Noise effective masking level for bone conduction of wide-spectrum short-duration signals in normal hearing adults.

OBJECTIVE: The objective of this study is to determine the noise effective masking level (EML) and inter-aural attenuation (IA) for click and CE-Chirp signals presented though a Radioear B-81 to elicit the auditory brainstem responses in normally hearing, young adults. DESIGN AND STUDY SAMPLE: A total of 26 conveniently sampled adults (13 male and 13 female, aged 18-25 years; 52 ears), with pure-tone hearing thresholds not >15 dB nHL at octave frequencies from 250 to 8000 Hz, and subjective thresholds for the bone-conducted click and CE-Chirp not >10 dB nHL. RESULTS: At stimulus intensities of 30 and 40 dB nHL, the contralateral EML was 67.86 ± 0.78 and 77.80 ± 0.81 dB SPL (respectively) for the click and 72.11 ± 0.74 and 83.53 ± 0.78 dB SPL (respectively) for the CE-Chirp. At stimulus intensities of 30 and 40 dB nHL, the IA was 3.46 ± 2.34 and 3.38 ± 2.03 dB (respectively) for both the click and the CE-Chirp. CONCLUSION: EML and IA values are reported for click and CE-Chirp signals presented at 30 and 40 dB nHL though a Radioear B-81 to elicit the ABR in normally hearing, young adults.

Unilateral auditory neuropathy spectrum disorder.

CONCLUSIONS: The majority of the patients with unilateral auditory neuropathy spectrum disorder (UANSD) were pediatric and mostly showed a great degree of hearing loss when diagnosed. Abnormal auditory brainstem response (ABR) and preserved otoacoustic emissions (OAEs) and/or cochlear microphonics (CM) were important features to differentiate it from common sensorineural deafness and central nerve hearing loss. OBJECTIVE: To identify the clinical characteristics of patients with UANSD. METHODS: This was a retrospective study involving 14 patients diagnosed as having UANSD between 2004 and 2010 in the Chinese PLA Hospital. RESULTS: In all, 50% of the cases were males (1:1 sex ratio) and the average age of onset was 4.1 years. Of the 14 affected ears with UANSD in these cases, 6 were left-sided, while 8 were right-sided. Of the 14 contralateral ears, 4 presented with sensorineural hearing loss, while the other 10 showed normal hearing. The degree of hearing loss in the 14 affected ears varied, including moderate in 1, moderately severe in 4, severe in 5, and profound in 4. ABRs were absent in the 14 affected ears, while the OAEs, and/or CM were present.

Characteristics of cochlear microphonics in infants and young children with auditory neuropathy.

CONCLUSIONS: Cochlear microphonics (CMs) play an important role in the diagnosis of auditory neuropathy (AN). It is necessary and helpful to diagnose the sites-of-lesion in infants and children with AN by analyzing the patterns of CM amplitudes and I/O functions together. OBJECTIVES: To investigate the characteristics and clinical significance of CMs in the diagnosis of AN among infants and children. METHODS: A total of 36 infants and children (16 males and 20 females) were divided into two groups. Group A included 15 children (30 ears) with auditory brainstem response (ABR) absent and distortion product otoacoustic emissions (DPOAEs) present and group B included 21 children (30 ears) with ABR absent and DPOAEs absent. Fifteen normal-hearing infants (30 ears) made up the control group. Click eliciting CMs were recorded at stimulus levels of 100, 90, 80, and 70 dB nHL for each ear using a button electrode placed at the top of the forehead. A tube-clamping method was used to distinguish CMs from artifacts, and an averaging algorithm was used to obtain a clear CM waveform. The time delay and amplitude of CMs were measured in both children with AN and normal-hearing infants on (C-R)/2 waveforms, and an I/O function curve for each group was plotted with the stimulating level as input and the CM amplitude as output. RESULTS: The largest identifiable CMs were generally found between 0.5 and 0.8 ms after stimulation with mean delay of 0.63 ± 0.04 ms in both group A and the control group, and 0.63 ± 0.07 ms in group B. There was no significant difference between the AN group and the control group in CM time delay. There was no significant difference (p > 0.05) between group A (AN with OAEs present, 0.47 ± 0.15 µV) and the control group (0.45 ± 0.13 µV) in CM amplitude, while CM amplitudes in children with AN with DPOAEs absent (0.24 ± 0.08 µV) were significantly lower than those in either the control group or group A (p < 0.01). The amplitude of CMs reduced with stimulus intensity in all the subjects. There was obvious nonlinearity in group A and the control group, while there was a more linear tendency in amplitude increasing on the I/O function curve in group B.

[Correlation between phonetically balanced maximum and pure tone auditory threshold among 106 auditory neuropathy patients].

OBJECTIVE: To estimate correlation between phonetically balanced maximum (PB max) and pure tone auditory threshold in auditory neuropathy (AN) patients. METHODS: One hundred and six AN patients were identified using multiple criteria including PB max, a metric for speech recognition, pure tone auditory threshold, acoustic emission test, distortion products otoacoustic emission (DPOAE) and auditory brainstem response (ABR). SPSS statistical software was used to estimate the Pearson's correlation between PB max and pure tone auditory threshold and to test whether pure tone auditory threshold, or auditory configuration had a significant impact on PB max. RESULTS: Even the patients had the same or similar values for pure tone auditory threshold or auditory configuration, varied values of PB max were found in two hundreds and twelve ears for 106 patients. Analysis of the data for 106 patients revealed a negative correlation (r = -0. 602, P <0. 01) between PB max and pure tone auditory threshold, i. e. hearing loss at a mild relates to a lower PB max. By using analysis of variance (ANOVA) method, it was found that both pure tone auditory threshold and auditory configuration had a significant (P <0.01) impact on the patients' PB max. CONCLUSIONS: This analysis implicated the promise and potential of pure tone auditory threshold and auditory configuration for predicting PB max of the AN patients, and improving the diagnosis of AN.