Significant Differences In Wave Research Articles

Assessment of cochlear electrophysiology in typically developing children and children with auditory processing disorder

ObjectiveChildren with auditory processing disorder (APD) are reported to have abnormal auditory brainstem responses (ABR) but little is understood about their cochlear integrity. Poor cochlear integrity can affect neural responses. In this study, cochlear and auditory brainstem integrity was investigated in children with APD. MethodTwenty children with APD, sixteen typically developing children and twenty adults participated in this study. Click evoked electrocochleography (ECochG) and ABRs were recorded from all the participants. Cochlear responses were analyzed using a) latency and amplitude of summating potential; action potential, b) transmission time between summating potential and action potential, c) summating potential/action potential amplitude ratio and d) action potential latency difference to condensation and rarefaction polarity. Amplitude in the ABR components was examined. ResultsChildren with APD showed similar cochlear function to the typically developing children. There were no significant differences in wave I amplitude between children with APD and typically developing children. However, wave V amplitude was significantly reduced in children with APD compared to typically developing children. ConclusionIn the absence of any functional differences in the cochlea, children with APD can show poor amplitude in the later components of the ABR. The ABR anomalies observed in children with APD arise due to poor neural processing, possibly after the first auditory synapse.

Analytical approach to scattering of SH waves by an arbitrary number of semicircular canyons in an elastic half space

The wave function expansion method is used to propose a semi-analytical solution for the scattering of plane SH waves by a canyon group containing an arbitrary number of semicircular canyons (including an infinite number of periodically distributed ones). The frequency-domain solution is verified by comparing with two past solutions for a single canyon and two canyons, respectively. A systematic parametrical analysis is carried out in the frequency domain with respect to the size, distribution, quantity, and spacing distance of the canyons. It is found that the surface displacement amplitudes of the canyon group are intensified and reduced relative to those of a single canyon for vertical and grazing incidences of SH waves, respectively. Time-domain results are obtained by the inverse FFT after verification by a hybrid time-domain finite element-boundary element approach. Significant differences in wave propagating and scattering are illustrated between a canyon group and a single canyon. The canyon group can amplify the vertically incident waves by focusing and reduce the grazing incident waves by continuous shielding.

Effect of delivery mode on neonate auditory brainstem responses to air- and bone-conducted stimuli

ObjectivesThe object of this study was to examine if caesarean section delivered neonates have different middle ear function relative to neonates with vaginal delivery. MethodsAuditory brainstem responses (ABRs) were examined in caesarean section delivered (n = 23) and vaginally delivered (n = 29) neonates. ABRs were also evoked with air- and bone-conducted stimuli (i.e., clicks and CE-Chirps) and presented at a screening intensity level (i.e., 30 dB nHL). Wave V latencies and amplitudes were examined as a function of mode of delivery and stimuli. ResultsStatistically significant longer wave V latencies evoked with air-conducted stimuli were seen in caesarean section delivered neonates (p = .042). There was no statistically significant difference in wave V latencies with bone-conducted stimuli among the two groups of neonates (p = .42). There were no significant differences in wave V amplitude between neonates with caesarean section and vaginal delivery for air-conducted (p = .42) stimuli. Wave V amplitudes were not significantly different as a function of mode of delivery with CE-Chirp stimulus (p = .41). Wave V amplitudes were significantly larger for the caesarean section delivered neonates with the bone-conducted click stimulus (p = .036). ConclusionsThe ABR wave V latency disparity with air- and bone-conducted stimuli support the notion that differences in middle ear function exist between the two groups of newborns. It was speculated that delayed fluid resorption in the middle ear exists in neonates with caesarean section delivery compared to those with vaginal delivery.

Potenciais evocados auditivos de tronco encefálico em fumantes

RESUMO Objetivo: comparar os resultados dos exames de potenciais evocados auditivos de tronco encefálico em indivíduos não tabagistas e tabagistas. Métodos: foram estudados 40 indivíduos, sendo 20 não tabagistas e 20 tabagistas, com idades entre 20 e 59 anos. Todos os participantes incluídos na pesquisa deveriam apresentar respostas de limiares tonais dentro dos padrões da normalidade e timpanometria tipo A com presença de reflexos acústicos contralaterais e ipsilaterais. Em ambos os grupos foram realizados os potenciais evocados auditivos de tronco encefálico (PEATE), por meio de cliques. Os parâmetros que foram utilizados na comparação dos dois grupos foram as latências absolutas das ondas I, III e V; as interlatências das ondas I-III, I-V e III-V em ambas as orelhas; a diferença da latência interpico I-V entre as duas orelhas e a diferença interaural da latência absoluta da onda V entre as duas orelhas. Resultados: os resultados encontrados mostraram que o grupo de tabagistas apresentou latência I da Orelha Direita (p=0,036), latência V da Orelha Direita (p=0,007), latência V da Orelha Esquerda (p=0,014), interlatência III-V da Orelha Direita (p=0,015) e Orelha Esquerda (p=0,016) significantemente maior que o grupo de não tabagistas. Não houve diferença significante na latência da onda V entre as duas orelhas. Conclusão: os resultados da pesquisa levaram à conclusão de que o tabaco é um fator de risco para o sistema nervoso auditivo central, que pode interferir nas latências e interlatências das ondas do PEATE no grupo de tabagistas quando comparado com o grupo de não tabagistas.

Auditory Brainstem Evoked Response: response patterns of full-term and premature infants

Auditory Brainstem Response (ABR) is important for the early diagnosis of hearing impairment in infants.AimTo compare ABR responses in full-term and premature infants; gender and ear were taken into account.MethodsA cross-sectional prospective cohort study was carried out. We evaluated 36 full-term and 30 premature infants that had passed the Transient Otoacoustic Emissions test, had type A tympanometric curves, and had no risk factor for hearing loss besides prematurity. The evaluations were done from the time of hospital discharge to the third month of life, and consisted of a clinical history, acoustic immittance testing and ABR evaluation.ResultsThe comparison of absolute and interpeak wave I, III and V latencies in right and left ears revealed a statistically significant difference at the interpeak I-III. There was no significant gender differences in the comparison of results. Significant difference in wave I, III and V absolute latencies at 80 dB and in wave V at 60 db and 20 db were observed in a comparison of absolute and interpeak latencies between full-term and premature infants. An inverse correlation was found between age and absolute latencies.ConclusionsThe maturity of the auditory system influences ABR responses in infants. To avoid misinterpretation of results, gestational age must be taken into account in the analysis of ABR in pediatric population.

Test-retest reliability of auditory brainstem responses to chirp stimuli in newborns

Objective: The purpose of this study was to examine the test-retest reliability of auditory brainstem responses (ABRs) to air- and bone-conducted chirp stimuli in newborns as a function of intensity. Design: A repeated measures quasi-experimental design was employed. Study sample: Thirty healthy newborns participated. ABRs were evoked using 60, 45, and 30 dB nHL air-conducted CE-Chirps and 45, 30, and 15 dB nHL bone-conducted CE-Chirps at a rate of 57.7/s. Measures were repeated by a second tester. Results: Statistically significant correlations (p <.0001) and predictive linear relations (p <.0001) were found between testers for wave V latencies and amplitudes to air- and bone-conducted CE-Chirps. There were also no statistically significant differences between testers with wave V latencies and amplitudes to air- and bone-conducted CE-Chirps (p >.05). As expected, significant differences in wave V latencies and amplitudes were seen as a function of stimulus intensity for air- and bone-conducted CE-Chirps (p <.0001). Conclusions: These results suggest that ABRs to air- and bone-conducted CE-Chirps can be reliably repeated in newborns with different testers. The CE-Chirp may be valuable for both screening and diagnostic audiologic assessments of newborns.

Sex differences in brain stem auditory evoked potentials and P300 examination in patients with mild cognitive impairment and Alzheimer's disease

To compare the sex differences on brain stem auditory evoked potentials (BAEP) and P300 in the elderly patients with mild cognitive impairment (MCI) and the patients with Alzheimer's disease (AD). Thirty-eight elderly patients with MCI, 26 cases of AD and 20 health controls (HC) were examined with BAEP, P300 . Sex difference of the variables was compared inter-and intra-groups. Significant sex differences of BAEP were found in the latency period wave III, V of left side in the MCI group (P <0.01), in the latency period wave IV, V of left side in HC group (P<0.01), and no such differences were found in AD group. The females had longer latency period in P300 measurement than males in MCI group (P <0.01), but there were no significant differences within AD or HC groups. The males showed significant differences in wave I, II in left side between the MCI and AD groups. The males also showed significant difference in wave I, III approximate, equals V in left side, wave IV in right side between AD and HC groups, and so did the females in wave I approximate, equals V in both sides. The males had significant difference in the left wave III, IV and right wave I, IV, V between MCI and HC groups, and so did the females in right side wave I, II, V. In P300, longer latency waves were found in AD group than in MCI group. Both sexes showed significant differences in the latency of Fz, Cz, Pz between AD and HC groups, but no significant differences were found in the latency of Fz, Cz, Pz in the females between the MCI and HC groups. Sex differences were found in the examination of both BAEP and P300 in MCI group, but not in AD group. The people of same sex have different expression of BAEP and P300 among MCI, AD and HC groups, suggesting the sex difference should be considered in the differential diagnosis.

Improving the Frequency Specificity of the Auditory Brain Stem Response

Several investigators have suggested that the use of tonal stimuli shaped with nonlinear windowing functions can improve the frequency specificity of the auditory brain stem response (ABR). This study investigated the effects of different windowing functions on the ABR for 30 normal-hearing adults and 30 adults with high-frequency hearing loss. These hearing-impaired patients often produce an abnormal click-evoked ABR because of the influence of the high-frequency loss. Each subject was evaluated using a click stimulus and a 500 Hz tone burst gated with one linear and four nonlinear windowing functions. There were no significant differences in wave V latency between the groups for any of the five windowed tone burst conditions. These results suggest that any of the windowing functions used would be effective for 500 Hz tonal ABRs with this population of hearing-impaired adults.

Effects of relative starting phase and frequency separation of two‐tone stimuli on the brain‐stem auditory‐evoked response

Brain-stem auditory-evoked responses (BAERs) were obtained in six normal-hearing adults using single-tone and two-tone stimuli arithmetically centered around 4000 Hz. Two-tone stimuli varied in frequency separation from 200 to 3200 Hz, and started in-phase (homophasic) or 180 deg out-of-phase (antiphasic) with each other. Responses to each of the single-tone components of the two-tone stimuli were elicited and then summed for comparison with responses to the two-tone stimuli. Results indicated no significant difference in wave V latency between homophasic or antiphasic two-tone conditions, and summed single-tone conditions. Under the homophasic condition, the mean latency for the widest frequency separation of the tones was significantly longer than those for narrower separations. A significant difference in wave V amplitude between two-tone phase conditions was found for frequency separations of 200, 400, and 3200 Hz only. Summed single-tone BAERs demonstrated a significantly larger wave V amplitude than responses from either two-tone phase condition at all frequency separations.

Gender, Head Size, and ABRs Examined in Large Clinical Sample

Intergender differences in auditory brain stem response (ABR) latencies have been attributed to intergender differences in head size. We examined ABR data obtained clinically and head dimensions measured from mastoid to mastoid and mastoid to vertex to derive horizontal and vertical vectors which might scale lengths of horizontally and vertically oriented pathways, respectively. Correlations with ABR latencies were all somewhat weak, and slopes of regressions were found to be too small to fully account for intergender latency differences. Head-size matched male and female samples also demonstrated significant differences in wave V latency, and, even in cases with relatively large heads, the use of a head-size correction could not be justified. The coupling between head dimensions and the I-V interpeak interval appears to be small enough to be ignored for clinical purposes. Nevertheless, to the extent to which relationships exist between head dimensions and ABR latency measures, this nonpathologic variable may be completely neutralized through the use of interpeak latency ratios (e.g., wave V latency divided by wave I latency).

Effects of sex on auditory brainstem responses in infancy and early childhood.

The effects of sex on I-III, III-V and I-V interwave intervals and I, III, V ABR waves latency values have been studied in 171 normal children born at term, 94 males and 77 females, aged between 2 and 720 days. The obtained data confirm that latency values decrease progressively with age, and show that there is a statistically significant difference in wave III and V latency values and in III-V and I-V intervals between males and females. Moreover, these differences seem to increase with age. The authors also discuss the possible underlying mechanisms and claim that even in infancy, sex-related variability should be taken into account.

ＡＢＲの相互相関関数による解析

Cross correlation analysis of auditory brain stem response (ABR) by means of the fast Fourier transform (FFT) was performed in normal subjects and its clinical significance was discussed.Cross correlation functions were computed between individual ABRs and each of following three kinds of normative ABR templates (nABR): (1) mean of ABR recordings from 30 normal males (MnABR), (2) mean of recordings from 30 normal females (FnABR) and (3) mean of MnABR and FnABR (MFnABR), because significant difference in wave V latency between MnABR and FnABR was observed. It was, therefore, subsequent that three kinds of cross correlation functions were obtained for each individual ABR. As the cross correlation index, R0 (correlation coefficient at 0msec), RM (maximal correlation coefficient) and DL (latency delay in msec) were adopted.Means and standard deviations of the parameters in normal subjects were compared among three kinds of cross correlation functions. From the results, evaluation of ABR waveform characteristics with cross correlation analysis using nABR of the same gender seems to be more significant than the analysis using MFnABR or using nABR of the other gender.

Bilaterally Recorded Auditory Brainstem Responses to Monaural Stimulation: Latency and Amplitude Differences in Normal Subjects

Ipsilaterally and contralaterally (forehead-mastoid) recorded ABRs to monaurally administered clicks at 90 dB nHL were compared in 16 young normal-hearing female subjects (32 ears). The comparisons were made with regard to latencies and amplitudes of waves I, III and V, and the results concern group statistics. Wave I was recordable in the contralateral derivation in less than 50% of the cases. The amplitudes of waves I and III were significantly smaller, and the latency of wave III significantly shorter (by an average of 0.15 ms) in the contralaterally recorded ABR. There was a tendency for wave V to diminish and to lag in the contralateral recording; however, there were no statistically significant differences in wave V amplitude and latency between the two sides. Nor was there found to be any significant variability differences concerning wave III and wave V latencies between the two derivations. The dominance of the wave V peak-to-peak amplitude was established in both recordings. Two concluding computations showed that there were no differences between right and left ear stimulation, and no differences between recordings performed with the ground electrode applied to the nasion or to the sternum.

Comparison of brain stem auditory evoked potentials for monaural and binaural stimuli

This study examined the relation of brain stem auditory evoked potentials (BAEPs) for monaural and binaural click stimuli. Responses were recorded from normal subjects for 4 stimulus levels of 50, 70, 90 and 110 dB peSPL peak-to-peak, corresponding to monaural sensation levels of 7, 27, 47 and 67 dB SL. Wave amplitude and latency values were analyzed for the effects of the binaural stimulus condition. Responses to binaural stimuli were compared to the summed responses to monaural stimuli to estimate binaural interactions. The results show that responses to a binaural stimulus have significantly greater wave amplitudes than responses to a monaural stimulus. If a response to a binaural stimulus is compared to the sum of the responses to the corresponding monaural stimuli, however, there are no significant differences in wave V amplitudes. Latency values are equal for the two stimulus conditions. Calculation of a continuous wave form representing the difference (point-by-point) between the response to a binaural stimulus and the summed response to the two monaural stimuli shows that significant binaural interactions occur with a latency of 7–10 msec. Additional interactions occur with a latency of 12–16 msec. Although neural and sonomotor sources may contribute to these short latency binaural interactions, acoustic cross-talk appears to account for a significant portion of the observed interaction.