Interaural Differences Research Articles

Auditory localisation in hearing impaired schoolchildren with and without hearing aids

Auditory localisation is part of central auditory processing. The study examined the impact of hearing aids on the auditory localisation ability of non-linguistic stimuli in hearing impaired schoolchildren. Above threshold acoustic signals were presented to 20 children (7-17 years) in a free field condition with 45 loudspeakers placed on a semicircular array. All participants had a bilaterally symmetric moderate sensorineural hearing loss (WHO grade 2) and used behind the ear style (BTE) hearing aids with conventional earmolds. The children had to indicate the position of the signal by a laser pointer. Both high- and low-frequency noise bursts were employed in the tests to separately address spatial auditory processing based on interaural time differences and interaural intensity differences. The examination was performed with and without BTE hearing aids. There was no significant difference between results in the aided and the unaided condition: neither for the different frequency bands nor for the signal positions. The auditory localisation of the hearing impaired children was reduced by 3°-4° for frontal and 5°-11° for lateral positions compared to normal-hearing children. There was no age-relation. In our experimental setting, BTE hearing aids could not compensate the impaired auditory localisation ability of children with sensorineural hearing loss.

Spatial cues can support auditory figure-ground segregation.

A study by Tóth, Kocsis, Háden, Szerafin, Shinn-Cunningham, and Winkler [Neuroimage 141, 108 - 119 (2016)] reported that spatial cues (such as interaural differences or ITDs) that differentiate the perceived sound source directions of a target tone sequence (figure) from simultaneous distracting tones (background) did not improve the ability of participants to detect the target sequence. The present study aims to investigate more systematically whether spatially separating a complex auditory "figure" from the background auditory stream may enhance the detection of a target in a cluttered auditory scene. Results of the presented experiment suggest that the previous negative results arose because of the specific experimental conditions tested. Here the authors find that ITDs provide a clear benefit for detecting a target tone sequence amid a mixture of other simultaneous tone bursts.

Binaural Recordings in Natural Acoustic Environments: Estimates of Speech-Likeness and Interaural Parameters.

Binaural acoustic recordings were made in multiple natural environments, which were chosen to be similar to those reported to be difficult for listeners with impaired hearing. These environments include natural conversations that take place in the presence of other sound sources as found in restaurants, walking or biking in the city, and so on. Sounds from these environments were recorded binaurally with in-the-ear microphones and were analyzed with respect to speech-likeness measures and interaural difference measures. The speech-likeness measures were based on amplitude–modulation patterns within frequency bands and were estimated for 1-s time-slices. The interaural difference measures included interaural coherence, interaural time difference, and interaural level difference, which were estimated for time-slices of 20-ms duration. These binaural measures were documented for one-fourth-octave frequency bands centered at 500 Hz and for the envelopes of one-fourth-octave bands centered at 2000 Hz. For comparison purposes, the same speech-likeness and interaural difference measures were computed for a set of virtual recordings that mimic typical clinical test configurations. These virtual recordings were created by filtering anechoic waveforms with available head-related transfer functions and combining them to create multiple source combinations. Overall, the speech-likeness results show large variability within and between environments, and they demonstrate the importance of having information from both ears available. Furthermore, the interaural parameter results show that the natural recordings contain a relatively small proportion of time-slices with high coherence compared with the virtual recordings; however, when present, binaural cues might be used for selecting intervals with good speech intelligibility for individual sources.

Binaural Response Properties and Sensitivity to Interaural Difference of Neurons in the Auditory Cortex of the Big Brown Bat, Eptesicus fuscus

This study examines binaural response properties and sensitivity to interaural level difference of single neurons in the primary auditory cortex (AC) of the big brown bat, Eptesicus fuscus under earphone stimulation conditions. Contralateral sound stimulation always evoked response from all 306 AC neurons recorded but ipsilateral sound stimulation either excited, inhibited or did not affect their responses. High best frequency (BF) neurons typically had high minimum threshold (MT) and low BF neurons had low MT. However, both BF and MT did not correlate with their recording depth. The BF of these AC neurons progressively changed from high to low along the anteromedial-posterolateral axis of the AC. Their number of impulses and response latency varied with sound level and inter-aural level differences (ILD). Their number of impulses typically increased either monotonically or non-monotonically to a maximum and the latency shortened to a minimum at a specific sound level. Among 205 AC neurons studied at varied ILD, 178 (87%) and 127 (62%) neurons discharged maximally and responded with the shortest response latency at a specific ILD, respectively. Neurons sequentially isolated within an orthogonal electrode puncture shared similar BF, MT, binaurality and ILD curves. However, the response latency of these AC neurons progressively shortened with recording depth. Species-specific difference among this bat, the mustached bat and the pallid bat is discussed in terms of frequency and binaurality representation in the AC.

Short and long term preservation of hearing thresholds corrected for natural hearing loss in cochlear implant recipients using a straight electrode

Objectives: The aim of this study is to investigate short and long term residual hearing preservation (HP), corrected for the natural progress of hearing loss, in cochlear implant (CI) patients receiving a straight electrode array using a round window (RW) approach.Methods: A retrospective and cross-sectional analysis on patients who received a CI with a straight electrode using a RW approach (n = 60) was performed. Audiometric data were obtained at three time points, preoperatively, at first fitting, and one year or more postoperatively. The HP outcome was calculated according to the HP definition as reported by Skarzynski with a PTA of 250, 500, and 1000 Hz (PTA3) and a PTA of 250, 500, 1000, and 2000 Hz (PTA4).Results: The HP outcome at first fitting and at long term follow up fell into the partial HP category, 63.5% (PTA3) and 40.5% (PTA4), respectively according to the Skarzynski definition. A decline in pure-tone average (PTA) was found in the CI ear and in the contralateral ear over time (p < 0.05). Interaural differences remained relatively stable at all frequencies on the long term, except for the frequency 250 Hz (p < 0.05).Discussion: After the initial loss of residual hearing, the hearing thresholds of the CI ear remain relatively stable at long term follow up when corrected for the natural course of hearing loss, except at 250 Hz.Conclusion: CI candidates should be counseled on the risk of long term deterioration of the residual hearing in both the CI ear and the contralateral ear.

Quantitative criteria for age-related hearing loss using audiometric configuration analysis.

To suggest the most adaptable criteria of age-related hearing loss (ARHL) using prevalence matching with population-based data. We chose 30, 25, 20, and 15 dB as gap ranges of cutoff values of the descending type of hearing loss, between an average of low (500Hz, 1kHz) and high (4kHz, 6kHz) frequencies. Interaural difference was defined as 10 or 15dB. Hearing loss was defined over 25dB. We compared the prevalence results of the cross-matching criteria. We used population-based data from the Korea National Health and Nutrition Examination Survey. We assumed that the prevalence of ARHL ranged from 25 to 35%, and this prevalence will increase gradually with age. Among the eight possible criteria, age ≥ 65years, average of all frequencies > 25dB at the each sides, gap between low- and high frequencies ≥ 20dB, and interaural difference ≤ 10dB were the most suitable criteria to suggest a quantitative definition of ARHL audiometrically. In the current study, we recommend the new, quantitative ARHL criteria. The suggested criteria for ARHL might be easily accessed by other researchers to demonstrate their own hypotheses.

Effect of squeeze air film damping on diffraction grating based bio-inspired MEMS directional microphone

A thin air film between two closely oscillating micro structures plays vital role in modifying the system dynamics. The thin air film brings damping and spring effects. Here, we designed a properly perforated MEMS directional microphone to mitigate the squeeze air film damping effects by taking inspiration from fly Ormia ochracea ear response, where damping helps it to produce distinct interaural differences in response to an external acoustic pressure. The coupled and perforated diaphragms are pivoted to a central hinge, and are designed to fit into a multi-user fabrication process. A nano-scale metrology is incorporated to accurately capture the motion of the diaphragms. The characterization of the directional microphone is performed with electrostatic actuation having the same magnitude and different phase difference replicating the scenario of a directional acoustic signal in real world. The experimental results demonstrate a significant vibration magnitude difference, and show a great potential of the fabricated microphone to enhance the directional cues by mitigating the squeeze air film damping.

The effect of room acoustical parameters on speech reception thresholds and spatial release from masking.

In daily life, speech intelligibility is affected by masking caused by interferers and by reverberation. For a frontal target speaker and two interfering sources symmetrically placed to either side, spatial release from masking (SRM) is observed in comparison to frontal interferers. In this case, the auditory system can make use of temporally fluctuating interaural time/phase and level differences promoting binaural unmasking (BU) and better-ear glimpsing (BEG). Reverberation affects the waveforms of the target and maskers, and the interaural differences, depending on the spatial configuration and on the room acoustical properties. In this study, the effect of room acoustics, temporal structure of the interferers, and target-masker positions on speech reception thresholds and SRM was assessed. The results were compared to an optimal better-ear glimpsing strategy to help disentangle energetic masking including effects of BU and BEG as well as informational masking (IM). In anechoic and moderate reverberant conditions, BU and BEG contributed to SRM of fluctuating speech-like maskers, while BU did not contribute in highly reverberant conditions. In highly reverberant rooms a SRM of up to 3 dB was observed for speech maskers, including effects of release from IM based on binaural cues.

On the externalization of sound sources with headphones without reference to a real source.

Sounds presented over headphones are generally perceived as internalized, i.e., originating from a source inside the head. Prior filtering by binaural room impulse responses (BRIRs) can create externalized sources. Previous studies concluded that these BRIRs need to be listener-specific to produce good externalization; however, listeners were generally facing a loudspeaker and asked to rate externalization relative to that loudspeaker, meaning that the source had to be perceived outside the head and also at the right distance. The present study investigated externalization when there is no visual source to match. Overall, lateral sources were perceived as more externalized than frontal sources. Experiment 1 showed that the perceived externalization obtained with non-individualized BRIRs measured in three different rooms was similar to that obtained with a state-of-the-art simulation using individualized BRIRs. Experiment 2 indicated that when there is no real source spectrum to match, headphone equalization does not improve externalization. Experiment 3 further showed that reverberation improved externalization only when it introduced interaural differences. Correlation analyses finally showed a close correspondence between perceived externalization and binaural cues (especially interaural coherence).

Impoverished auditory cues limit engagement of brain networks controlling spatial selective attention

Spatial selective attention enables listeners to process a signal of interest in natural settings. However, most past studies on auditory spatial attention used impoverished spatial cues: presenting competing sounds to different ears, using only interaural differences in time (ITDs) and/or intensity (IIDs), or using non-individualized head-related transfer functions (HRTFs). Here we tested the hypothesis that impoverished spatial cues impair spatial auditory attention by only weakly engaging relevant cortical networks. Eighteen normal-hearing listeners reported the content of one of two competing syllable streams simulated at roughly +30° and −30° azimuth. The competing streams consisted of syllables from two different-sex talkers. Spatialization was based on natural spatial cues (individualized HRTFs), individualized IIDs, or generic ITDs. We measured behavioral performance as well as electroencephalographic markers of selective attention. Behaviorally, subjects recalled target streams most accurately with natural cues. Neurally, spatial attention significantly modulated early evoked sensory response magnitudes only for natural cues, not in conditions using only ITDs or IIDs. Consistent with this, parietal oscillatory power in the alpha band (8–14 ​Hz; associated with filtering out distracting events from unattended directions) showed significantly less attentional modulation with isolated spatial cues than with natural cues. Our findings support the hypothesis that spatial selective attention networks are only partially engaged by impoverished spatial auditory cues. These results not only suggest that studies using unnatural spatial cues underestimate the neural effects of spatial auditory attention, they also illustrate the importance of preserving natural spatial cues in assistive listening devices to support robust attentional control.

Neural coding and perception of auditory motion direction based on interaural time differences.

While motion is important for parsing a complex auditory scene into perceptual objects, how it is encoded in the auditory system is unclear. Perceptual studies suggest that the ability to identify the direction of motion is limited by the duration of the moving sound, yet we can detect changes in interaural differences at even shorter durations. To understand the source of these distinct temporal limits, we recorded from single units in the inferior colliculus (IC) of unanesthetized rabbits in response to noise stimuli containing a brief segment with linearly time-varying interaural time difference ("ITD sweep") temporally embedded in interaurally uncorrelated noise. We also tested the ability of human listeners to either detect the ITD sweeps or identify the motion direction. Using a point-process model to separate the contributions of stimulus dependence and spiking history to single-neuron responses, we found that the neurons respond primarily by following the instantaneous ITD rather than exhibiting true direction selectivity. Furthermore, using an optimal classifier to decode the single-neuron responses, we found that neural threshold durations of ITD sweeps for both direction identification and detection overlapped with human threshold durations even though the average response of the neurons could track the instantaneous ITD beyond psychophysical limits. Our results suggest that the IC does not explicitly encode motion direction, but internal neural noise may limit the speed at which we can identify the direction of motion.NEW & NOTEWORTHY Recognizing motion and identifying an object's trajectory are important for parsing a complex auditory scene, but how we do so is unclear. We show that neurons in the auditory midbrain do not exhibit direction selectivity as found in the visual system but instead follow the trajectory of the motion in their temporal firing patterns. Our results suggest that the inherent variability in neural firings may limit our ability to identify motion direction at short durations.

Sensorineural hearing loss in chronic otitis media: analysis of an overlooked entity!

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; In developing countries, hearing loss continues to be the major public health problem. Among the various causes of hearing loss, chronic otitis media (COM) is one of the commonest. In COM, the presence of sensorineural hearing loss is well established. Our study intends to determine the prevalence of sensorineural hearing loss in chronic otitis media.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; This was a cross sectional descriptive study of 151 subjects between the age group of 10 and 60 years. Patients having unilateral chronic otitis media of both mucosal and squamosal types were selected. All patients were evaluated clinically and audiologically. The type, duration of disease and type of perforation is correlated with degree of sensorineural hearing loss. Interaural differences in bone conduction thresholds at 500 Hz, 1 kHz, 2 kHz and 4 kHz were also noted. &lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results:&lt;/strong&gt; A statistically significant correlation was noted between type of disease and perforation with hearing loss. A significant interaural difference was noted across the speech frequencies. Sensorineural hearing loss of 19.1% was seen.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; Significant sensorineural hearing loss is seen in chronic otitis media which was greater in squamosal disease. Statistically significant correlation was noted between type of disease and type of perforation with hearing loss.&lt;/p&gt;

Audiological Evaluation of Vestibular Schwannoma Patients with Normal Hearing

Objective: To evaluate the audiological aspects of vestibular schwannoma (VS) patients with normal hearing. Study Design: Retrospective study. Setting: Quaternary referral center for skull base pathologies. Patients: The records on 4,000 patients who had been diagnosed with VS between 1986 and December 2017 were retrospectively reviewed. The patients included in the study were the ones who complied with the strict audiological normality criteria, as follows: a pure tone hearing threshold (at the 6-octave-spaced frequencies from 250 to 8,000 Hz) ≤25 dBHL; a word recognition score >90%; and interaural differences ≤10 dB at each frequency. Interventions: Auditory brainstem response (ABR) testing and radiological imaging. Main Outcome Measures: The incidence of normal objective hearing among VS patients, and the diagnostic utility of the ABR and the effect of tumor size and site on the response. Results: The incidence of normal hearing among VS patients was 4.2%. Tinnitus and vertigo were the most common symptoms across tumor grades; 5.6% of the tumors were large and giant tumors. The ABR yielded a sensitivity of 73.6%, with a false negative rate of 26.3% using a cutoff point of 0.2 ms for interaural latency differences. Conclusions: The diagnosis of VS should not be based on audiometric thresholds alone. Alarming signs of VS should be clear to the physician in order not to miss or delay the diagnosis of the disease. The ABR is useful in the diagnosis of VS, but normal results do not exclude the occurrence of the disease in patients with normal hearing.

Characteristics of Nystagmus during Attack of Vestibular Migraine

Objectives The purpose of this study is to investigate characteristics of nystagmus during attacks of vestibular migraine (VM), and to find a distinct clinical feature compared to other migraine and peripheral vestibular disorders. Methods This study is a retrospective chart review of 82 patients satisfied with VM criteria, which is formulated by the new Bárány Society. Spontaneous and positional nystagmus provoked by various head positions were examined with video-nystagmography in all patients. Bithermal caloric test and cervical vestibular evoked myogenic potential test (cVEMP) were also performed. The direction and peak slow-phase velocity (SPV) of nystagmus, unilateral caloric weakness and interaural difference of cVEMP were analyzed. Control groups were lesion side in acute VN for nystagmus results and healthy side in the patients with benign paroxysmal positional vertigo of posterior semicircular canal for caloric and cVEMP results. Chi-square test and Mann-Whitney U-test were used for statistical analysis. Results During the acute attack, nystagmus was seen in 71.9% (59 of 82) of patients. Horizontal nystagmus was the predominant type. Peak SPV in VM patients was much slower than in the control group (2.37±1.73 °/sec vs. 17.05±12.69 °/sec, p＜0.0001). There was no significant difference on the result of both caloric and cVEMP test, compared to those of control groups. Conclusion Nystagmus with horizontal directions and low SPV was dominant form in the attack of VM. Close observation of nystagmus can be helpful to make a correct diagnosis and to understand the pathomechanism of vertigo in VM. Keywords: Vestibular migraine; Ictal phase; Nystagmus 중심 단어: ì „ì •íŽ¸ë‘í†µ, 발작기, 안진

The Effects of Dynamic-range Automatic Gain Control on Sentence Intelligibility With a Speech Masker in Simulated Cochlear Implant Listening.

"Channel-linked" and "multi-band" front-end automatic gain control (AGC) were examined as alternatives to single-band, channel-unlinked AGC in simulated bilateral cochlear implant (CI) processing. In channel-linked AGC, the same gain control signal was applied to the input signals to both of the two CIs ("channels"). In multi-band AGC, gain control acted independently on each of a number of narrow frequency regions per channel. Speech intelligibility performance was measured with a single target (to the left, at -15 or -30°) and a single, symmetrically-opposed masker (to the right) at a signal-to-noise ratio (SNR) of -2 decibels. Binaural sentence intelligibility was measured as a function of whether channel linking was present and of the number of AGC bands. Analysis of variance was performed to assess condition effects on percent correct across the two spatial arrangements, both at a high and a low AGC threshold. Acoustic analysis was conducted to compare postcompressed better-ear SNR, interaural differences, and monaural within-band envelope levels across processing conditions. Analyses of variance indicated significant main effects of both channel linking and number of bands at low threshold, and of channel linking at high threshold. These improvements were accompanied by several acoustic changes. Linked AGC produced a more favorable better-ear SNR and better preserved broadband interaural level difference statistics, but did not reduce dynamic range as much as unlinked AGC. Multi-band AGC sometimes improved better-ear SNR statistics and always improved broadband interaural level difference statistics whenever the AGC channels were unlinked. Multi-band AGC produced output envelope levels that were higher than single-band AGC. These results favor strategies that incorporate channel-linked AGC and multi-band AGC for bilateral CIs. Linked AGC aids speech intelligibility in spatially separated speech, but reduces the degree to which dynamic range is compressed. Combining multi-band and channel-linked AGC offsets the potential impact of diminished dynamic range with linked AGC without sacrificing the intelligibility gains observed with linked AGC.

Redundant Information Is Sometimes More Beneficial Than Spatial Information to Understand Speech in Noise.

To establish a framework to unambiguously define and relate the different spatial effects in speech understanding: head shadow, redundancy, squelch, spatial release from masking (SRM), and so on. Next, to investigate the contribution of interaural time and level differences to these spatial effects in speech understanding and how this is influenced by the type of masking noise. In our framework, SRM is uniquely characterized as a linear combination of head shadow, binaural redundancy, and binaural squelch. The latter two terms are combined into one binaural term, which we define as binaural contrast: a benefit of interaural differences. In this way, SRM is a simple sum of a monaural and a binaural term. We used the framework to quantify these spatial effects in 10 listeners with normal hearing. The participants performed speech intelligibility tasks in different spatial setups. We used head-related transfer functions to manipulate the presence of interaural time and level differences. We used three spectrally matched masker types: stationary speech-weighted noise, a competing talker, and speech-weighted noise that was modulated with the broadband temporal envelope of the competing talker. We found that (1) binaural contrast was increased by interaural time differences, but reduced by interaural level differences, irrespective of masker type, and (2) large redundancy (the benefit of having identical information in two ears) could reduce binaural contrast and thus also reduce SRM. Our framework yielded new insights in binaural processing in speech intelligibility. First, interaural level differences disturb speech intelligibility in realistic listening conditions. Therefore, to optimize speech intelligibility in hearing aids, it is more beneficial to improve monaural signal-to-noise ratios rather than to preserve interaural level differences. Second, although redundancy is mostly ignored when considering spatial hearing, it might explain reduced SRM in some cases.

The Effect of Nonlinear Amplitude Growth on the Speech Perception Benefits Provided by a Single-Sided Vocoder.

Purpose For listeners with single-sided deafness, a cochlear implant (CI) can improve speech understanding by giving the listener access to the ear with the better target-to-masker ratio (TMR; head shadow) or by providing interaural difference cues to facilitate the perceptual separation of concurrent talkers (squelch). CI simulations presented to listeners with normal hearing examined how these benefits could be affected by interaural differences in loudness growth in a speech-on-speech masking task. Method Experiment 1 examined a target-masker spatial configuration where the vocoded ear had a poorer TMR than the nonvocoded ear. Experiment 2 examined the reverse configuration. Generic head-related transfer functions simulated free-field listening. Compression or expansion was applied independently to each vocoder channel (power-law exponents: 0.25, 0.5, 1, 1.5, or 2). Results Compression reduced the benefit provided by the vocoder ear in both experiments. There was some evidence that expansion increased squelch in Experiment 1 but reduced the benefit in Experiment 2 where the vocoder ear provided a combination of head-shadow and squelch benefits. Conclusions The effects of compression and expansion are interpreted in terms of envelope distortion and changes in the vocoded-ear TMR (for head shadow) or changes in perceived target-masker spatial separation (for squelch). The compression parameter is a candidate for clinical optimization to improve single-sided deafness CI outcomes.

Extending signal detection theory approaches up the central pathway: Auditory midbrain models

The application of signal detection theory (SDT) to peripheral encoding of stimulus parameters provided a quantitative basis for understanding auditory-nerve (AN) responses. Siebert’s development of this strategy, based on relatively simple analytical models, laid the groundwork for Heinz’s extension that took advantage of computational AN models. These studies applied the Cramer-Rao lower bound (CRLB) to estimate just-noticeable differences of stimulus parameters, assuming that underlying neural responses could be described as non-homogenous Poisson processes (NHHP) and that the brain acts as an optimal processor. Krips and Furst carried this approach into the central nervous system, first showing that coincidence-detector neurons that receive excitatory and/or inhibitory NHHP inputs produce outputs that are also NHHP. These models were tested using the CRLB for sensitivity to interaural differences in time and level. Here, we carry the approach a step further along the auditory pathway to the auditory m...

Audiologic prognostic factors for hearing preservation following vestibular schwannoma surgery

Postoperative hearing loss after vestibular schwannoma (VS) removal still remains a lifelong problem for the patients. The present study analyzes the problem of hearing preservation after VS removal from a different angle than available professional literature on this topic. To identify audiologic factors which determine the extent of hearing loss in patients operated on for VS. The study group included 86 patients operated on due to VS accessed via the middle cranial fossa. The analyses involved the effect on absolute hearing loss, which was calculated on the basis of the results of pure-tone audiometry performed preand postoperatively, and factors included in the preoperative audiologic tests, such as pure-tone audiometry, speech audiometry, auditory brainstem response (ABR), and impedance audiometry. The following parameters were demonstrated to have a prognostic value: 1. hearing thresholds at 125 Hz, 500 Hz and 1,000 Hz for the operated ear, Pure Tone Average (PTA) - calculated specifically at 500 Hz, 1,000 Hz and 2,000 Hz and at 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz for the operated ear, and normal audiometric curve; 2. speech discrimination ranging from 55 dB to 75 dB for the operated ear, speech detection threshold (SDT) in the operated ear and interaural difference at 25-35 dB (non-operated vs operated ear); 3. presence of wave V, the values of I-V and III-V intervals for the operated ear, the amplitude of wave V, and the interaural ratio of wave V amplitudes; 4. intensity level for obtaining stapedial reflex or an abnormal reflex at Ipsi 500 Hz, 1,000 Hz and 2,000 Hz, and Contra 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz. The better the preoperative hearing status, the more substantial surgery-related hearing loss was observed. A number of preoperative parameters of the basic diagnostic set of audiologic tests present a prognostic value for the degree of surgery-related hearing loss in VS patients.

Assessment of the utricular function in posterior canal benign paroxysmal positional vertigo patients before and after canalith repositioning maneuvre and its relation to residual dizziness

Background: In benign paroxysmal positional vertigo (BPPV), the otoconia are dislodged from their usual position within the utricle and migrated into one of the semicircular canals. Utricular dysfunction in BPPV has been reported. Residual dizziness (RD) is common after the treatment.Objective: To assess the utricular function in patients with posterior canal BPPV after canalith repositioning maneuver (CRM) using ocular vestibular evoked myogenic potential (oVEMP) and to correlate the findings with any RD after CRM.Methods: Thirty adult patients with posterior canal BPPV (6 males and 24 females) were compared to well-matched controls. The oVEMP and Dizziness Handicap Inventory (DHI) Questionnaire were administrated before and after successful CRM.Results: Before CRM, the affected ear showed a significant delay in latency of N1 in the affected ear oVEMP and a significantly decreased in N1–P1 amplitude compared to controls and to the non-affected ears. After CRM their amplitudes were comparable. The BPPV group had a greater interaural amplitude difference percent (IAAD%) compared to controls before and after CRM. The non-affected ear showed only decrease in N1–P1 amplitude compared to controls. After CRM the affected ear amplitude increased and became comparable to the controls. The IAAD% was larger in RD group than non-RD group before and after CRM. The dizziness handicap severity decreased after CRM. But the occurrence of RD could not be predicted from DHI scores.Conclusion: Utricular function measured by oVEMP in the affected ear improved after CRM, and contralateral ear showed sub-clinical affection. Persistent VEMP abnormality reflecting persistent utricular dysfunction was related to residual dizziness.