Bruce A. Weber

Auditory and Visual Evoked Responses in Children with Familial Reading Disabilities

Amplitudes of auditory and visual evoked responses from right and left hemispheres were compared in subjects from three families having more than one person with reading problems. Contrary to expectations, the dyslexic members of these families did not demonstrate a flattening of the evoked responses over the left hemisphere Furthermore, there were no differences between dyslexic and normal members of the same family. Investigation of dyslexic children from 18 additional families also demonstrated no systematic alteration of the evoked responses over the left hemisphere. Although some degree of hemispheric asymmetry cannot be ruled out completely, measurement of evoked responses appears to have little diagnostic value, at present, in the evaluation of individual children or families.

Auditory brain stem responses of premature infants to bone-conducted stimuli: a feasibility study

The feasibility of bone conduction auditory brain stem response (ABR) audiometry in intensive care nursery neonates was investigated. Forty premature infants were tested with both air- and bone-conducted stimuli. Bone-conducted stimuli resulted in more identifiable ABRs and a greater number of subjectes passing the hearing screening. The findings of this study suggest that bone conduction ABR audiometry is a feasible technique with premature infants. Due to the lower frequency composition of the bone-conducted click, it may be more effective than an air-conducted click when the immature cochlea is being evaluated.

Comparison of Auditory Brain Stem Response Latency Norms for Premature Infants

Two investigations were conducted in an attempt to devise an improved set of auditory brain stem response (ABR) latency norms for premature infants. The first study utilized the responses of 130 infants to develop conventional ABR wave V latency norms for different conceptual ages. In addition, three sets of alternative norms were devised which utilized both waves 111 and V and used ABR interwave intervals as measures of brain stem maturation. A second study examined how well each of the four sets of latency norms predicted the ABR latencies of an additional group of 131 normal-hearing infants. The results of this second study demonstrated that norms utilizing wave 111 and the 1–111 interwave interval as an indicator of brain stem maturation were more sensitive than conventional norms, which provide expected wave V latencies for different conceptual ages.

Quantifying Click Stimuli in Auditory Brainstem Response Audiometry

The calibration of the abrupt click stimulus used in auditory brainstem response audiometry presents some unique problems. This report describes the critical aspects of the click stimulus (intensity, waveform, polarity, and spectrum) and relates them to possible contamination of auditory brainstem response test results. Techniques for measuring and reporting click stimulus parameters are also discussed.

Use of CNS Stimulant Medication in Averaged Electroencephalic Audiometru with Children with MBD

Averaged electroencephalic audiometry (AEA) was conducted on 12 children diagnosed as having minimal brain dysfunction (MBD). Each child was tested on three separate days to permit a double-blind evaluation of responsiveness to no-drug, placebo and CNS stimulant drug conditions. In addition, 9 of the 72 children were tested a fourth time to permit an examination of the two dosage levels. Lower thresholds were recorded when the subjects were tested on medication. This finding suggests that AEA with MBD children can be enhanced by taking advantage of the medication prescribed to counteract hyperactivity. It was also observed that the AEA performance of children on whom medication had a favorable behavioral effect was different from that of poor drug responders, even in the no-medication conditions.

Effects of response requirements on the location of clicks superimposed on sentences.

Two methods of identifying the location of clicks superimposed on sentences were compared. When Ss first wrote out the entire sentence and then marked the location of the clicks, the perceived clicks tended to migrate toward the major constituent breaks of the sentences. This trend was not observed when Ss responded by marking the position of clicks on prepared scripts of the stimulus sentence. In addition, both response procedures resulted in a significant trend for the perceived clicks to be located before the actual click locations. The findings of this study resolved the conflicting results obtained from previous investigations in this area.

Pitfalls in Auditory Brain Stem Response Audiometry

ABR audiometry is now a widely used clinical procedure. Although the technique provides valuable information about peripheral hearing status and assists in the detection of a retrocochlear lesion, it possesses a number of pitfalls which may not be readily apparent. This report discusses some of the limitations and problem areas in ABR audiometry.

Assessing low frequency hearing using auditory evoked potentials.

The difficulties involved in the behavioral audiometric evaluation of very young, multiply handicapped and uncooperative children are well known to audiologists. When attempts at performing behavioral audiometry are unsuccessful, testing with auditory evoked potentials is the next logical step because its success is not dependent upon the child’s cooperation or understanding of instructions. Though not a replacement for behavioral audiometry, electrophysiologic testing can provide useful information about hearing status which the audiologist can use to determine better the need for further behavioral testing. Through the years a number of auditory evoked potentials have been used for this purpose. Currently, however, there is wide agreement that the single most useful measure is the auditory brain stem response (ABR).

Influence of electrode impedance on auditory brain stem response recordings in the intensive care nursery.

ABR results from 400 newborns were examined for skin contact-electrode impedance effects on screening results. Neither high electrode impedance nor unbalanced impedance between the active electrodes appeared to have a significant effect on the screening results. Caution is advised in interpreting the results of this study. The authors are not advocating poor skin-electrode contact. However, satisfactory responses have been recorded with higher than previously reported optimal electrode impedance.