No abstract

In this study, the cross-correlation function was applied in the evaluation of MLR thresholds in the low and middle frequencies. The parameters of the cross-correlation function consist of the correlation coefficient at a lag-time of zero (RO), the maximum correlation coefficient (RM), and the latency delay on the lag-time axis at the point of the maximum correlation coefficient (DL). The normal limits of the parameters of cross-correlation at the MLR threshold level, which was identified by visual detection across frequencies, were obtained in normal-hearing and hearing-impaired subjects. The cross-correlation functions for two traces were also performed below threshold level. All cross-correlation parameters (RO, RM and DL) below threshold level were outside normal limits in 91% of all the subjects. The incidence of the only RM or DL parameter value within normal limits was 6% or 3% of all cases at the subthreshold level. Correlation data allow precise measurements of the MLR threshold and enhance the sensitivity of the definition of the MLR threshold. In addition, our study provides quantifiable information for estimating MLR threshold.

Objective: This study aimed to determine the clinical value of air-and bone-conduction auditory brainstem responses (ABRs) in children with congenital external auditory canal atresia (EACA).Methods: Air-and bone-conduction click-evoked ABRs in 38 children having congenital EACA were compared with 34 children having normal hearing.Results: ABR threshold for air and bone conduction were 66.53 ± 7.12 and 12.55 ± 6.96 dBnHL, respectively, in children with congenital EACA, as well as 25.32 ± 2.66 and 10.71 ± 4.51 dBnHL, respectively, in children with normal hearing. The two groups showed statistical difference in air-conduction ABR thresholds. Meanwhile, air-bone ABR threshold gap was greater in children with EACA than in children with normal hearing, and bone-conduction ABR wave latencies did not statistically differ between the two groups. Conclusion:Bone-conduction ABR is valuable in assessing the function of cochlea, auditory nerve, and brainstem in individuals with congenital EACA. The study has important clinical value in the objective differential diagnosis of conductive deafness with combined application of air-and boneconduction ABRs. Subjects and Methods SubjectsData from 38 infants (50 ears) aged 1-12 months (mean age = 4.6 months) diagnosed with EACA were collected from Children's Hospital of Fudan University between August 2014 to March 2015. The subjects were 28 boys, of which 12 cases were bilateral. Furthermore, the control group consisting of 34 normal infants (68 ears) aged 1-9 months (mean age = 4.1 months) were subjected to otoscopy, tympanometry, otoacoustic emission, and ABR; No hearing losses were reported among the children. For 38 ECAA infants, CT scan and ABR were used to diagnosis and assessment. This work was approved by the Ethics Committee of Children's Hospital of Fudan University and conducted in accordance with the ICH guidelines for Good Clinical Practice and the Declaration of Helsinki. All of the subjects in the study signed an informed consent form. Air-and bone-conduction ABR measurementAir-and bone-conduction ABRs were performed in a soundproof room. All test subjects orally received 0.5 ml/kg dose of 10% chloral hydrate to induce a 'deep' sleep. Air-and bone-conduction ABRs were measured with a GSI Audera Brainstem Analyzer using Model TDH-39P headphone and AD229 earphone, respectively. Silver disc electrodes were placed on the forehead (active), nasion (ground), and earlobe (reference) for air-conduction ABR. When bone-conduction was performed, the AD299 earphone was placed on the mastoid bone without moving the reference electrode. The band pass filter settings were 100 and 2500 Hz (bone ABR, 50-1500 Hz) with a 10 Ms window