Neonate Auditory Brainstem Responses to CE-Chirp and CE-Chirp Octave Band Stimuli I: Versus Click and Tone Burst Stimuli

Audiogram Estimation by Auditory Brainstem Response with NB CE-Chirp LS stimulus in Normal Hearing Infants

Introduction  NB CE-Chirp LS was developed to improve the audiogram estimation by auditory brainstem response (ABR) thresholds during audiological assessment of infants and difficult to test children. However, before we know how the stimulus behaves in several types of hearing loss, it is important we know how the stimulus behaves in normal hearing infants. Objective  To describe ABR thresholds with NB CE-Chirp LS stimulus for 500, 1,000, 2,000, and 4,000 Hz, as well as the amplitude and absolute latency for ABR thresholds. Methods  Auditory brainstem response thresholds were evaluated with the Eclipse EP25 system. NB CE-Chirp LS was presented using an ER-3A insert earphone. EEG filter was 30 Hz high-pass and 1,500 Hz low-pass. The ABR threshold was defined as the lowest intensity capable of clearly evoke wave V, accompanied by an absent response 5 dB below. Results  Eighteen normal hearing infants were evaluated. The mean and standard deviation (SD) of the ABR threshold (dB nHL) were: 23.8 (±4.2); 14.4 (±5.7); 6.0 (±5.0); and 7.0 (±5.9). The mean and SD of the absolute latency (ms) were: 8.86 (±1.12); 9.21 (±0.95); 9.44 (±0.78); and 9.64 (±0.52). The mean amplitude (nV) and SD were: 0.123 (±0.035); 0.127 (±0.039); 0.141 (±0.052); and 0.105 (±0.028), respectively, for 500, 1,000, 2,000 and 4,000 Hz. Conclusion  Auditory brainstem response threshold with NB CE-Chirp LS reaches low levels, in special for high frequencies. It provides absolute latencies similar between frequencies with robust amplitude. The results obtained brings to the examiner more confidence in the results registered.

Investigating the Effects of Level-Specific CE-Chirp on Auditory Brainstem Response Waves in Normal Hearing Infants

Background

Auditory brainstem response (ABR) to the level-specific (LS) CE-Chirp has been reported to provide optimum neural synchrony along cochlear partitions, theoretically improving ABR waveform resolution. Despite this promising finding, limited studies have been conducted to contrast the results between LS CE-Chirp and Click stimuli. The current study aimed to compare the results of ABR between the two stimuli (Click and LS CE-Chirp).

Method

Sixty-seven normal-hearing infants, both with and without risk factors, aged less than 7 months old, participated in this study. The ABR test was conducted at 70 dBnHL using 33.3 stimulus repetition rates with both Click and LS CE-Chirp stimuli. The signal averaging was stopped at a maximum fixed signal average of 2,500 sweeps. Data were statistically compared between the two stimuli using the Wilcoxon signed-rank test.

Results

The waves I and V ABRs elicited by LS CE-Chirp exhibited significantly larger amplitudes than the Click stimulus. However, the amplitude of wave III and absolute latencies were similar in both stimuli at a supra-threshold level.

Conclusion

LS CE-Chirp has the advantage of larger amplitudes than the ABR from Click at the supra-threshold level (70 dBnHL) in normal-hearing infants.

Which stimulus should be used for auditory brainstem response in newborns; CE-Chirp® level specific versus Click stimulus

OBJECTIVES

Auditory Brainstem Response (ABR), the electrical responses in the neuronal pathways extending from the inner ear to the auditory cortex, are evaluated with auditory stimuli. ABR analysis evaluates waves I, III and V's absolute-latencies, amplitude values, interpeak-latencies, interaural-latency differences, and morphologies. This study aims to reveal the advantages of CE-Chirp® LS stimulus and its clinical uses to increase by comparing the amplitude, latency, and interpeak-latency differences of waves I, III, and V at 80 dB nHL and wave V at 60, 40, 20 dB nHL by using click and CE-Chirp® LS stimuli.

METHODS

100 (54 boys, 46 girls) infants with normal hearing were included in the National Newborn Hearing Screening Program. With the click and CE-Chirp® LS ABR, the absolute latency and amplitude values of wave V at 20, 40, and 60 dB nHL, and the absolute-latency, interpeak-latency, and amplitude values of waves I, III, and V at 80 dB nHL are determined between stimuli and right-left ear.

RESULTS

When the wave V latency and amplitudes obtained at 80, 60, 40, and 20 dB nHL levels were examined between genders, and according to the risk factor, no significant difference was found between click and CE-Chirp® LS stimuli (p > 0.05). Waves I, III, and V absolute-latency, amplitudes were compared at 80 dB nHL and wave V absolute-latency, amplitudes at 60, 40, and 20 dB nHL; the amplitudes measured with CE-Chirp® LS were significantly higher than the click stimulus (p < 0.05). When two stimuli were compared for I-III and III-V interpeak-latency values at 80 dB nHL level, no significant difference was found between the two stimuli (p > 0.05). However, the I-V interpeak-latency value was statistically significantly decreased for two stimuli, regardless of the ear (p < 0.05).

CONCLUSIONS

It is suggested to increase the use of CE-Chirp® LS stimulus with better morphology and amplitude in clinics, believing that it facilitates clinicians' interpretation.

Auditory Brainstem response electrophysiological thresholds with narrow band chirps stimuli in hearing infants

OBJECTIVES

to describe reference values for the electrophysiological thresholds obtained in the frequency-specific Auditory Brainstem Response (fsABR) with the NB CE-Chirp® LS and NB iChirp stimuli in hearing infants and to compare the variables: Minimum Levels of Response (MLR), latency, amplitude and examination time.

METHODS

the sample consisted of 74 full-term infants, with a mean age of 23.11 days, 29 females and 45 males. The participants underwent fsABR at the frequencies of 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz, to measure the MLR with the NB CE-Chirp® LS stimulus in the Eclipse equipment, and with the NB iChirp stimulus in the SmartEP, all in natural sleep and performed in the same session. The waveforms were evaluated by judges and later, for the comparison of thresholds and examination time, analyzed with the Wilcoxon test. To compare latency and amplitude, the Student's T Test and ANOVA were used for the same variables, but with the same stimulus. The Kruskal-Wallis test was used to compare the examination time at the different frequencies.

RESULTS

The MLR and latency at 500 Hz and 1000 Hz showed a statistically significant difference between the stimuli, with lower thresholds and higher latencies for the NB iChirp. Higher amplitudes were obtained with the NB iChirp stimulus. The average examination time for the threshold investigation in the four frequencies was 40 min for each ear.

CONCLUSION

it was possible to present reference values for the MLR and latencies for the NB CE-Chirp® LS and NB iChirp stimuli for hearing infants. In addition, with the NB iChirp, the latency of the responses was influenced by the frequency, but it was the stimulus that provided greater amplitudes. With the NB CE-Chirp® LS, the frequency did not influence latency, except at 500 Hz, and the stimulus provided recordings that facilitated the visualization of wave V. There was no difference in the examination time between the stimuli, nor between the test frequencies.

Auditory Brainstem Response with the iChirp stimuli in the infant's audiological diagnosis

OBJECTIVE

to investigate the use of the iChirp stimulus in the infant's audiological diagnosis compared to stimuli typically used in the ABR in infants, in addition to suggesting reference values for the assessment of this population.

METHODS

62 infants participated in the study, 29 females and 33 males. The subjects underwent the recording of the Auditory Brainstem Response in the Smart Ep equipment, with the stimuli click, iChirp-broadband, tone burst and iChirp-narrowband, which were presented at three levels of intensity (20 dB, 40 dB and 60 dB) and, for tone burst and iChirp-narrowband stimuli, at different frequencies (0.5, 1 k, 2 k and 4 KHz). The data were later analyzed using Student's t-test.

RESULTS

In general, the iChirp-broadband and iChirp-narrowband stimuli showed higher latency values and greater amplitudes when compared to click and tone burst stimuli. Furthermore, better signal-to-noise ratios were observed when contrasting iChirp-narrowband with tone burst. Additionally, reference values were established for the assessment of ABR in infants with the iChirp-broadband and iChirp-narrowband in the Smart-Ep equipment.

CONCLUSION

The iChirp stimulus appears to be promising in the infant's audiological diagnosis, as its use promoted greater amplitudes and better wave morphology, which facilitates to mark the waveforms and provides greater efficiency in the investigation of the auditory thresholds. The indication of normative data also enables the clinical use of these stimuli in the infant's audiological diagnosis.

Considerations for Fitting Cochlear Implants Bimodally and to the Single-Sided Deaf

When listening with a cochlear implant through one ear and acoustically through the other, binaural benefits and spatial hearing abilities are generally poorer than in other bilaterally stimulated configurations. With the working hypothesis that binaural neurons require interaurally matched inputs, we review causes for mismatch, their perceptual consequences, and experimental methods for mismatch measurements. The focus is on the three primary interaural dimensions of latency, frequency, and level. Often, the mismatch is not constant, but rather highly stimulus-dependent. We report on mismatch compensation strategies, taking into consideration the specific needs of the respective patient groups. Practical challenges typically faced by audiologists in the proposed fitting procedure are discussed. While improvement in certain areas (e.g., speaker localization) is definitely achievable, a more comprehensive mismatch compensation is a very ambitious endeavor. Even in the hypothetical ideal fitting case, performance is not expected to exceed that of a good bilateral cochlear implant user.

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

OBJECTIVES

The object of this study was to examine if caesarean section delivered neonates have different middle ear function relative to neonates with vaginal delivery.

METHODS

Auditory 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.

RESULTS

Statistically 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).

CONCLUSIONS

The 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.

Neonate auditory brainstem response repeatability with controlled force gauge bone-conducted stimulus delivery

OBJECTIVE

The feasibility and repeatability of neonate auditory brainstem responses (ABRs) with a controlled hand-held applied force gauge for bone-conducted stimulus delivery was examined.

DESIGN

A repeated measures test-retest design was employed.

STUDY SAMPLE

Participants were 27 healthy neonates. A 4000 Hz bone-conducted CE-Chirp octave band stimulus evoked the ABRs. Intra- and intertester conditions were employed with a prototype hand-held applied force gauge (Etymōtic Research) attached to the superior aspect of the bone vibrator. The bone vibrator was placed in a superoposterior auricular position and held manually. The force gauge displayed a desired coupling force via an LED light indicator.

RESULTS

Three sets of replicated ABRs were recorded from all neonates: initial test and retest with one tester (i.e. intratester 1 and 2) and final test with a second tester (i.e. intertester). No significant differences in intra- or intertester ABR wave V latencies or amplitudes were found (p > 0.05). Coefficients of reliability (Cronbach's α) were .95 and .43 for wave V latencies and amplitudes, respectively.

CONCLUSIONS

A hand-held applied force gauge may be a reliable means of delivering controlled bone-conducted stimuli in ABR assessments in neonates and infants.

Device optimised chirp stimulus for ABR measurements with an active middle ear implant

OBJECTIVE

Active middle ear implants are widely used to treat adults and children with sensorineural, conductive, or mixed hearing loss. Currently, there is no adequate method to determine the performance of active middle ear implant systems.

DESIGN

The proposed method is based on measuring the auditory brainstem response while stimulating the hearing system via the active middle ear implant (Vibrant Soundbridge^TM, VSB; MEDEL, Austria). The acoustic stimulation was achieved via an optimised chirp stimulus (CE-Chirp), implemented in the Eclipse system (Interacoustics, Denmark). To compensate for the frequency-specific delays in the VSB system, the underlying model function of the CE-Chirp was adjusted accordingly (VSB-CE-Chirp). Study samples: The study includes 12 subjects having mild to profound sensorineural, conductive or mixed hearing loss.

RESULTS

The use of an optimised VSB-CE-Chirp instead of the CE-Chirp increases significantly the ABR wave V amplitudes (1.63 times) and so also increases their identifiability (by 15.2%). On average, wave V could be identified at a 7.5 dB lower stimulation level.

CONCLUSION

The constructed VSB-CE-Chirp stimulus, after it had been transmitted through the VSB system, follows well the shape of the original CE-Chirp. Preliminary measurements in VSB patients demonstrated a significantly improved ABR amplitude with the VSB-CE-Chirp.