Hz Tone Research Articles

Comparison of Chirp Versus Tone Burst- and Click-Evoked Masseteric Vestibular Evoked Myogenic Potentials in Normal-Hearing Adults.

This study aimed at comparing narrowband Claus Elberling level-specific chirp (NB CE-Chirp)-, click-, and tone burst-evoked masseteric vestibular evoked myogenic potentials (mVEMPs). Within-group study design and purposive sampling were performed. A total of 25 normal-hearing individuals participated in the study. The zygomatic electrode montage was used to elicit ipsilateral mVEMP responses using a 500-Hz NB CE-Chirp, a click of 100-μs duration, and a 500-Hz tone burst stimulus. Each of the responses was analyzed based on the absolute peak latency of P11 and N21, the electromyography-scaled peak-to-peak amplitude of the P11-N21 complex, and the interaural asymmetry ratio. A total of 50 ears were tested and had 100% mVEMP responses. The latencies of click-evoked and 500-Hz NB CE-Chirp-evoked mVEMPs were significantly shorter than those of 500-Hz tone burst-evoked mVEMPs (p < .05) for both ears. It revealed a significantly superior P11-N21 amplitude of the 500-Hz NB CE-Chirp and tone burst than clicks for both ears. Intraclass correlation coefficient revealed moderate to excellent test-retest reliability for mVEMP parameters across three different stimulations. The present study supports 500 Hz NB CE-Chirps as effective and reliable stimuli as tone bursts in eliciting mVEMP responses.

Utility of Inter-Frequency Amplitude Ratio of Vestibular-Evoked Myogenic Potentials in Identifying Meniere's Disease: A Systematic Review and Meta-Analysis.

A recently devised parameter of vestibular-evoked myogenic potential (VEMP) based on the principles of frequency tuning is the inter-frequency amplitude ratio (IFAR). It refers to the ratio of the amplitude of 1000 Hz tone burst evoked VEMP to 500 Hz evoked tone burst. A pathology like Meniere's disease changes the frequency response and alters the frequency tuning of the otolith organs. Because IFAR is based on the principle of frequency tuning of VEMP, it is likely to help identify Meniere's disease. Few studies in the last decade have investigated the utility of IFAR in identifying Meniere's disease. However, a systematic review and a meta-analysis on IFAR in Meniere's disease are lacking. The present study investigates whether the IFAR of VEMP helps identify Meniere's disease and differentiates it from healthy ears and other vestibular pathologies. The present study is a systematic review and a meta-analysis. The studies investigating the IFAR of cervical and ocular VEMPs in Meniere's disease, healthy controls, and other vestibular pathologies were searched across research databases such as PubMed, Science Direct, and Scopus. The search strategy was developed using the PICO (population, intervention, comparison, and outcomes) format, and Medical Subject Headings (MeSH) terms and Boolean operators were employed. The systematic review was performed using the Rayyan software, whereas the Review Manager software was used to carry out the meta-analysis. A total of 16,605 articles were retrieved from the databases. After the duplicate removal, 2472 articles remained. These were eliminated using title screening, abstract screening, and full-length inspections. A total of nine articles were found eligible for quality assessment and meta-analysis, and the New Castle-Ottawa Scale was used for quality assessment. After the data extraction, 24 six articles were found to have the desired data format for the meta-analysis. The results showed significantly higher IFAR in the affected ears of individuals in the Meniere's disease group than in the control group's unaffected ears. There was no significant difference between the unaffected ears of individuals in the Meniere's disease group and the ears of the control group. The only study on Meniere's disease and benign paroxysmal positional vertigo found significantly larger ocular VEMP IFAR in ears with Meniere's disease than in benign paroxysmal positional vertigo. This systematic review and meta-analysis found IFAR efficient in differentiating Meniere's disease from healthy controls. We also found an enhanced IFAR as a potential marker for Meniere's disease. However, more investigations are needed to confirm the utility of an enhanced IFAR value in the exclusive identification of Meniere's disease.

Learning to detect auditory signals in noise: Active top-down selection and stable change in signal representations.

Training can improve detection of auditory signals in noise. This learning could potentially occur through active top-down selection mechanisms or stable changes in signal representations. Here, participants were trained and tested (pretest vs. posttest design) on abilities to detect pure tone signals in noise. Auditory evoked potentials (AEPs) to tones were gathered under dichotic listening conditions where participants attended to nontonal stimuli in the opposite ear. Improvements in detection sensitivity were observable regardless of tested tone frequency. This was true in generalization between 861 Hz and 1058-Hz tones (Experiment 1a), and when testing a frequency range > 1 octave (Experiment 2). Such learning was not apparent without training (Experiment 1b). In contrast to behavior, AEP amplitude increases from pre- to posttest were partially specific to trained tone frequencies, even when selective attention was diverted to the opposite ear of tone presentation. Placed in the context of previous work, results suggest that changes in active top-down selection mechanisms and stable signal representations both play a role in auditory detection learning. The mismatch between AEP and behavioral effects suggests a need to consider how these different learning processes can impact detection performance in the variety of listening scenarios a listener may face. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

A molecular psychophysical approach to identify cues for tone-in-noise detection in simultaneous masking

Experiments involving the detection of a tone presented in noise form the basis of many models of psychophysics that are used to estimate frequency resolution and cochlear compression for listeners with normal and impaired hearing. Despite the wide-spread application of tone-in-noise experiments, the cues used by listeners to detect the tone are a matter of debate. Here we adopt a molecular psychophysics approach – decision variable correlation (DVC) – to evaluate the extent to which trial-by-trial responses are consistent with candidate decision variables, including stimulus energy or the temporal envelope. We measured detection thresholds in normal-hearing adults for a 1000-Hz tone presented in one-third octave noise centered on the tone frequency. The tone and noise were gated simultaneously and thresholds were measured for durations of 10, 20, 50, and 100ms. We limited the reliability of energy-based cues by incorporating a roving-level paradigm. Similarly, the use of short tones (e.g., 10 ms) limited the reliability of envelope-based cues. Our results reveal that listeners adopted a strategy that emphasized energy-based cues for short-duration tones and envelope-based cues for long-duration tones. This finding suggests that models of human psychophysics may benefit from incorporating a decision device that adjusts cue weights based on stimulus duration.

Age effects on frequency amplitude ratio of cVEMP

BackgroundThe vestibular system can perceive sound at high intensity levels. The recording of vestibular evoked myogenic potentials (VEMPs) is one of the clinical techniques that capture the vestibular system when activated by sound. In healthy individuals, it has been demonstrated that VEMP thresholds are lower when using low-frequency stimuli, particularly 500 Hz tone burst. Aging affects frequency tuning, causing shift to higher frequencies.MethodsThis study was cross-sectional, which included 80 normal healthy individuals. Each participant in the study were subjected to cervical vestibular evoked myogenic potential (cVEMP) testing using air and bone conduction as a mode of stimulation. The following cVEMP parameters were assessed: cVEMP inter-frequency peak amplitude ratio (FAR): the ratio of peak-to-peak amplitude between 500 Hz and 1000 Hz in the same ear (1000 Hz/500 Hz FPA). Also, rectified FAR is a method of normalizing the amplitude of the VEMP response to the degree of muscle contraction as determined by EMG.ResultsThere were differences among the 5 age groups that were statistically different regarding FAR and rFAR of cVEMP when using air and bone conduction stimuli.ConclusionIn this study, we provided age norms for frequency amplitude ratio (FAR) (1000/500 Hz) of cVEMP using AC and BC stimuli. Participants above the 50 years age group showed significantly larger FAR and rectified FAR than the younger age groups in both the cVEMP. Air and bone conduction stimuli yielded similar FAR results and can be both used in testing.

Characteristics of ipsilateral, contralateral and bilateral masseter vestibular-evoked myogenic potential in healthy adults.

This study aimed to characterise the ipsilateral, contralateral and bilateral masseter vestibular-evoked myogenic potential using clicks and 500 Hz tone burst stimuli in healthy adults. Masseter vestibular-evoked myogenic potential was recorded from 20 healthy participants aged 19-28 years (11 males and 9 females). Masseter vestibular-evoked myogenic potential was recorded using 500 Hz tone burst and click stimuli in ipsilateral, contralateral and bilateral modes. A statistically significant difference was observed between ipsilateral and contralateral stimulation for p11 latency, n21 latency and p11-n21 amplitude for both click and 500 Hz tone burst stimuli. The amplitude of the p11-n21 complex was higher for ipsilateral, contralateral and bilateral stimulations for 500 Hz tone burst than for click stimulus. This study showed a significant difference for p11-n21 amplitude between click and 500 Hz tone burst evoked masseter vestibular-evoked myogenic potential. In addition, bilateral stimulation elicited a larger response than ipsilateral and contralateral stimulation.

Effect of Real-Ear Adjusted Stimuli on Vestibular Evoked Myogenic Potential Variability in Children and Young Adults.

There is large variability in cervical and ocular vestibular evoked myogenic potential (c- and oVEMP) amplitudes. One potential source of variability is differences in ear canal shape and size. Real ear-to-coupler difference (RECD) values are used to measure the acoustic environment of an individual's ear canal. RECD may be a useful measure to calibrate air conducted VEMP stimuli, which are elicited at high intensities and may put patients at risk of unsafe sound exposure. A recommendation for avoiding unsafe exposure is to use a 125 dB SPL stimulus for individuals with an equivalent ear canal volume (ECV) ≥ 0.9 mL and a 120 dB SPL stimulus for individuals with a smaller ECV. The purpose of this project was to determine if using a stimulus calibrated in the ear using RECD values significantly reduces intra-subject and inter-subject VEMP amplitude variability. We hypothesized that using a RECD-calibrated stimulus would significantly reduce inter-subject amplitude variability but not significantly reduce intra-subject variability. We further hypothesized that an RECD-adjusted VEMP stimulus would better protect against delivering unsafe sound exposure compared to the method of using ECV alone. Eleven children (4 to 9 years), 10 adolescents (10 to 18 years), and 10 young adults (20 to 40 years) with normal hearing, tympanometry, vestibular and neurological function participated. On all subjects, RECD was measured twice per ear to account for test-retest reliability. cVEMP and oVEMP were then recorded bilaterally with a 500 Hz tone burst at a traditional and an adjusted VEMP intensity level. The traditional intensity level was 125 dB SPL for individuals with ≥ 0.9 mL ECV and 120 dB SPL for individuals with ≤ 0.8 mL ECV. The adjusted intensity level was calculated by subtracting the average 500 Hz RECD measured values from the 500 Hz normative RECD value. This value was applied as a correction factor to a 125 dB SPL stimulus. Peak to peak amplitudes were recorded and used to calculate asymmetry ratios. Young children had significantly smaller ECVs compared to adolescents and young adults. Young children had larger RECDs; however, this was not significant in post hoc analyses. The method of calibration had no significant effect on intra-subject variability for cVEMP [ F (1, 27)= 0.996, p = 0.327] or oVEMP [ F (1, 25)= 1.679, p = 0.206]. The method of calibration also had no significant effect on inter-subject amplitude variability for cVEMP [ F (1, 120)= 0.721, p = 0.397] or oVEMP [ F (1, 120)= 0.447, p = 0.505]. Both methods of calibration adequately protected against unsafe exposure levels. However, there were subjects with ECVs ≥ 0.9 mL who approached unsafe exposure levels from the ECV-calibrated stimulus, suggesting there may be rare cases in which a 125 dB SPL stimulus is unsafe, even for patients with larger ECVs. The calibration method made no significant difference in intra- or inter-subject variability, indicating that the acoustic environment of the outer ear is not significantly contributing to VEMP amplitude variability. The RECD-adjusted stimulus is effective in protecting against unsafe exposure levels for two trials of both c- and oVEMPs. There may be instances where more than two trials of each test are required, which increases the effective stimulation level. Clinicians should be cautious when delivering VEMPs and not unnecessarily expose patients to unsafe levels of sound.

Analyses Related to the Hearing

I intend to present a few interesting issues for analysis: We deliver a 20 dB 100 Hz tone for 20 milliseconds. The ear receives it; a low tone has to be enhanced, since such a signal energy is too weak to reach the centre. There are doubts whether here active is only a mechanical amplification through an OHC contraction.

Comparison of Traditional Stimuli versus Novel Stimulus-evoked Masseteric Vestibular-evoked Myogenic Potential in Normal-hearing Adults

Abstract Background: Vestibular-evoked myogenic potentials (VEMPs) are the electromyographic (EMG) responses, widely used to assess the functional integrity of otolith organs, i.e., utricle recorded via ocular VEMPs at the level of inferior oblique muscle and saccule via cervical VEMPs at sternocleidomastoid muscle. In addition, VEMPs can also be recorded from other regions of the body as well that includes triceps muscle, trapezius muscle, gastrocnemius muscle, and masseter muscle. The short-latency inhibitory EMG responses recorded at the level of active masseter muscles with acoustic stimulation of vestibular end organ are referred to as masseteric VEMPs (mVEMPs). Aims and Objectives: The present study aimed at comparing various parameters of mVEMP responses such as latency, amplitude, and asymmetry gain across different stimuli. Materials and Methods: A total of 21 normal-hearing healthy individuals with a mean age of x̄ = 21.14 years and σ =1.7 participated in the study with a pure-tone average of 15 dBHL in air and bone conduction testing and normal immittance results for both ears. Results: Therefore, the median latency values for P11 were obtained as M = 11.84 ms, M = 14.67 ms, and M = 11.33 ms in the right ear and M = 11.83 ms, M = 14.83 ms, and M = 11.33 ms in the left ear for clicks, 500 Hz tone burst, and 500 Hz narrow band level specific (NBLS) chirp, respectively. Similarly, for N21, latency values were M = 20 ms, M = 25.16 ms, and M = 20.16 ms in the right ear and M = 19.67 ms, M = 24.67 ms, and M = 19.33 ms in the left ear for clicks, 500 Hz tone burst, and 500 Hz NBLS chirp, respectively. Conclusion: The study suggested mVEMP response to have significantly early latencies and largest amplitudes for 500 Hz NBLS chirp than clicks and 500 Hz tone burst stimuli. The NBLS chirp is an appropriate substitution for clicks and tone burst in assessing vestibulo-trigeminal pathway.

Classification of Acoustic Hearing Preservation After Cochlear Implantation Using Electrocochleography.

The objective to preserve residual hearing during cochlear implantation has recently led to the use of intracochlear electrocochleography (ECochG) as an intraoperative monitoring tool. Currently, a decrease in the amplitude of the difference between responses to alternating-polarity stimuli (DIF response), predominantly reflecting the hair cell response, is used for providing feedback. Including other ECochG response components, such as phase changes and harmonic distortions, could improve the accuracy of surgical feedback. The objectives of the present study were (1) to compare simultaneously recorded stepwise intracochlear and extracochlear ECochG responses to 500 Hz tone bursts, (2) to explore patterns in features extracted from the intracochlear ECochG recordings relating to hearing preservation or hearing loss, and (3) to design support vector machine (SVM) and random forest (RF) classifiers of acoustic hearing preservation that treat each subject as a sample and use all intracochlear ECochG recordings made during electrode array insertion for classification. Forty subjects undergoing cochlear implant (CI) surgery at the Oslo University Hospital, St. Thomas' Hearing Implant Centre, or the University Hospital of Zurich were prospectively enrolled. In this cohort, DIF response amplitude decreases did not relate to postoperative acoustic hearing preservation. Exploratory analysis of the feature set extracted from the ECochG responses and preoperative audiogram showed that the features were not discriminative between outcome classes. The SVM and RF classifiers that were trained on these features could not distinguish cases with hearing loss and hearing preservation. These findings suggest that hearing loss following CI surgery is not always reflected in intraoperative ECochG recordings.

Rethinking the Audiogram for Hearing Aid Selection

Rethinking the Audiogram for Hearing Aid Selection

OR14-4 Acute sleep disruption does not diminish pulsatile growth hormone secretion in pubertal children

Abstract Context: Growth hormone (GH) plays a critical role in glucose homeostasis and linear growth during childhood. GH secretion is controlled by multiple neurotransmitters and hormones. Sleep is also a powerful stimulus for GH secretion. In children, GH pulses occur after sleep onset in association with slow-wave sleep (SWS), but it is unclear if undisrupted sleep is required for normal GH secretion. Given the rising incidence of pediatric sleep disorders such as obstructive sleep apnea (OSA) that cause sleep fragmentation, it is critical to determine whether sleep fragmentation during childhood may dysregulate the somatotropic axis. Objective To quantify how undisrupted vs fragmented sleep affects GH secretion in children. Methods Pubertal subjects (10 M, 9 F; 9.1-14.4 yrs) were randomized to two overnight polysomnographic studies with frequent blood sampling (q10min) to measure GH: fourteen were healthy subjects studied with or without SWS disruption via auditory stimuli (3 sec, 1500 Hz tones, 40-100 dB followed by 18 sec of a 75 dB noise simulating a knock on the door) and five were subjects with OSA studied with or without prescribed continuous positive airway pressure (CPAP); the latter condition was expected to have sleep fragmentation due to untreated OSA. GH pulses were identified using sparse deconvolution. Studies without auditory stimuli or when using CPAP were combined and analyzed as 'undisrupted sleep'. The relationship between GH pulse rate per hour and sleep stage was evaluated using Poisson generalized estimating equations. Results In SWS disruption studies, an average of 77.51 ± 13.61 (range 23-190) auditory stimuli were delivered, causing a 40.02 ± 7.78% decrease in SWS in favor of lighter sleep stages. In subjects with OSA, CPAP withdrawal caused a slight increase in the apnea hypopnea index (1.08 ± 0.10 vs. 2.20 ± 1.70 events/hour of sleep, p=0.07) with no change in sleep stage durations. During undisrupted sleep, subjects had an average of 0.91 ± 0.067 GH pulses/hour with a mean pulse amplitude of 10.03 ± 1.00 ng/mL and mean basal secretion rate of 0.26 ± 0.10 ng/ml per min. GH pulses occurred more frequently during SWS (2.3 pulses/hour SWS, amplitude 9.92 ± 2.59 ng/mL) than during any other sleep stage (P &amp;lt; 0.001). Neither form of sleep disruption affected the distribution of GH pulses across sleep stages, GH pulse amplitude and frequency, nor basal GH secretion. Conclusion In children, nocturnal GH pulses are temporally associated with SWS. However, neither acute fragmentation of SWS nor nocturnal arousals from OSA altered basal or pulsatile GH secretion, indicating that somatotrophic axis activity is preserved in the face of acute sleep disruption in children. Presentation: Sunday, June 12, 2022 11:45 a.m. - 12:00 p.m.

Tone in Noise Detection in Children with a History of Temporary Conductive Hearing Loss.

Children with a history of temporary conductive hearing loss (CHL) during early development may show long-term impairments in auditory processes that persist after restoration of normal audiometric hearing thresholds. Tones in noise provide a simplified paradigm for studying hearing in noise. Prior research has shown that adults with sensorineural hearing loss may alter their listening strategy to use single-channel energy cues for tone-in-noise (TIN) detection rather than rove-resistant envelope or spectral profile cues. Our objective was to determine the effect of early CHL on TIN detection in healthy children compared to controls. Children ages 4-7years, with and without a history of CHL due to otitis media with effusion (OME) before age 3years, participated in a two-alternative forced choice TIN detection task. Audiometric thresholds were normal at the time of testing. Thresholds for detection of a 1000Hz tone were measured in fixed-level noise and in roving-level noise that made single-channel energy cues unreliable. Participants included 23 controls and 23 with a history of OME-related CHL. TIN thresholds decreased with increasing age across participants. Children in both groups showed similar TIN sensitivity and little or no threshold elevation in the roving-level condition compared to fixed-level tracks, consistent with use of rove-resistant cues. In contrast to older listeners with sensorineural hearing loss, there was no detectable change in TIN sensitivity with roving level for children with a history of OME-related CHL.

Extinction Delay and Reinstated Fear Generalization

Background: After classical conditioning and extinction of fear, presentation of an unconditioned stimulus can produce a re-emergence of the extinguished fear response, a reinstatement effect. Previous research has reported that reinstatement of fear of contextual cues after a post-extinction delay could generalize over time to similar contexts. Objective: Two experiments were designed to investigate reinstated fear to a discrete stimulus with either a post-reinstatement delay (Experiment 1) or a post-extinction delay (Experiment 2). Methods: In Experiment 1 rat subjects were randomly assigned to four groups which received fear conditioning and extinction with a 3000 Hz tone CS. Reinstatement conditioning was then conducted with either the same or different CS, and testing for reinstated fear with the original CS was conducted after either a short or long delay following reinstatement. In Experiment 2 all procedures were the same except the long or short delay employed was between extinction and reinstatement instead of after reinstatement. Results: Reinstated fear increased with time to the same CS, and an increase in generalization of reinstated fear over time was observed with a different reinstatement CS (Experiment 1). When the delay employed was between extinction and reinstatement no increase in fear generalization was observed (Experiment 2). Conclusion: The results indicated support for the notion that reinstated fear to a discrete stimulus may generalize over time, but that generalization only takes place when reinstatement is administered a short interval after extinction. The results have implications for clinical behavior therapy treatments of anxiety disorders.

Effects of Age on Cervical Vestibular Evoked Myogenic Potentials and Ocular Vestibular Evoked Myogenic Potentials Using 750 Hz Tone Burst Stimuli among Healthy Adults.

BackgroundThe vestibular evoked myogenic potentials (VEMPs) response characteristics depend on age, stimulus and individual anatomical differences. Therefore, normative data are required for accurate VEMPs interpretations. This cross-sectional study investigates VEMPs age-related changes among healthy adults using 750 Hz short alternating tone burst (TB) stimuli.MethodsFifty adults aged between 23 years old and 76 years old with a mean of 51.56 (SD = 16.44) years old underwent air-conducted (AC) cervical VEMP (cVEMP) and head taps ocular VEMPs (oVEMPs) testing.ResultsThe cVEMPs and oVEMPs response rates reduced significantly at the age of 50-year-old and above. No significant age trends were observed for both cVEMPs and oVEMPs latencies and asymmetry ratios. However, amplitude reduced with increasing age for both cVEMPs, P < 0.001 and oVEMPs, P = 0.01. No significant differences in cVEMPs and oVEMPs latencies, amplitude or asymmetry ratios were identified between gender.ConclusionTo the best of our knowledge, this is the first published normative data for cVEMPs and oVEMPS in Malaysia and Southeast Asia, obtained among healthy adults aged between 23 years old and 76 years old. Health professionals in the region can use these findings as VEMPs normative references in their clinical settings.

Assessment of outcome measures after audiological computer-based auditory training in cochlear implant children

ObjectiveTo validate the clinical use of acoustic change complex (ACC) as an objective outcome measure of auditory training in Egyptian cochlear implant (CI) children and explore how far electrophysiological measures could be correlated to behavioral measures in assessing training outcome. Also to explore the efficacy of computer-based auditory training programs (CBATP) in the rehabilitation process of CI children. MethodsSixty Arabic speaking children participated in the present study. Forty children using monaural CI device served as study group (20 children in subgroup A and 20 children in subgroup B). Both subgroups received traditional speech therapy sessions, additionally subgroup (A) children received computer-based auditory training program (CBATP) at home for three months. Their age ranged from 8 to 17 years. 20 age and sex-matched normal hearing children served as control group as a standardization for the stimuli used to elicit ACC. The study group children were subjected to detailed history taking, parent reported questionnaire (MAIS, Arabic version), aided sound field evaluation, psychophysical evaluation using auditory fusion test (AFT), speech perception testing according to language age, ACC in response to gaps in 1000 Hz tones and language evaluation. This work-up was repeated after 3&6 months for both study subgroups. ResultsChildren of study subgroup (A) showed improvement of auditory fusion test (AFT) thresholds at 3 & 6 months post-training follow up. As regards acoustic change complex (ACC), it can be detected in 85% of subgroup (A) children, 85% of subgroup (B) children and 100% of control group children. Lower ACC gap detection thresholds were obtained only after 3 months in subgroup (A), while after 6 months in subgroup (B). There were statistically significant differences between initial assessment and 3 & 6 months follow up as regards ACC P1 and N2 latencies and amplitudes in both study subgroups, however in subgroup (A), ACC P1 amplitude at 6 months post-training was significantly larger than values of 3 months follow up. There was highly significant correlation between thresholds of AFT and ACC gap detection threshold. ConclusionsACC can be used as a reliable tool for evaluating auditory training outcome in CI children. ACC gap detection threshold can predict psychophysical temporal resolution after auditory training in difficult to test population. CBATP is an easy and accessible method which may be effective in improving CI outcome.

Inter-trial coherence as a measure of synchrony in cervical vestibular evoked myogenic potentials

BackgroundCervical vestibular evoked myogenic potentials (cVEMPs) are surface-recorded responses that reflect saccular function. Analysis of cVEMPs has focused, nearly exclusively, on time-domain waveform measurements such as amplitude and latency of response peaks, but synchrony-based measures have not been previously reported. New MethodTime-frequency analyses were used to apply an objective response-detection algorithm and to quantify response synchrony. These methods are new to VEMP literature and have been adapted from previous auditory research. Air-conducted cVEMPs were elicited using a 500 Hz tone burst in twenty young, healthy participants. ResultsTime-frequency characteristics of cVEMPs and time-frequency boundaries for response energy were established. An inter-trial coherence analysis approach revealed highly synchronous responses with representative inter-trial coherence values of approximately 0.7. Comparison with existing methodsInter-trial coherence measures were highly correlated with conventional amplitude measures in this group of young, healthy adults (R2 = 0.91 – 0.94), although the frequencies at which these measures had their largest magnitude were unrelated (R2 =.02). Conventional measures of peak-to-peak amplitude and latency were consistent with previous literature. Interaural asymmetry ratios were comparable between amplitude- and synchrony-based measures. ConclusionsSynchrony-based time-frequency analyses were successfully applied to cVEMP data and this type of analysis may be helpful to differentiate synchrony from amplitude in populations with disrupted neural synchrony.

Acoustic change complex using short duration stimuli in normal hearing children: temporal resolution and frequency discrimination

Objective Acoustic Change Complex (ACC) is a cortical auditory evoked potential elicited in response to a change in an ongoing sound. Since it is supposed to reflect auditory discrimination at the cortical level, recording of this potential has recently gained much attention. From a technical standpoint, the stimulus used should be long enough to accommodate the needed change. This research addresses the development and standardization of short duration tonal stimuli which can be implemented in most of the Evoked Potential (EP) equipment used in regular Audiology clinics. Methods Short duration tonal stimuli (500 msec.) were generated and edited using Audacity software. Temporal change was done using gap-in-tones stimuli (6, 10, 30 and 50 msec. in 1000 Hz tone). Frequency change was represented by frequency pairs (2%, 4%, 10% and 25% change from 1000 Hz base frequency). The developed stimuli were then used to generate ACC potential in 41 normal hearing children ranging in age from 2 to 10 years. A comparison was held between ACC response recorded using the different stimuli in reference to percent identifiability, morphology, latency and amplitude measures. Results Gap-in-tones at 10 msec. and 4% frequency change could elicit ACC response in 100% of subjects. ACC had the same morphology of the onset response in the majority of subjects, with longer latency and smaller amplitude. ACC amplitude was consistently affected by magnitude of change. Conclusion ACC was successfully recorded in 100% of normal hearing children using the developed short duration tonal stimuli for temporal change (10 msec.) and frequency change (4%). These stimuli can be uploaded in clinical EP equipment. ACC amplitude could be a better indicator of cortical discrimination compared to latency.

Effect of Electrode Montage on 500-Hz Tone Burst Evoked Masseter Vestibular Evoked Myogenic Potential.

Masseter vestibular evoked myogenic potentials (VEMPs) are short-latency myogenic responses obtained in response to electric or acoustic stimulation. It is a relatively newer test that helps assess the vestibulo-trigeminal pathway, thereby gaining more interest in brainstem pathologies like Parkinsonism, multiple sclerosis, and idiopathic random eye movement disorders. The purpose of the study was to compare the effect of zygomatic versus mandibular reference montage on the latency and amplitude of masseter VEMP (mVEMP) using a 500-Hz tone burst stimulus. Twenty healthy participants in the age range of 18-29 years, with no complaints of vestibular signs and symptoms, were recruited for the study. VEMP was recorded for all the participants using 500-Hz tone burst stimuli in zygomatic electrode montage and mandibular electrode montage. mVEMP was recorded in both ipsilateral and contralateral modes. The Wilcoxon signed-ranks test revealed no significant difference between the zygomatic and mandibular montage for both the latency and amplitude parameters (p > .05). This study revealed no significant difference in p11 and n21 latencies as well as p11-n21 rectified amplitude between zygomatic and mandibular montage using a 500-Hz tone burst stimulus in young adults. Hence, utilizing a 500-Hz tone burst, mVEMP can be recorded in zygomatic and mandibular electrode montage.

Neural Markers of Auditory Response and Habituation in Phelan-McDermid Syndrome.

Phelan-McDermid Syndrome (PMS) is a rare genetic disorder caused by deletion or sequence variation in the SHANK3 gene at terminal chromosome 22 that confers high likelihood of comorbid autism spectrum disorder (ASD). Whereas individuals with idiopathic ASD (iASD) can demonstrate diverse patterns of sensory differences, PMS is mainly characterized by sensory hyporesponsiveness. This study used electrophysiology and a passive auditory habituation paradigm to test for neural markers of hyporesponsiveness. EEG was recorded from 15 individuals with PMS, 15 with iASD, and 16 with neurotypical development (NT) while a series of four consecutive 1,000 Hz tones was repeatedly presented. We found intact N1, P2, and N2 event-related potentials (ERPs) and habituation to simple auditory stimuli, both in individuals with iASD and in those with PMS. Both iASD and PMS groups showed robust responses to the initial tone and decaying responses to each subsequent tone, at levels comparable to the NT control group. However, in PMS greater initial N1 amplitude and habituation were associated with auditory hypersensitivity, and P2 habituation correlated with ASD symptomatology. Additionally, further classification of the PMS cohort into genetic groupings revealed dissociation of initial P2 amplitude and habituation of N1 based on whether the deletions included additional genes beyond solely SHANK3 and those not thought to contribute to phenotype. These results provide preliminary insight into early auditory processing in PMS and suggest that while neural response and habituation is generally preserved in PMS, genotypic and phenotypic characteristics may drive some variability. These initial findings provide early evidence that the robust pattern of behavioral hyporesponsiveness in PMS may be due, at least in audition, to higher order factors.