatory injury in the hippocampus, the extra-auditory structure involved in memory processes. Collectively, our data confirm the critical relationship between auditory and memory circuits, suggesting that the combined detrimental effect of noise and sensory aging on hearing function can be considered a high-risk factor for both sensory and cognitive degenerative processes, given that early noise exposure accelerates presbycusis phenotype and induces hippocampal-dependent memory dysfunctions.
Topics: Mice; Animals; Presbycusis; Mice, Inbred C57BL; Hippocampus; Auditory Threshold; Memory Disorders; Memory, Short-Term; Evoked Potentials, Auditory, Brain Stem
PubMed: 36724860
DOI: 10.1016/j.nbd.2023.106024 -
Experimental Brain Research Jun 2019Music practice is a multisensory training that is of great interest to neuroscientists because of its implications for neural plasticity. Music-related modulation of...
Music practice is a multisensory training that is of great interest to neuroscientists because of its implications for neural plasticity. Music-related modulation of sensory systems has been observed in neuroimaging data, and has been supported by results in behavioral tasks. Some studies have shown that musicians react faster than non-musicians to visual, tactile and auditory stimuli. Behavioral enhancement in more complex tasks has received considerably less attention in musicians. This study aims to investigate unisensory and multisensory discrimination capabilities in musicians. More specifically, the goal of this study is to examine auditory, tactile and auditory-tactile discrimination in musicians. The literature suggesting better auditory and auditory-tactile discrimination in musicians is scarce, and no study to date has examined pure tactile discrimination capabilities in musicians. A two-alternative forced-choice frequency discrimination task was used in this experiment. The task was inspired by musical production, and participants were asked to identify whether a frequency was the same as or different than a standard stimulus of 160 Hz in three conditions: auditory only, auditory-tactile only and tactile only. Three waveforms were used to replicate the variability of pitch that can be found in music. Stimuli were presented through headphones for auditory stimulation and a glove with haptic audio exciters for tactile stimulation. Results suggest that musicians have lower discrimination thresholds than non-musicians for auditory-only and auditory-tactile conditions for all waveforms. The results also revealed that musicians have lower discrimination thresholds than non-musicians in the tactile condition for sine and square waveforms. Taken together, these results support the hypothesis that musical training can lead to better unisensory tactile discrimination which is in itself a new and major finding.
Topics: Adult; Auditory Perception; Auditory Threshold; Discrimination, Psychological; Female; Humans; Male; Middle Aged; Music; Neuronal Plasticity; Sensory Thresholds; Touch Perception; Young Adult
PubMed: 30927044
DOI: 10.1007/s00221-019-05532-z -
Ear and Hearing 2022Despite a diagnosis of normal hearing, many people experience hearing disability (HD) in their everyday lives. This study assessed the ability of a number of demographic...
OBJECTIVES
Despite a diagnosis of normal hearing, many people experience hearing disability (HD) in their everyday lives. This study assessed the ability of a number of demographic and auditory variables to explain and predict self-reported HD in people regarded as audiologically healthy via audiometric thresholds.
DESIGN
One-hundred eleven adults (ages 19 to 74) with clinically normal hearing (i.e., audiometric thresholds ≤25 dB HL at all octave and interoctave frequencies between 0.25 and 8 kHz and bilaterally symmetric hearing) were asked to complete the 12-item version of the Speech, Spatial, and Qualities of Hearing Scale (SSQ12) as a measure of self-reported HD. Patient history and a number of standard and expanded measures of hearing were assessed in a multivariate regression analysis to predict SSQ12 score. Patient history included age, sex, history of noise exposure, and tinnitus. Hearing-related measures included audiometry at standard and extended high frequencies, word recognition, otoacoustic emissions, auditory brainstem response, the Montreal Cognitive Assessment, and FM detection threshold.
RESULTS
History of impulse noise exposure, speech-intelligibility index, and FM detection threshold accurately predicted SSQ12 and were able to account for 40% of the SSQ12 score. These three measures were also able to predict whether participants self-reported HD with a sensitivity of 89% and specificity of 86%.
CONCLUSIONS
Although participant audiometric thresholds were within normal limits, higher thresholds, history of impulse noise exposure, and FM detection predicted self-reported HD.
Topics: Adult; Aged; Audiometry; Audiometry, Pure-Tone; Auditory Threshold; Hearing; Humans; Middle Aged; Otoacoustic Emissions, Spontaneous; Self Report; Young Adult
PubMed: 34759207
DOI: 10.1097/AUD.0000000000001161 -
Otology & Neurotology : Official... Sep 2016In humans, the accepted clinical standards for detecting hearing loss are the behavioral audiogram, based on the absolute detection threshold of pure-tones, and the... (Review)
Review
OBJECTIVE
In humans, the accepted clinical standards for detecting hearing loss are the behavioral audiogram, based on the absolute detection threshold of pure-tones, and the threshold auditory brainstem response (ABR). The audiogram and the threshold ABR are reliable and sensitive measures of hearing thresholds in human listeners. However, recent results from noise-exposed animals demonstrate that noise exposure can cause substantial neurodegeneration in the peripheral auditory system without degrading pure-tone audiometric thresholds. It has been suggested that clinical measures of auditory performance conducted with stimuli presented above the detection threshold may be more sensitive than the behavioral audiogram in detecting early-stage noise-induced hearing loss in listeners with audiometric thresholds within normal limits.
METHODS
Supra-threshold speech-in-noise testing and supra-threshold ABR responses are reviewed here, given that they may be useful supplements to the behavioral audiogram for assessment of possible neurodegeneration in noise-exposed listeners.
CONCLUSION
Supra-threshold tests may be useful for assessing the effects of noise on the human inner ear, and the effectiveness of interventions designed to prevent noise trauma. The current state of the science does not necessarily allow us to define a single set of best practice protocols. Nonetheless, we encourage investigators to incorporate these metrics into test batteries when feasible, with an effort to standardize procedures to the greatest extent possible as new reports emerge.
Topics: Auditory Threshold; Evoked Potentials, Auditory; Evoked Potentials, Auditory, Brain Stem; Female; Hearing Loss, Noise-Induced; Humans; Male
PubMed: 27518138
DOI: 10.1097/MAO.0000000000001069 -
Otolaryngologic Clinics of North America Apr 2019A new category of hearing technology has emerged that comprises devices inserted deep into the ear canal. Although not implanted, they represent an extension of what is... (Review)
Review
A new category of hearing technology has emerged that comprises devices inserted deep into the ear canal. Although not implanted, they represent an extension of what is expected of a traditional hearing aid. There are advantages to these devices, but they are not suited for all individuals with hearing loss. This category consists of 2 devices currently available in the United States: Lyric (Phonak AG, Stafa, Switzerland) and Earlens (Earlens, Menlo Park, CA, USA).
Topics: Auditory Threshold; Hearing Aids; Hearing Loss, Sensorineural; Hearing Tests; Humans; Patient Satisfaction; Prosthesis Design; Prosthesis Fitting; Speech Perception
PubMed: 30612755
DOI: 10.1016/j.otc.2018.11.003 -
Pain Apr 2023Complex regional pain syndrome (CRPS) is often associated with reduced sound tolerance (hyperacusis) on the affected side, but the mechanism of this symptom is unclear....
Complex regional pain syndrome (CRPS) is often associated with reduced sound tolerance (hyperacusis) on the affected side, but the mechanism of this symptom is unclear. As compensatory increases in central auditory activity after cochlear injury may trigger hyperacusis, hearing and discomfort thresholds to pure tones (250, 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz) were assessed in 34 patients with CRPS and 26 pain-free controls. In addition, in 31 patients and 17 controls, auditory-evoked potentials to click stimuli (0.08 ms duration, 6 Hz, 60 dB above the hearing threshold) were averaged across 2000 trials for each ear. Auditory discomfort thresholds were lower at several pitches on the CRPS-affected than contralateral side and lower at all pitches on the affected side than in controls. However, ipsilateral hyperacusis was not associated with psychophysical or physiological signs of cochlear damage. Instead, neural activity in the ipsilateral brainstem and midbrain was greater when repetitive click stimuli were presented on the affected than contralateral side and greater bilaterally than in controls. In addition, click-evoked potentials, reflecting thalamo-cortical signal transfer and early cortical processing, were greater contralaterally in patients than controls. Together, these findings suggest that hyperacusis originates in the ipsilateral brainstem and midbrain rather than the peripheral auditory apparatus of patients with CRPS. Failure of processes that jointly modulate afferent auditory signalling and pain (eg, inhibitory influences stemming from the locus coeruleus) could contribute to ipsilateral hyperacusis in CRPS.
Topics: Humans; Complex Regional Pain Syndromes; Hyperacusis; Auditory Threshold; Acoustic Stimulation
PubMed: 36036917
DOI: 10.1097/j.pain.0000000000002766 -
The Journal of the Acoustical Society... Apr 2023The auditory nerve (AN) compound action potential (CAP) is an important tool for assessing auditory disorders and monitoring the health of the auditory periphery during...
The auditory nerve (AN) compound action potential (CAP) is an important tool for assessing auditory disorders and monitoring the health of the auditory periphery during surgical procedures. The CAP has been mathematically conceptualized as the convolution of a unit response (UR) waveform with the firing rate of a population of AN fibers. Here, an approach for predicting experimentally recorded CAPs in humans is proposed, which involves the use of human-based computational models to simulate AN activity. CAPs elicited by clicks, chirps, and amplitude-modulated carriers were simulated and compared with empirically recorded CAPs from human subjects. In addition, narrowband CAPs derived from noise-masked clicks and tone bursts were simulated. Many morphological, temporal, and spectral aspects of human CAPs were captured by the simulations for all stimuli tested. These findings support the use of model simulations of the human CAP to refine existing human-based models of the auditory periphery, aid in the design and analysis of auditory experiments, and predict the effects of hearing loss, synaptopathy, and other auditory disorders on the human CAP.
Topics: Humans; Action Potentials; Acoustic Stimulation; Noise; Hearing Loss; Computer Simulation; Cochlear Nerve; Auditory Threshold; Cochlea
PubMed: 37092943
DOI: 10.1121/10.0017863