Contralateral Acoustic Reflex Thresholds Research Articles

Neurodegenerative Diseases and the Auditory-Vestibular System

Neurodegenerative Diseases and the Auditory-Vestibular System

Does the short-term exposure to radiofrequency electromagnetic field originating from mobile phone affect auditory functions as measured by Acoustic Admittance and Evoked Otoacoustic Emission tests?

ABSTRACT Background Mobile phones constitute an important source of radiofrequency electromagnetic field (RF-EMF) for humans. Taking into account high sensitivity of sensory hair cells of the inner ear to endogenous and exogenous agents, the potential impact of mobile phone usage on auditory organs is of particular interest. Aim The aim of the study was to evaluate the impact of short-term exposure to RF-EMF generated by a mobile phone during 15-minute simulated phone call on human hearing as measured by Transient Evoked Otoacoustic Emission (TEOAE) and Acoustic Admittance Testing (AAT). Material and methods Within-subject study was performed on 23 healthy volunteers. All of the participants underwent TEOAE and AAT before and immediately after 15-minute simulated phone call with the use of a standard, modern smartphone. Analyzed parameters included: static compliance of tympanic membrane, middle ear pressure, ipsi- and contralateral acoustic reflex thresholds and percentage of signal reproducibility in TEOAE for exposed and non-exposed ear. Additionally, the results were compared in subgroups distinguished basing on self-reported sensitivity to RF-EMF originating from mobile phones. Results No statistically significant differences were identified between results of TEOAE and AAT before and after exposure, both in exposed and non-exposed ear. The results of EMF sensitive and non-sensitive subjects were comparable in all performed tests. Conclusions Short-term exposure to mobile phone electromagnetic field did not influence auditory functions as measured by Evoked Otoacoustic Emission test and Acoustic Admittance Testing.

Effects of familial Mediterranean fever on the middle ear

ObjectiveTo evaluate middle and inner ear function and hearing status of children with familial Mediterranean fever (FMF). MethodsWe assigned 56 patients with FMF to the study group and 52 healthy volunteers to the control group. The mean age of patients in the study and control groups were 10.10 ± 3.70 and 9.77 ± 3.74 years, respectively. Physical examination and hearing evaluation were performed in both groups. The audiological test battery included 226-Hz tympanometry, pure tone audiometric evaluation, acoustic stapedial reflex measurements, distortion product otoacoustic emission recording, and wide-band tympanometry assessment. ResultsThe groups were similar in age and sex ratio (p > 0.05 for both comparisons). Pure tone audiogram and distortion product otoacoustic emission results were also similar for both groups (p > 0.05). The ipsilateral acoustic stapedial reflex were present in both of the groups and all participants had Type A tympanogram. The contralateral acoustic stapedial reflex thresholds were significantly higher in the familial Mediterranean fever group (p < 0.05 for all comparisons). The ambient and peak pressure absorbance values of wide-band tympanometry were significantly lower at 2000 Hz and significantly higher at 4000 Hz in the familial Mediterranean fever group (p < 0.05 for both comparisons). The severity and duration of disease adversely affected the absorbance values of wide-band tympanometry at 2000 and 4000 Hz (p < 0.05). ConclusionTo our knowledge, this is the first study to demonstrate the adverse subclinical effects of familial Mediterranean fever on the middle ear. We recommend that children diagnosed with FMF should be closely monitored for future clinical middle ear pathologies.

Effect of Intensity Level and Speech Stimulus Type on the Vestibulo-Ocular Reflex.

Accurate vestibulo-ocular reflex (VOR) measurement requires control of extravestibular suppressive factors such as visual fixation. Although visual fixation is the dominant suppressor and has been extensively studied, the mechanisms underlying suppression from nonvisual factors of attention and auditory stimulation are less clear. It has been postulated that the nonvisual suppression of the VOR is the result of one of two mechanisms: (1) activation of auditory reception areas excites efferent pathways to the vestibular nuclei, thus inhibiting the VOR or (2) cortical modulation of the VOR results from directed attention, which implies a nonmodality-specific process. The purpose of this research was to determine if the VOR is affected by the intensity level and/or type of speech stimulus. A repeated measures design was used. The experiment was single-blinded. Participants included 17 adults (14 females, three males) between the ages of 18-34 years who reported normal oculomotor, vestibular, neurological, and musculoskeletal function. Each participant underwent slow harmonic acceleration testing in a rotational chair. VOR gain was assessed at 0.02, 0.08, and 0.32 Hz in quiet (baseline). VOR gain was also assessed at each frequency while a forward running speech stimulus (attentional) or a backward running speech stimulus (nonattentional) was presented binaurally via insert earphones at 42, 62, and 82 dBA. The order of the conditions was randomized across participants. VOR difference gain was calculated as VOR gain in the auditory condition minus baseline VOR gain. To evaluate auditory efferent function, the medial olivocochlear reflex (MOCR) was assayed using transient-evoked otoacoustic emissions (right ear) measured in the presence and absence of broadband noise (left ear). Contralateral acoustic reflex thresholds were also assessed using a broadband noise elicitor. A three-way repeated measures analysis of variance was conducted to evaluate the effect of frequency, intensity level, and speech type on VOR difference gain. Correlations were conducted to determine if difference gain was related to the strength of the MOCR and/or to the acoustic reflex threshold. The analysis of variance indicated that VOR difference gain was not significantly affected by the intensity level or the type of speech stimulus. Correlations indicated VOR difference gain was not significantly related to the strength of the MOCR or the acoustic reflex threshold. The results were in contrast to previous research examining the effect of auditory stimulation on VOR gain as auditory stimulation did not produce VOR suppression or enhancement for most of the participants. Methodological differences between the studies may explain the discrepant results. The removal of an acoustic target from space to attend to may have prevented suppression or enhancement of the VOR. Findings support the hypothesis that VOR gain may be affected by cortical modulation through directed attention rather than due to activation of efferent pathways to the vestibular nuclei.

Hidden hearing loss in children and adolescents with sickle cell anemia

ObjectiveTo evaluate the auditory system for hidden hearing loss (HHL) and its association with clinical variables and endothelial dysfunction (ED) in children and adolescents with sickle cell anemia (SCA). MethodsParticipants included 37 patients with stable SCA and 44 healthy controls (HC group) (aged 6–18 years) with hearing thresholds ≤ 20 dB (dB) were evaluated for pure tone audiometry, tympanometry, acoustic reflex, otoacoustic emission, and auditory evoked potentials. Laboratory analysis of the lipid profile, and C-reactive protein levels and endothelial function using ultrasonographic imaging of the brachial artery to assess flow-mediated dilation were performed. ResultsThe SCA group presented with a higher rate of increased contralateral acoustic reflex thresholds, compared to those in the HC group at all frequencies and in both ears (p < 0.05). There were significant differences in the brainstem auditory evoked potentials between the SCA and HC groups. In the SCA group, the waves III and V latencies were increased (p = 0.006 and 0.004 respectively), and the I-III and I-V interpeak intervals were longer (p = 0.015 and 0.018 respectively) than those in the HC group. There was no association between the audiological measures and clinical and metabolic variables and sickle cell anemia complications including endothelial function and therapy. ConclusionIn conclusion, our findings suggest that damage in the auditory system in SCA patients can be present involving retrocochlear structures, causing functional deficits without deterioration of auditory sensitivity.

A Large-Scale Examination of Veterans with Normal Pure-Tone Hearing Thresholds within the Department of Veterans Affairs

Department of Veterans Affairs (VA) audiologists have anecdotally reported examining numerous Veterans with normal pure-tone thresholds; however, the prevalence of these patients within the VA is unknown. The VA audiological data repository provides an ideal dataset to examine this group of Veterans. Knowing the prevalence of normal-hearing Veterans within the VA system is the first step to understanding the underlying referral patterns and clinical complaints of Veterans. Data repositories which capture data from both normal and impaired populations provide an indispensable view into hearing health care which can help to improve diagnosis and treatment of Veterans' hearing difficulties. Using the VA audiological data repository, this study aimed to (1) determine the prevalence of normal hearing thresholds among Veterans seeking hearing health care within the VA health care system and (2) determine the prevalence of abnormal clinical audiology test results among Veterans with normal hearing thresholds. This study was a large-scale retrospective, descriptive observational analysis of uploaded audiological records from the VA Denver Acquisition and Logistics Center audiological data repository encompassing visits that took place between April 1991 and June 2015. At the time of data extraction, there were 3,641,326 audiological records in the repository, with 2,322,771 unique individual records. The study sample was further restricted to include only individuals with normal hearing (n = 235,091), which was defined as pure-tone thresholds better than, or equal to, 25 dB HL at octave frequencies from 250 to 8000 Hz, bilaterally. Patients ranged from 19 to 90+ years of age. We describe the data using frequencies and percentages for categorical variables and means and standard deviations for continuous variables. In addition to hearing thresholds, the occurrence of abnormal results on other tests in the audiological test battery is also reported. We estimate the prevalence of normal hearing among all Veterans with records in the VA audiological data repository. Veterans with normal hearing were on average 37 yr old. The prevalence of Veterans with normal hearing thresholds visiting VA audiology clinics in the current hearing repository dataset was 10.12%. Overall, 41% of Veterans with normal pure-tone thresholds had other clinically abnormal audiological test results; for example, contralateral acoustic reflex thresholds (31.7%) and tympanometry (21.5%) had the highest rate of abnormal test results. Approximately one in ten Veterans seeking care within the VA healthcare system, and reported to the VA audiological data repository, has normal pure-tone hearing thresholds. This may be an underestimate of the true underlying prevalence of normal-hearing Veterans seeking audiology services at the VA because records with normal results were not consistently submitted to the repository. In addition, 41% of Veterans with normal pure-tone thresholds nonetheless presented with other audiological abnormalities. This study suggests that future work directed toward understanding referral patterns and clinical complaints of individuals who present to VA audiology clinics with normal hearing thresholds may be fruitful in the cause of improving diagnosis and treatment of Veterans' hearing difficulties.

Objective evaluation of binaural summation through acoustic reflex measures

Objective: A previous study [Rawool, V. W. (2016). Auditory processing deficits: Assessment and intervention. New York, NY: Thieme Medical Publishers, Inc., pp. 186–187] demonstrated objective assessment of binaural summation through right contralateral acoustic reflex thresholds (ARTs) in women. The current project examined if previous findings could be generalised to men and to the left ear. Design: Cross-sectional. Study sample: Sixty individuals participated in the study. Left and right contralateral ARTs were obtained in two conditions. In the alternated condition, the probe tone presentation was alternated with the presentation of the reflex activating clicks. In the simultaneous condition, the probe tone and the clicks were presented simultaneously. Binaural summation was calculated by subtracting the ARTs obtained in the simultaneous condition from the ARTs obtained in the alternated condition. Results: MANOVA on ARTs revealed no significant gender or ear effects. The ARTs were significantly lower/better in the simultaneous condition compared to the alternated condition. Conclusions: Binaural summation was 4 dB or higher in 88% of the ears and 6 dB or higher in 76% of ears. Stimulation of six out of the total 120 (0.5%) ears resulted in worse thresholds in the simultaneous condition compared with the alternating condition, suggesting binaural interference.

The Contralateral Acoustic Reflex Threshold Using Speech Stimuli: A Comparative Study

The acoustic reflex (AR) is a subject that has been highly studied in the field of audiology. In fact, the physiology of the AR has been debated about since the 16th century. Historically and clinically the AR has been elicited with pure tone stimuli. In the 1970’s and 1980’s different eliciting stimuli were experimented with, such as: broadband noise (BBN), highband noise (HBN), lowband noise (LBN) and speech stimuli. The amplitude modulation of speech has made it difficult to record the acoustic reflex threshold (ART) due to the artifact that it creates on the measuring machine. When ecological validity, or the ability of the findings of the research to be applied to real-life setting, is taken into account, speech signals are the most valid of all types of stimuli that have been used to elicit the AR. In this study, three concatenated speech stimuli were created from the NU-6 word list 1-A. The words for the NU-6 word list 1-A were concatenated together to create one long speech stimuli, this was done to eliminate the impact of the artifact created by the amplitude modulation that is caused by the pauses in speech. The focus of this study was to compare the contralateral ART using the speech stimuli as the eliciting stimuli for the ART with a pure tone stimulus and different noise stimuli. Together, the findings presented here provide evidence supporting the use of the speech stimuli when measuring the ART clinically. The findings also suggest potential application and further research opportunities for noise induced hearing loss caused by self-vocalizations and a potential correlation for pure tone versus speech ART when testing individuals with central auditory processing disorders.

Time course and frequency specificity of sub-cortical plasticity in adults following acute unilateral deprivation

Auditory deprivation and stimulation can change the threshold of the acoustic reflex, but the mechanisms underlying these changes remain largely unknown. In order to elucidate the mechanism, we sought to characterize the time-course as well as the frequency specificity of changes in acoustic reflex thresholds (ARTs). In addition, we compared ipsilateral and contralateral measurements because the pattern of findings may shed light on the anatomical location of the change in neural gain. Twenty-four normal-hearing adults wore an earplug continuously in one ear for six days. We measured ipsilateral and contralateral ARTs in both ears on six occasions (baseline, after 2, 4 and 6 days of earplug use, and 4 and 24 h after earplug removal), using pure tones at 0.5, 1, 2 and 4 kHz and a broadband noise stimulus, and an experimenter-blinded design. We found that ipsi- as well as contralateral ARTs were obtained at a lower sound pressure level after earplug use, but only when the reflex was elicited by stimulating the treatment ear. Changes in contralateral ARTs were not the same as changes in ipsilateral ARTs when the stimulus was presented to the control ear. Changes in ARTs were present after 2 days of earplug use, and reached statistical significance after 4 days, when the ipsilateral and contralateral ARTs were measured in the treatment ear. The greatest changes in ARTs occurred at 2 and 4 kHz, the frequencies most attenuated by the earplug. After removal of the earplug, ARTs started to return to baseline relatively quickly, and were not significantly different from baseline by 4–24 h. There was a trend for the recovery to occur quicker than the onset. The changes in ARTs are consistent with a frequency-specific gain control mechanism operating around the level of the ventral cochlear nucleus in the treatment ear, on a time scale of hours to days. These findings, specifically the time course of change, could be applicable to other sensory systems, which have also shown evidence of a neural gain control mechanism.

Evaluation of Acoustic Reflex and Reflex Decay Tests in Geriatric Group.

To determine average acoustic reflex thresholds in geriatric groups by assessing ipsilateral and contralateral acoustic reflex and reflex decay tests. A total of 25 elders between ages 65-84 years (74.3±5.4) and 25 individuals between ages 18-45 years (30.4±4.2) were recruited for the study. After ear, nose, and throat examination, ipsilateral and contralateral acoustic reflex thresholds at 500, 1000, 2000, and 4000 Hertz (Hz) were determined and a reflex decay test at contralateral 500 Hz was conducted. Ipsilateral acoustic reflex thresholds were obtained with high-frequency band, low-frequency band, and wide band noise, and the results were compared with ipsilateral acoustic reflexes at 500, 1000, 2000, and 4000 Hz. There was no statistically significant difference between the two groups in ipsilateral and contralateral acoustic reflex measurements at 500, 1000, 2000, and 4000 Hz (p>0.05). Negative reflex decay was obtained in all participants and no statistically significant difference between the two groups was observed in terms of reflex decay thresholds (p>0.05). Acoustic reflex with high-frequency band noise was observed in five of nine elders whose acoustic reflexes were not obtained at 2000 and 4000 Hz, whereas acoustic reflex with low-frequency band noise was observed in one of six elders who did not show reflexes at 500 and 1000 Hz. It was concluded that although some changes were observed due to age, middle ear and stapes muscles work normally in geriatric group. In the reflex decay test, reliable results were obtained at contralateral 500 Hz. Acoustic reflex measurements with low- and high-frequency band noise may also be used to assess middle ear functions.

High levels of sound pressure: acoustic reflex thresholds and auditory complaints of workers with noise exposure

IntroductionThe clinical evaluation of subjects with occupational noise exposure has been difficult due to the discrepancy between auditory complaints and auditory test results. This study aimed to evaluate the contralateral acoustic reflex thresholds of workers exposed to high levels of noise, and to compare these results to the subjects’ auditory complaints. MethodsThis clinical retrospective study evaluated 364 workers between 1998 and 2005; their contralateral acoustic reflexes were compared to auditory complaints, age, and noise exposure time by chi-squared, Fisher's, and Spearman's tests. ResultsThe workers’ age ranged from 18 to 50 years (mean=39.6), and noise exposure time from one to 38 years (mean=17.3). We found that 15.1% (55) of the workers had bilateral hearing loss, 38.5% (140) had bilateral tinnitus, 52.8% (192) had abnormal sensitivity to loud sounds, and 47.2% (172) had speech recognition impairment. The variables hearing loss, speech recognition impairment, tinnitus, age group, and noise exposure time did not show relationship with acoustic reflex thresholds; however, all complaints demonstrated a statistically significant relationship with Metz recruitment at 3000 and 4000Hz bilaterally. ConclusionThere was no significance relationship between auditory complaints and acoustic reflexes.

Wideband detection of middle ear muscle activation using swept-tone distortion product otoacoustic emissions.

The measurement of efferent-induced suppression of otoacoustic emissions (OAEs) using contralateral acoustic stimulation (CAS) is complicated by potential contamination by the middle ear muscle reflex (MEMR), particularly at moderate to high CAS levels. When logarithmically sweeping primaries are used to measure distortion product otoacoustic emissions, the level and phase of the primaries at the entrance of the ear canal may be monitored simultaneously along with the OAEs elicited by the swept-tones. A method of detecting MEMR activation using swept-tones is presented in which the differences in the primaries in the ear canal with and without CAS are examined, permitting evaluation of MEMR effects over a broad frequency range. A range of CAS levels above and below expected contralateral acoustic reflex thresholds permitted evaluation of conditions with and without MEMR activation.

Confusion Surrounds Pediatric Audiology Billing

You have accessThe ASHA LeaderBottom Line1 Jul 2014Confusion Surrounds Pediatric Audiology BillingIf there’s no code for new technology, how do you bill it? Three audiology organizations develop answers to frequently asked questions. Neela Swanson Neela Swanson Google Scholar More articles by this author https://doi.org/10.1044/leader.BML.19072014.26 SectionsAbout ToolsAdd to favorites ShareFacebookTwitterLinked In Billing for pediatric audiology services can cause confusion for various reasons: Codes don’t reflect current technology or a certain test has no specific billing code associated with it, for example. A new resource helps with these issues. Audiology reimbursement experts from ASHA, the Academy of Doctors of Audiology and the American Academy of Audiology developed an online set of questions and answers for clinicians who provide pediatric services. Here are excerpts from some of the questions and answers you will find (billing codes refer to Current Produral Terminology codes, © American Medical Association). Is speech audiometry included in the codes for conditioning play audiometry (92582) and visual reinforcement audiometry (9279)? Two characteristics differentiate CPT codes 92579 (VRA) and 92582 (CPA): the method of response reinforcement and the types of stimuli. These codes are historical and do not have detailed code descriptions. As such, payers have relied on traditional practice standards that were available at the time the codes were last reviewed. Historically, descriptions of VRA test procedures included both speech and tonal stimuli as part of the test protocol. In contrast, CPA test protocols included tonal stimuli but did not include speech stimuli. If a clinician completes CPA testing and performs speech measures as part of the evaluation, then the clinician can also report a code that best describes the speech measure—such as speech threshold audiometry (92555), select picture audiometry (92583) or speech audiometry threshold with speech recognition (92556). Can I use CPT code 92550 (Tympanometry and reflex threshold measurements) if I perform a 1000 Hz ipsilateral acoustic reflex screening along with tympanometry? CPT has defined acoustic reflex threshold testing (92568 and 92550) as including both ipsilateral and contralateral acoustic reflex threshold measurements. There is no CPT code for acoustic reflex screening. Only the tympanometry code (92567) would be allowed in this instance. If I perform threshold-search auditory brainstem response testing and auditory steady-state response testing on the same day, what procedures should I bill? ASSR is considered to be a type of auditory evoked potential test and does not have a specific CPT code. The comprehensive auditory evoked potential code (92585) is the most appropriate code for billing ASSR at this time. 92585 is a session-based code; it can be billed only once per day, even if both ABR and ASSR testing are completed on that day. An extended service modifier (-22) could be considered when both ABR and ASSR are completed on the same day. Detailed documentation of the justification for the extended service should be included in the patient’s medical record. Author Notes Neela Swanson is ASHA director of health care coding policy. [email protected] Advertising Disclaimer | Advertise With Us Advertising Disclaimer | Advertise With Us Additional Resources FiguresSourcesRelatedDetails Volume 19Issue 7July 2014 Get Permissions Add to your Mendeley library History Published in print: Jul 1, 2014 Metrics Downloaded 120 times Topicsasha-topicsleader_do_tagleader-topicsasha-article-typesCopyright & Permissions© 2014 American Speech-Language-Hearing AssociationLoading ...

Tinnitus and Normal Hearing: A Study on Contralateral Acoustic Reflex

The aim of this study was to evaluate the difference of the contralateral acoustic reflex (AR) threshold between adult subjects with hearing within clinically normal limits, with and without tinnitus. The study sample in this exploratory, descriptive, and comparative study comprised 40 female subjects who were evaluated: 20 had tinnitus and 20 formed the control group. The contralateral AR threshold was evaluated at the frequencies of 500, 1000, and 2000 Hz. Elevated or absent AR thresholds were found only in subjects with complaints of tinnitus. At all frequencies and in either ear, the median AR threshold was higher in the group that complained of tinnitus (100.0 dB; range = 95.0–100.0 dB) compared with the control group (90.0 dB; range = 86.3–95.0 dB; p < .01). There was a statistically significant difference ( p < .05) in the group with tinnitus, in each of the frequencies studied and in both the right and left ear. The results suggest that evaluation of the efferent system, through AR, could be an important tool for the differential diagnosis of tinnitus in patients whose hearing was within clinically normal limits.

Temporal Integration of the Contralateral Acoustic Reflex Threshold for a 1000 Hz Tonal Activator and Its Age-Related Changes

Previous research has noted an age effect on the temporal integration of the acoustic reflex for a noise activator. To determine whether the age effect earlier noted for a noise activator will be noted for a tonal activator. Comparison of ARTs of younger and older groups at activating stimulus durations of 12, 25, 50, 100, 200, 300, 500, and 1000 msec. Two groups of adults with normal-hearing sensitivity: one group of 20 young adults (ten males and ten females, ages 18-29 years, with a mean age of 24 years) and one group of 20 older adults (ten males and ten females, ages 59-75 years, with a mean age of 67.5 years). A significant main effect for duration was obtained. That is, as the duration increased, the acoustic reflex threshold for the 1000 Hz tonal activator decreased. The interactions of duration x age group and duration x hearing level were not significant. There was a nonsignificant main effect (p = .889) for the between-subjects factor of age. Results contradict the findings for broadband noise.

Acoustic Immittance in children without otoacoustic emissions

SummaryConsidering the hypothesis that middle ear changes can impair the recording of otoacoustic emissions, it is possible that absent otoacoustic emissions in infants could be associated with a light tympanometric change.AimTo study the association between transient otoacoustic emissions and changes in acoustic immittance measurements with 226Hz probe tone in neonates.MethodsCross-sectional contemporary cohort study. 20 infants with no transient otoacoustic emissions (study group) and 101 infants with transient otoacoustic emissions (control group), with ages ranged from birth to eight months, were assessed. Infants were submitted to: admittance tympanometry; contralateral acoustic reflex threshold with stimulus of 0.5, 1, 2, 4 kHz and broad band noise; transient and distortion product otoacoustic emissions. The auditory brain response was used to study the threshold in neonates without transient otoacoustic emissions.ResultsSignificant statistical differences were observed between the groups (p < 0.005), characterized by reduction in tympanometric configuration and increase acoustic reflex thresholds in the study group. These data suggest the occurrence of middle ear mild impairment in infants without transient otoacoustic emissions associated with normal auditory brain response.Conclusiontympanometry associated with acoustic reflex adds accuracy to the diagnosis of middle ear abnormalities.

Primer on Research: An Introduction

Primer on Research: An Introduction

Acceptable Noise Level, Phoneme Recognition in Noise, and Measures of Auditory Efferent Activity

Acceptable noise level (ANL) is unrelated to sentence recognition in noise but may be related to phoneme recognition in noise (PRN). Individual differences in efferent activity in medial olivocochlear bundle (MOCB) and acoustic reflex (AR) pathways may account for intersubject variability in ANL and PRN. Monotic and dichotic ANL, monotic PRN, contralateral suppression of transient evoked otoacoustic emissions, and ipsilateral and contralateral acoustic reflex thresholds were measured in 31 adults with normal hearing. Results indicate that monotic ANL and PRN are unrelated. Monotic and dichotic ANL are related, suggesting that nonperipheral factors mediate ANL. Intersubject variability in ANL cannot be accounted for by individual differences in MOCB or AR activation. Intersubject variability in PRN cannot be accounted for by individual differences in MOCB or contralateral AR activation. It may be influenced by the ipsilateral AR pathway. Efferent activity in the contralateral AR arc is correlated with efferent activity in the MOCB.

Wideband Energy Reflectance

Wideband Energy Reflectance

The prediction of hearing loss in persons with cerebral palsy using contralateral acoustic reflex threshold for broad-band noise.

The utility of R. Keith's (1977) method of screening for hearing sensitivity using the contralateral acoustic-reflex threshold (ART) for broad-band noise (BBN) was tested in persons with cerebral palsy (CP). Three groups of participants were included in this prospective study. The first group comprised 20 normal-hearing individuals without CP whose results were used as normative data. The second group comprised 16 participants with normal hearing and CP. The third group comprised 22 participants with sensorineural hearing loss and CP. The results of this study indicate that Keith's screening method employing ART for BBN can be used successfully in a population with multiple handicaps where a quick, inexpensive, readily available, and accurate method is needed.