Interaural Amplitude Ratio Research Articles

Exploring the optimal plateau durations of tone burst to elicit masseteric vestibular evoked myogenic potentials: a within-subjects study

ObjectiveThe purpose of the present study was to explore the effect of plateau duration in eliciting masseter vestibular evoked myogenic potentials (mVEMPs) in healthy individuals with hearing sensitivity ≤ 15dBHL.MethodA within-subjects design was utilized in the study. Therefore, ipsilateral tone burst evoked mVEMPs were obtained from 30 healthy individuals using the zygomatic montage at 500 Hz tone bursts. Self-monitoring biofeedback was given during the procedure to confirm the tension of the masseter muscle. mVEMPs were recorded across three different plateau duration from 0 to 2 ms with rise/fall time of 2 ms at 95dBnHL. Hence the median and interquartile range were calculated for descriptive analysis of the data followed by non-parametric inferential statistics.ResultsTone burst evoked mVEMPs were found to be 100% present across all three plateau durations for both ears at 95 dBnHL. P11 and N21 latencies increased with longer plateau durations in both ears. There were no significant differences in P11-N21 peak-to-peak amplitude or interaural amplitude ratio (IAAR) observed across different plateau durations. IAAR was lowest for a 2 ms plateau duration in the 2–2-2 cycle. No significant variations were found across the three plateau durations.ConclusionSignificant differences in P11 and N21 latencies were observed across the three stimulus cycles, while no significant differences were found for P11N21 amplitude and IAAR. Yet, there was found to have the highest amplitude and lowest IAAR for 2–2-2 cycle than 2–0-2 and 2–1-2, suggesting it to be the optimal stimulus among the three of them.

Cervical vestibular evoked myogenic potentials in healthy children: Normative values for bone and air conduction.

To characterize cervical vestibular evoked myogenic potentials (c-VEMPs) in bone conduction (BC) and air conduction (AC) in healthy children, to compare the responses to adults and to provide normative values according to age and sex. Observational study in a large cohort of healthy children (n = 118) and adults (n = 41). The c-VEMPs were normalized with the individual EMG traces, the amplitude ratios were modeled with the Royston-Wright method. In children, the amplitude ratios of AC and BC c-VEMP were correlated (r = 0.6, p < 0.001) and their medians were not significantly different (p = 0.05). The amplitude ratio was higher in men than in women for AC (p = 0.04) and BC (p = 0.03). Children had significantly higher amplitude ratios than adults for AC (p = 0.01) and BC (p < 0.001). Normative values for children are shown. Amplitude ratio is age-dependent for AC more than for BC. Confidence limits of interaural amplitude ratio asymmetries were less than 32%. Thresholds were not different between AC and BC (88 ± 5 and 86 ± 6 dB nHL, p = 0.99). Mean latencies for AC and BC were for P-wave 13.0 and 13.2 msec and for N-wave 19.3 and 19.4 msec. The present study provides age- and sex-specific normative data for c-VEMP for children (6 months to 15 years of age) for AC and BC stimulation. Up to the age of 15 years, c-VEMP responses can be obtained equally well with both stimulation modes. Thus, BC represents a valid alternative for vestibular otolith testing, especially in case of air conduction disorders.

Preliminary observation of galvanic vestibular stimulation-vestibular evoked myogenic potentials in healthy young people

Objective: To introduce the method of galvanic vestibular stimulation-vestibular evoked myogenic potentials (GVS-VEMP) as well as to observe and analyze the parameters and elicited rate of GVS-cVEMP and GVS-oVEMP in healthy young people in China. Methods: Twenty six normal young subjects were recruited for conventional examinations of GVS-VEMP. The subjects were 21-37 years old, average age was (25.8±3.7) years old, including 13 males and 13 females. The galvanic stimulation intensity of 3 mA/1 ms was used to evoke cVEMP and oVEMP on the sternocleidomastoid and inferior extraocular muscles respectively, and the intensity of stimulus was decreased until the response disappeared, the threshold, latency, amplitude, interval phase and interaural amplitude ratio(IAR) were calculated. SPSS18.0 software was used for statistical analysis. Results: All subjects were elicited normal GVS-cVEMP and GVS-oVEMP under 3 mA/1 ms, the elicited rate was 100%. The threshold of GVS-cVEMP was (1.18±0.47) mA, p1 latency was (10.43±1.54) ms, n1 latency was (17.91±1.20) ms, the amplitude was (102.47±56.77) uV and IAR was (0.26±0.20). The threshold of GVS-oVEMP was (1.12±0.50) mA, n1 latency was (8.46±1.05) ms, p1 latency was (11.83±1.27) ms, the amplitude was (9.12±6.82) uV and IAR was (0.25±0.20). In terms of gender and lateral comparison, only the GVS-oVEMP amplitude was higher for male than for female, which had significant statistical difference (P<0.05), and there was no statistical difference in the other parameters between GVS-cVEMP and GVS-oVEMP. Conclusion: GVS-cVEMP and GVS-oVEMP could be elicited in healthy youth population, and the parameters could provide reference for subsequent vestibular function evaluation.

Can a finding of cervical vestibular evoked myogenic potentials contribute to vestibular migraine diagnostics?

To investigate differences in vestibular evoked myogenic potentials (VEMP) results with patients suffering from vestibular migraine and healthy people, taking into consideration values of threshold and latency of occurrence of the characteristic wave complex, size of amplitude, and interaural amplitude ratio. According to the results, determine the importance and usefulness of VEMP in vestibular migraine diagnostics. A total number of 62 subjects were included in the study, 32 of them belonging to a group of patients suffering from vestibular migraine (VM), while other 30 were in a control group of healthy subjects. Information was collected during the diagnostic evaluation. General and otoneurological history of patients and bedside tests, audiological results, videonystagmography and cervical vestibular evoked myogenic potentials (cVEMP) were made. There was a difference in an interaural ratio of amplitudes in the experimental and control groups, but it was not found to be clinically significant. By ToneBurst 500 Hz method, the interaural amplitude ratio higher than 35% was measured in 46.97% subjects, while the response was totally unilaterally missing in 28.8% patients. Even the sophisticated method as cVEMP does not give the ultimate result confirming the vestibular migraine diagnosis, and neither do other diagnostic methods. cVEMP result can contribute to the completion of full mosaic of vestibular migraine diagnostics.

Efficacy of ocular vestibular-evoked myogenic potential in identifying posterior semicircular canal benign paroxysmal positional vertigo.

Benign paroxysmal positional vertigo (BPPV) is a unilateral peripheral vestibular pathology, mostly involving the semicircular canals and the otolith organs. Although equivocal findings exist on the utility of cervical vestibular-evoked myogenic potential in identifying BPPV-associated changes in saccule, ocular vestibular-evoked myogenic potential (oVEMP), which is primarily a utricular response, has sparingly been explored in this population. Hence, the present study aimed at examining oVEMP in individuals with BPPV and comparing them with healthy individuals to illustrate its efficacy in identifying BPPV-associated changes in the utricle. Using a case-control design, oVEMPs were elicited by 500 Hz tone bursts at 125 dB peak sound pressure level and recorded bilaterally from 30 individuals with unilateral posterior canal BPPV and 30 age- and gender-matched healthy controls. There were no inter- or intragroup differences in latency aspects (p > 0.05); however, amplitudes were significantly smaller in BPPV ears compared with the non-BPPV ears of individuals with BPPV as well as ears of healthy controls (p < 0.05). Exceptions to this were five participants with BPPV in whom the affected ears demonstrated larger response amplitude (augmentation) than the unaffected ears. Furthermore, there was significantly larger interaural amplitude ratio in individuals with BPPV compared with the healthy controls (p < 0.05). Interaural amplitude ratio produced the largest effect size among the oVEMP parameters for differentiating BPPV from healthy controls. Large asymmetry ratio of oVEMP, usually exceeding 26.8%, is the most potent characteristic of oVEMP in BPPV. Abnormal oVEMP results confirm utricular pathology in ears with BPPV, and therefore, oVEMP can be used as an objective tool with asymmetry ratio as the parameter of choice for the evaluation of utricular function in persons with posterior canal BPPV.

Characterizing the Effects of Frequency on Parameters of Short Tone-bursts Induced Ocular Vestibular Evoked Myogenic Potentials

Stimulus is the essence of any audiovestibular investigation and ocular vestibular-evoked myogenic potential (oVEMP) would be no different. Several investigations have examined the effect of frequency of stimulus on oVEMP parameters with prime reports concentrated around amplitude and to a lesser extent threshold. Effects of stimulus frequency on latency-related parameters have been sparingly explored with equivocal results. Thus, the aim of this study was to investigate the effects of air-conducted frequency-specific short tone-bursts on latency, amplitude, and threshold-related parameters of various peaks of oVEMP. A normative study was conducted to obtain oVEMP responses from 50 healthy individuals in the age range of 18 - 30 years. Tone-bursts at octave and midoctave frequencies from 250 to 2000 Hz were used to acquire responses from the inferior oblique muscle using contralateral electrode placement. oVEMPs were present in 100% of the individuals at or below the frequency of 1000 Hz. The largest amplitudes and the lowest threshold corresponded to 500 Hz tone-burst, whereas 250 Hz produced largest absolute latencies as well as interpeak latency intervals (P < 0.05). Frequency had no effect on interaural latency difference as well as interaural amplitude ratio. Owing to largest amplitudes and best thresholds, 500 Hz appears better stimuli for clinical recording of oVEMPs. This is true irrespective of the peak complex being assessed is n1p1 or p1n2.

In Vivo Visualized Endolymphatic Hydrops and Inner Ear Functions in Patients With Electrocochleographically Confirmed Ménière’s Disease

To study the correlation between the degree of endolymphatic hydrops as detected in vivo by magnetic resonance (MR) imaging and the auditory and vestibular function in patients with definite Ménière's disease. Prospective observational study. Tertiary referral center for balance disorders. In this prospective study, 41 patients who fulfilled the criteria for definite unilateral Ménière's disease according to the American Association of Otolaryngology-Head and Neck Surgery and who showed a summating potential-to-action potential ratio of greater than 0.4 on electrocochleography were included. Intratympanic contrast-enhanced 3 Tesla MR imaging of the inner ear was performed using a 3D Inversion Recovery Turbo Spin Echo sequence. The degree of endolymphatic hydrops was graded on a Likert scale (0-3) in the cochlea and by vestibular endolymph space ratio in the vestibulum. The degree of hydrops was then analyzed with respect to its correlation with audiometric hearing levels, interaural amplitude ratios of vestibular evoked myogenic potentials, degree of horizontal semicircular canal paresis on caloric irrigation, and disease duration. The degree of hearing loss and the disease duration correlated significantly with cochlear hydrops (r = 0.85; r = 0.34). Sacculus dysfunction was significantly correlated with vestibular hydrops (r = -0.47). There was no significant correlation between horizontal semicircular canal paresis and vestibular hydrops. In patients with clinically and electrocochleographically confirmed definite Ménière's disease, the degree of MR morphological hydrops severity correlates significantly with impairment of hearing function and sacculus function.

Visualization of Endolyphatic Hydrops in Patients with Ménière’s Disease by Locally Enhanced Inner Ear MRI: Correlation with Audiovestibular Function

Objective: The pathophysiologic role of endolymphatic hydrops in Ménière’s disease is still unresolved. The aim of this study was to determine whether the degree of endolymphatic hydrops as it is detected in vivo in patients with definite Ménière’s disease correlates with audiovestibular function. Method: In this prospective study, 37 patients with definite Ménière’s disease were examined with intratympanic contrast enhanced temporal bone MRI. The degree of hydrops was then compared with hearing levels, SP/AP ratios, interaural amplitude ratios of vestibular evoked myogenic potentials and horizontal semicircular canal paresis. Results: There was a significant correlation between the degree of hydrops on the one hand and the averaged hearing level at 0.25 to 1 kHz and 0.5 to 3 kHz (r = 0.71, P &lt; .01) and the vestibular evoked myogenic potential interaural amplitude ratio (r = -0.44, P &lt; .05) on the other hand. A trend toward a correlation was found between the hydrops and the caloric response; no correlation was found between the hydrops and the SP/AP ratio. Conclusion: The degree of endolymphatic hydrops correlates with a progressive loss of auditory and sacculus function in patients with Ménière’s disease.

In vivo visualization of endolyphatic hydrops in patients with Meniere’s disease: correlation with audiovestibular function

Our objective is to determine whether the degree of endolymphatic hydrops as it is detected in vivo in patients with definite Meniere's disease correlates with audiovestibular function. In this prospective study, 37 patients with definite Meniere's disease according to AAO-HNS criteria were included. Intratympanic contrast enhanced temporal bone MRI was performed using a 3D FLAIR protocol. The degree of endolymphatic hydrops in the cochlea and the vestibulum was graded on a Likert scale (0-3). The degree of hydrops was then analyzed with respect to its correlation with audiometric hearing levels, electrocochleographic SP/AP ratios, interaural amplitude ratios of vestibular evoked myogenic potentials and degree of horizontal semicircular canal paresis on caloric irrigation. There was a significant correlation between the degree of hydrops on the one hand and the averaged hearing level at 0.25-1 and 0.5-3kHz and the vestibular evoked myogenic potential interaural amplitude ratio on the other hand. A trend toward a correlation was noticed between the hydrops and the caloric response, no correlation was noticed between the hydrops and the SP/AP ratio. The degree of endolymphatic hydrops correlates with a progressive loss of auditory and sacculus function in patients with Meniere`s disease.

The extent to which a position-based explanation accounts for binaural release from informational masking

Detection was measured for a 500 Hz tone masked by noise (an "energetic" masker) or sets of ten randomly drawn tones (an "informational" masker). Presenting the maskers diotically and the target tone with a variety of interaural differences (interaural amplitude ratios and/or interaural time delays) resulted in reduced detection thresholds relative to when the target was presented diotically ("binaural release from masking"). Thresholds observed when time and amplitude differences applied to the target were "reinforcing" (favored the same ear, resulting in a lateralized position for the target) were not significantly different from thresholds obtained when differences were "opposing" (favored opposite ears, resulting in a centered position for the target). This irrelevance of differences in the perceived location of the target is a classic result for energetic maskers but had not previously been shown for informational maskers. However, this parallellism between the patterns of binaural release for energetic and informational maskers was not accompanied by high correlations between the patterns for individual listeners, supporting the idea that the mechanisms for binaural release from energetic and informational masking are fundamentally different.

The effect of noise on time-intensity trading in lateralization

A two-interval forced-choice lateralization task was used to determine interaural delays and interaural amplitude ratios which, when opposed in quiet, led to chance lateralization; the opposed cues formed time-intensity trades. Three types of signal were used: (1) 20-μs clicks; (2) 250-ms bursts of a 305 Hz tone; and (3) 250-ms bursts of 3965 Hz carrier amplitude modulated to a depth of 100% at a modulation rate of 305 Hz. The addition of various levels of broad-band white noise did not influence the relative effectiveness of the two lateralization cues with pure tone signals; however, the addition of noise to clicks and to AM waveforms led to lateralization judgements in which the cue based on interaural delay appeared to be less effective than in quiet.

Binaural interaction of impaired listeners. A review of past research.

This paper reviews past studies of binaural interaction in impaired listeners. The topics covered include localization and lateralization; equal loudness, centering and lateralization adaptation; detection of signals in noise; and discrimination of interaural time delay and interaural amplitude ratio. Comments concerning experimental design and procedures, as well as interpretation of results, are often included with descriptions of the studies.

The effect of noise on time/intensity trading in lateralization

A standard two‐interval forced‐choice lateralization task was used to determine interaural delays and interaural amplitude ratios which, when opposed in quiet, led to chance lateralization, i.e., the opposed cues formed time/intensity trades. The signals were 20‐μs clicks or 250‐ms bursts of: (1) a 304‐Hz tone, and (2) a 3952‐Hz carrier amplitude modulated to a depth of 100% at a modulation rate of 304 Hz. The addition of various levels of broadband white noise did not influence the relative effectiveness of the two lateralization cues with pure tone signals; however, the addition of noise to clicks and to AM waveforms led to lateralization judgments in which the cue based on interaural delay was less effective than it had been in quiet. This effect can be explained by changes in the frequency region used by Observers listening to clicks but not to AM waveforms. [This research was supported by both Science and the Medical Research Council.]

Sound localization with impaired hearing

Discrimination tests were made on persons with hearing impairments and on patients with multiple sclerosis. Results include estimates of horizontal minimum audible angle (MAA) at eight azimuths, vertical MAA straight ahead, and just‐noticeable differences in interaural time delay (time JND) and interaural amplitude ratio (amplitude JND). The standard stimulus was broadband (0.25–10 kHz), pulsed (1 s) noise. Conductive cases (>35‐dB loss) gave abnormal values in almost all tests. Symmetric sensori‐neural cases with speech discrimination scores above 90% gave roughly normal values in all tests, while the corresponding group with scores below 80% gave elevated values for the vertical MAA and the horizontal MAA on the sides. Meniere's cases had normal MAAs and time JNDs and an amplitude JND that was normal only at high levels. Neurinoma cases gave abnormal values in at least one measurement each, with large intersubject variability. Persons with only one functional ear showed no ability to discriminate intera...

Theory of binaural interaction based on auditory-nerve data. III. Joint dependence on interaural time and amplitude differences in discrimination and detection.

This paper is primarily concerned with issues of symmetry-asymmetry in the joint dependence of binaural performance on interaural time delay and interaural amplitude ratio. The predictions of our model based on auditory-nerve data are shown to be inadequate for available data showing asymmetries in interaural time discrimination. Measured detection thresholds for a 500-Hz tone burst masked by wide-band noise are reported for nonunity amplitude ratios and both polarities of delays in order to test for asymmetries analogous to those observed in the time discrimination case. The detection results show only small asymmetries and are not inconsistent with the model. A general discussion of our model and the implications of available empirical results leads to a suggested modification of the model. We show by an example that modifications of the type we are suggesting are capable of describing the detection data and at least the gross trends of the discrimination data.

Lateral position and interaural discrimination.

Experimental results are described for the dependence on interaural stimulus parameters of subjective lateral-position matches and just-noticeable differences (jnd’s) in interaural amplitude and time. All experiments employed 500-Hz tones presented through acoustically monitored headphones. The overall amplitudes of the stimuli were iteratively adjusted to eliminate subjective loudness cues in the interaural-amplitude jnd experiments. Performance in the experiments is analyzed within the framework of a probabilistic lateralization model in which internal noise is explicitly treated. The model predicts a specific relation between position matches and the interaural amplitude and time jnd’s. The data are qualitatively consistent with the predictions, and the quantitative agreement is good for one subject, moderate for the second, and poor for the third. In particular, the model predicts the observed asymmetry in the dependence of the interaural-time jnd on interaural time delay for nonunity interaural amplitude ratios. Calculated values of the internal noise of the subjective image position are in qualitative agreement with reports by observers of image diffuseness as a function of interaural parameters of the stimulus.

Interaural time discrimination of clicks: Dependence on interaural time and intensity differences

The dependence of the just-noticeable difference (jnd) in interaural time delay on interaural amplitude difference and interaural time delay was measured for a 100-μsec click stimulus using a symmetric, two-interval, two-alternative-forced-choice plus feedback paradigm. Results are similar to those obtained for 500-Hz tone bursts [R. H. Domnitz, J. Acoust. Soc. Am. 53, 1549–1552 (1973)]. As in the tonal data, the most interesting aspect of the data is the asymmetric (about 0 μsec) dependence on interaural time delay when the interaural amplitude ratio is large. The jnd was measured for amplitude ratios of 0. 6. 12. and 20 dB. Results for amplitude ratios less than 20 dB are very consistent, whereas results for 20 dB are more variable. [Work supported by NIH.]

Measurement of the interaural amplitude threshold for a 500-Hz tone

In order to preclude changes in monaural loudness from serving as a cue in the discrimination of interaural amplitude, the amplitude of binaurally presented tone bursts was varied randomly across observation intervals. Subjects were required to discriminate a change in interaural amplitude and to disregard the overall level of the tones. In contrast to previous data reported by Hershkowitz and Durlach [J. Acoust. Soc. Am. 46, 1464–1467 (1969)] for a constant-amplitude condition, interaural amplitude sensitivity decreased markedly as the interaural amplitude ratio decreased from unity. That observers can still detect an interaural amplitude difference of 4.0 dB with interaural amplitude ratios of 30 dB implies that binaural mechanisms, not monaural alone, must be postulated to explain this performance. In a second study, the effects of masking noise on interaural amplitude discrimination were investigated. Whereas the addition of noise to one ear did not increase the interaural phase threshold, the interaural amplitude threshold deteriorated rapidly upon addition of a monaural noise. The addition of a binaural in-phase noise to the signal, producing a correlated noise condition, markedly improved interaural amplitude sensitivity relative to the monaural masker condition.

Symmetry properties of binaural masked detection thresholds with respect to the dependence on interaural time delay and interaural amplitude ratio of the masker

Thresholds for a 500-Hz tone masked by broad-band random noise were measured for conditions that simultaneously include differences in the interaural amplitude ratio and in the interaural time delay of the masking noise. The interaural amplitude ratio of the target was always equal to the interaural amplitude ratio of the masker, and the interaural phase of the target always differed by 180° from the interaural phase of the masker. Measurements include interaural time delays of both polarities for each of five amplitude ratios between 0 and 40 dB. The time delay values were ±200 μsec, ± 500 μsec, and ± 800 μsec. The thresholds for positive and negative values of delays do not differ more than experimental error for any amplitude ratio. It is argued that this symmetry in detection performance, with respect to the sign of the delay, is unexpected in light of the asymmetry observed in interaural time discrimination results [Domnitz, J. Acoust. Soc. Am. 53, 1549–1552 (1972)] and that the results of these two experiments may have important implications for the interaction of time delay and amplitude ratio in binaural hearing models.

Binaural Detection Models: Varying Signal Parameters, Noise Identical at the Two Ears

A previously published statistical decision model of binaural detection called the correlation model [J. Acoust. Soc. Amer. 50, 1494–1511 (1971)] is evaluated further for data obtained with tonal signals in noise, where noise is identical at the two ears and of constant amplitude while signal parameters are varied. Equations are based on the model's expressions for the conditional density functions. Predictions of BMLDs (binaural masking level differences) for variation of interaural amplitude ratio and phase of signal are evaluated with regard to data of Egan [J. Acoust. Soc. Amer, 38, 1043–1049 (1965)] and Colburn and Durlach [J. Acoust. Soc. Amer. 38, 93–103 (1965)]. Comparisons of the correlation model, the equalization-cancellation model [Durlach, J. Acoust. Soc. Amer. 35, 1206–1213 (1963)], and a lateralization model [Hafter, J. Acoust. Soc. Amer. 50, 1116–1122 (1971)] are discussed. Predictions for sets of psychometric functions resulting from binaural detection under several interaural listening conditions are compared to data and psychometric functions presented in Egan [Perception Psychophys. 6, 209–215 (1969)]. [Supported by NIH and CUNY.]