Auditory Brainstem Response Protocol Research Articles

Rapid hearing threshold assessment with modified auditory brainstem response protocols in dogs.

Auditory brainstem response (ABR) is the gold standard for hearing testing in dogs. ABR is commonly used in puppies to diagnose congenital sensorineural deafness. Long test times limit the use for a more comprehensive hearing screening in veterinary practice. This study aimed to establish a super-fast hearing screening protocol in dogs. Hearing thresholds were routinely measured with a mobile device designed for newborn hearing screening in 90 dogs. We introduced modifications of the ABR protocol, e. g., a binaural test mode, higher stimulus rates, a broadband chirp stimulus, and an algorithm for automatic peak V detection in a stepwise fashion. Hearing thresholds were then measured with fast protocols utilizing either 30 Hz click or 90 Hz broadband chirp stimuli with 80, 60, 40, 30, 20, 10, 0 and -10 dBnHL stimulation intensities. Interrater reliability, agreement between click and chirp hearing thresholds and correlations with clinical characteristics of the dogs were assessed. Using all innovations, the test time for hearing threshold assessment in both ears was reduced to 1.11 min (mean). The chirp stimulus accentuated both, peak V and the subsequent trough, which are essential features for judgement of the hearing threshold, but preceding peaks were less conspicuous. Interrater reliability and agreement between click and chirp hearing threshold was excellent. Dogs >10 years of age and dogs with abnormal hearing score or otitis score had significantly higher hearing thresholds than younger dogs (p ≤ 0.001) or dogs without abnormalities (p < 0.001). The results demonstrate that modifications in ABR protocols speed-up test times significantly while the quality of the recordings for hearing threshold assessment is maintained. Modified ABR protocols enable super-fast hearing threshold assessment in veterinary practice.

Key Challenges and Future Directions When Running Auditory Brainstem Response (ABR) Research Protocols with Newborns: A Music and Language EEG Feasibility Study.

Although many musical intervention studies exist in the wider framework of neuroscience and psychology, the preliminary importance of feasibility studies is rarely discussed. Adding to this fact the limited research existing on the therapeutic and restorative potential of music exposure during early developmental periods, pushed us to concentrate on investigating newborns’ perception of music and its impact on the brain. Here, we explore the feasibility of a randomized controlled trial (RCT) approach when measuring and comparing the neurophysiological perception of music versus language on the brainstem of newborns using auditory brainstem response (ABR). Twenty-five healthy full-term infants were recruited, eight of which were measured within their first 10 days postpartum. The evaluation of the study’s feasibility appealed to five main objectives that essentially answer the question: Can our protocol work? Each objective proposes questions based on Orsmond and Cohn’s guiding framework, designed to assess, and assist feasibility in understanding barriers toward a study’s success. Our results justify that newborns are well capable of undergoing the study and given meticulous considerations and improvements on the intervention resources. The procedure’s communication and technical obstacles are resoluble. Moreover, assimilation of external factors to adapt, such as the culture variation and the ABR protocol implementation are necessary. The study was well received in the selected region (Middle East), and the recording procedure showed potential outcomes for a comprehensive RCT.

Hearing screening outcome in neonatal intensive care unit graduates from a tertiary care centre in Singapore.

We aimed to analyse the outcome of universal newborn hearing screening (UNHS) and high-risk hearing screening in neonatal intensive care unit (NICU) graduates in a tertiary care unit. The hearing screen programme comprises a 2-stage automated auditory brainstem response protocol followed by a high-risk hearing screen at 3-6 months. This study is a retrospective study of NICU graduates born between April 2002 and December 2009. Data on hearing screening, audiological assessment, and management were extracted from a computerized data management system (HITRACK). Of 100,225 newborn infants, 2.9% were admitted to the NICU during the study period. The overall incidence of hearing loss (HL) of any type/severity was 35/1,000 infants. Of infants with HL, 92.4% had their first automated auditory brainstem response at/before 1 month of corrected age. The incidence of congenital permanent HL identified by the UNHS was 15.4/1,000. The corrected median age of diagnosis was 4.5 months (1-23.5 months). Of 2,552 NICU graduates who passed the UNHS, 75.5% were retested at 3-6 months of life. Twelve infants with permanent late-onset HL were identified, raising the overall incidence of permanent HL to 19.9/1,000; 1.1/1,000 had auditory neuropathy. Of the 92 infants with HL, 89 (96.7%) had multiple risk factors. There is a high incidence of HL in NICU graduates; 22.6% were late in onset. An early rescreen in those who pass the UNHS is a beneficial step for this high risk population.

The British Columbia's Children's Hospital Tone-Evoked Auditory Brainstem Response Protocol: How Long Do Infants Sleep and How Much Information Can Be Obtained in One Appointment?

There are few published reports providing quantitative information of clinical feasibility for tone-evoked auditory brainstem response (ABR) protocols. In this study, the authors reviewed charts of 188 ABR assessments during a 20-mo period: 116 sedated (median age, 23 mos) and 72 nonsedated (median age, 4 mos). Fifty-one percent of infants had normal thresholds. The average amount of sleep time was 58 mins for sedated assessments, during which an average of 7.6 measures were obtained; nonsedated assessments averaged 49 mins with 6.2 measures obtained. Thus, a substantial amount of both test time and information about hearing can be obtained within one ABR appointment.

Sound generated by a payao and comparison with auditory sensitivity of jack mackerelTrachurus japonicus

Sound generated by a payao, an anchored bamboo fish aggregating device, is believed to be attractive to fish; but until now, there is no available record of payao-generated sound. This study presents payao-generated sound recorded by a hydrophone at water depths of 5, 10 and 15 m from a fixed distance of 3 m relative to the payao, and compares the sound with the auditory sensitivity of jack mackerel Trachurus japonicus measured at discrete frequencies from 100 to 2000 Hz using the auditory brainstem response protocol. A consistent peak appeared in the sound spectrum at 49 Hz and showed an increasing sound pressure level with depth, which suggests that payao sound may come from the anchor rope. However, the contribution of the bamboo raft can not yet be discounted. The hearing threshold curve indicated that the most sensitive frequency range in jack mackerel is from 92.1 dB at 800 Hz to 111.0 dB at 200 Hz. These results show that the dominant frequency range of payao sound does not correspond with the high sensitivity frequency range of fish hearing.

Response to Sauter (2007)

Purpose To respond to the companion letter by T. B. Sauter (2007) commenting on “Initial Audiologic Assessment of Infants Referred From Well Baby, Special Care, and Neonatal Intensive Care Unit Nurseries” by R. K. Karzon and J. E. C. Lieu (2006). Method Sauter states that he is in agreement with the article by Karzon and Lieu with respect to the 2-hr time for the initial diagnostic appointment and the reliance on auditory brainstem response (ABR) as the primary method for threshold estimation in young infants. However, he questions the order of test stimuli within the ABR protocol and the order of tests within the test battery. Our comments reflect the clinical experience of the authors and are supported by evidence from the literature. Conclusions Development of a protocol for the initial evaluation of infants referred from newborn screening poses diagnostic challenges. A 2-hr appointment with a battery of tests works well with this population.

Threshold Prediction Using the Auditory Steady-State Response and the Tone Burst Auditory Brain Stem Response: A Within-Subject Comparison

The purpose of this study was to evaluate the accuracy with which auditory steady-state response (ASSR) and tone burst auditory brain stem response (ABR) thresholds predict behavioral thresholds, using a within-subjects design. Because the spectra of the stimuli used to evoke the ABR and the ASSR differ, it was hypothesized that the predictive accuracy also would differ, particularly in subjects with steeply sloping hearing losses. ASSR and ABR thresholds were recorded in a group of 14 adults with normal hearing, 10 adults with flat, sensorineural hearing losses, and 10 adults with steeply sloping, high-frequency, sensorineural hearing losses. Evoked-potential thresholds were recorded at 1, 1.5, and 2 kHz and were compared with behavioral, pure-tone thresholds. The predictive accuracy of two ABR protocols was evaluated: Blackman-gated tone bursts and linear-gated tone bursts presented in a background of notched noise. Two ASSR stimulation protocols also were evaluated: 100% amplitude-modulated (AM) sinusoids and 100% AM plus 25% frequency-modulated (FM) sinusoids. The results suggested there was no difference in the accuracy with which either ABR protocol predicted behavioral threshold, nor was there any difference in the predictive accuracy of the two ASSR protocols. On average, ABR thresholds were recorded 3 dB closer to behavioral threshold than ASSR thresholds. However, in the subjects with the most steeply sloping hearing losses, ABR thresholds were recorded as much as 25 dB below behavioral threshold, whereas ASSR thresholds were never recorded more than 5 dB below behavioral threshold, which may reflect more spread of excitation for the ABR than for the ASSR. In contrast, the ASSR overestimated behavioral threshold in two subjects with normal hearing, where the ABR provided a more accurate prediction of behavioral threshold. Both the ABR and the ASSR provided reasonably accurate predictions of behavioral threshold across the three subject groups. There was no evidence that the predictive accuracy of the ABR evoked using Blackman-gated tone bursts differed from the predictive accuracy observed when linear-gated tone bursts were presented in conjunction with notched noise. Similarly, there was no evidence that the predictive accuracy of the AM ASSR differed from the AM/FM ASSR. In general, ABR thresholds were recorded at levels closer to behavioral threshold than the ASSR. For certain individuals with steeply sloping hearing losses, the ASSR may be a more accurate predictor of behavioral thresholds; however, the ABR may be a more appropriate choice when predicting behavioral thresholds in a population where the incidence of normal hearing is expected to be high.

Establishing normal hearing with the dichotic multiple-frequency auditory steady-state response compared to an auditory brainstem response protocol

ObjectiveTo determine the clinical usefulness of the dichotic multiple-frequency (MF) auditory steady-state response (ASSR) technique for estimating normal hearing compared to a 0.5-kHz tone burst and broadband click auditory brainstem response (ABR) protocol in a sample of adults.Material and MethodsA comparative experimental research design was selected in order to compare estimations of normal hearing obtained with the dichotic ASSR technique at 0.5, 1, 2 and 4 kHz with a 0.5-kHz tone burst and broadband click ABR protocol. The recording times required for each procedure were also compared. Normal-hearing subjects (n = 28) were selected according to immittance values within normal limits and pure-tone behavioural thresholds of < 25 dB HL across frequencies.ResultsThe dichotic MF ASSR estimated normal hearing to be, on average, 30–34 dB HL across the range 0.5–4 kHz. The mean estimate of normal hearing for 0.5 kHz using tone burst ABRs was 30 dB nHL and the mean click ABR threshold was 16 dB nHL, i.e. 14–18 dB better than the ASSR thresholds. The dichotic MFASSR technique recorded 8 thresholds (4 in each ear) in a mean time of 23 min. The ABR protocol recorded 4 thresholds (2 in each ear) in a mean time of 25 min.ConclusionsBoth the dichotic MF ASSR and ABR protocols provided a time-efficient estimation of normal hearing. There was no significant difference between the tone burst ABR and MF ASSR techniques in terms of estimation of normal hearing at 0.5 kHz. The dichotic MF ASSR technique proved more time-efficient by determining more thresholds in a shorter time compared to the ABR protocol.

Effects of underwater noise on auditory sensitivity of a cyprinid fish

The ability of a fish to interpret acoustic information in its environment is crucial for its survival. Thus, it is important to understand how underwater noise affects fish hearing. In this study, the fathead minnow ( Pimephales promelas) was used to examine: (1) the immediate effects of white noise exposure (0.3–4.0 kHz, 142 dB re: 1 μPa) on auditory thresholds and (2) recovery after exposure. Audiograms were measured using the auditory brainstem response protocol and compared to baseline audiograms of fathead minnows not exposed to noise. Immediately after exposure to 24 h of white noise, five out of the eight frequencies tested showed a significantly higher threshold compared to the baseline fish. Recovery was found to depend on both duration of noise exposure and auditory frequency. These results support the hypothesis that the auditory threshold of the fathead minnow can be altered by white noise, especially in its most sensitive hearing range (0.8–2.0 kHz), and provide evidence that these effects can be long term (>14 days).

Identification of neonatal hearing impairment: auditory brain stem responses in the perinatal period.

1) To describe the auditory brain stem response (ABR) measurement system and optimized methods used for study of newborn hearing screening. 2) To determine how recording and infant factors related to the screening, using well-defined, specific ABR outcome measures. Seven thousand one hundred seventy-nine infants, 4478 from the neonatal intensive care unit (NICU) and the remaining from the well-baby nursery, were evaluated with an automated ABR protocol in each ear. Two channel recordings were obtained (vertex to mastoid or channel A and vertex to nape of neck or channel B) in response to click stimuli of 30 and 69 dB nHL in all infants as well as 50 dB nHL in infants who did not meet criteria for response at 30 dB. Criteria for response included F(SP) > or =3.1 and a tester-judgment of response. Criteria could be met in the first or repeat test with a maximum of 6144 accepted sweeps per test. More than 99% of infants could complete the ABR protocol. More than 90% of NICU and well-baby nursery infants "passed" given the strict criteria for response, whereas 86% of those with high risk factors met criterion for ABR response detection. The number of infants who did not meet ABR response criteria in one or both ears was systematically related to stimulus level with the largest group not meeting criteria at 30 dB followed by 50 and 69 dB nHL. Meeting criteria on the ABR was positively correlated with the amplitude of wave V, with low noise and low electrode impedance. Factors that predicted how many sweeps would be needed to reach criterion F(SP) included noise level of the test site, state of the baby (for example, quiet sleep versus crying), recording noise, electrode impedance and response latency. Channel A (vertex to mastoid) reached criterion more often than channel B (vertex to nape of neck) due to higher noise in channel B. Average total test time for 30 dB nHL screening in both ears was under 8 minutes. Well babies with risk factors took slightly longer to evaluate than other groups with this automated ABR procedure and have higher noise levels. ABR implemented with an automated detection algorithm using a 30 dB nHL click stimulus is reliable technique for rapid assessment of auditory status in newborns. Factors other than hearing loss that influenced the test result include infant state, electrode location and impedance, testing site, and infant risk status. Even so, ABRs were reliably recorded in the vast majority of babies under circumstances in which most babies are found in the perinatal period.

The otic gasbladder as an ancillary auditory structure in a mormyrid fish.

Mormyrid fishes use acoustic signals for long-distance communication and a weakly electric field for short-distance interaction. Mormyrids are unique in having an otic gasbladder attached directly to the saccule on each side of the inner ear. Karl von Frisch (1938) hypothesized that the tightly coupled otic gasbladder might aid mormyrid hearing. Using the mormyrid fish (Brienomyrus brachyistius), this study manipulated gas in the otic gasbladder to test this hypothesis and histological sections were made to examine the anatomical relationship between the gasbladder and inner ear. The hearing sensitivity curves (audiograms) were obtained with the auditory brainstem response protocol. Audiograms were obtained from normal fish and from fish in which gas was withdrawn from either one or two otic gasbladders. Removal of gas from one otic gasbladder did not result in a significant change in either hearing ability or acoustically evoked brainwaves as compared to the control fish. Bilateral deflation of the otic gasbladders led to significant threshold changes. Histological sections revealed a particularly close coupling between the otic gasbladder and the saccule chamber. These results support von Frisch's hypothesis that the otic gasbladders of mormyrids assist in underwater sound detection.

Otoacoustic emission criteria for neonatal hearing screening

Transient evoked otoacoustic emission measures are gaining acceptance as a technique in new-born hearing screening. At present a wide variety of pass–fail screening criteria are used in otoacoustic emission screening programs. In a study of 100 special care neonates and 35 well, full term babies, a number of screening criteria were examined for sensitivity and specificity characteristics when compared to a standard auditory brainstem response protocol. Results indicate that, for normal and special care neonates with a gestational age at test of 38–41 weeks, high sensitivity (>80%) could be obtained when a pass–fail criterion involving analysis of emission reproducibility, or emission reproducibility and emission response level, was set. Sensitivity was reduced for special care neonates who fell outside this age range. Specificity was found to be relatively low overall (always <65%) and may relate to clinical factors in special care neonates not investigated in this study.

Strategies for infant auditory brain stem response assessment.

The use of auditory brain stem response (ABR) represents a new dimension in auditory and neurological pediatric assessment. Because the ABR may be altered by stimulus and procedural variables, the lack of an established standard has reduced its clinical efficiency. This paper describes a suggested ABR protocol for infants. Included are stimulus and electrode considerations, measurement criteria, and procedures. In addition, ABR results are presented from 125 newborns ranging between 40 and 49 weeks gestational age. The effects of age and intensity on latency and amplitude are discussed.