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• A two-step ablation technique under visual control was used to clarify the possible sites of origin of the binaural interaction component (BIC) of the auditory brainstem-evoked response (ABR). The BIC is obtained by summing ABRs elicited by monaural clicks to each ear and subtracting this sum from the ABR elicited by binaural clicks. Among the results were the following: first, the ABR and the BIC remained virtually unchanged after collicular aspiration; second, after midsagittal section of the brainstem, both wave III in the ABR and the BIC were abolished. These results suggest that although the inferior colliculus is a powerful integrative center for the processing of binaural signals, the neural structures in the guinea pig necessary for the primary generation of the BIC must be located caudal to the colliculus, yet rostral to the medial nucleus of the trapezoid body.(Arch Otolaryngol 1981;107:164-168)

• Binaural interaction (BI) in brainstem-auditory—evoked responses (BSERs) was defined as any deviation from the predictions of a model that assumes two independent monaural BSER generators whose outputs are additive. Brainstem-auditory—evoked responses were recorded in response to right (R) monaural, left (L) monaural, and binaural click stimuli. The monaural BSERs were added to give the model's prediction (P) of binaurally evoked BSER (P = L + R), and this trace was then subtracted from the actual binaurally evoked response (B). The resultant difference trace (D = B − P) represents the derived Bl. In each of ten guinea pigs, a strong BI was present in the peak IV region (latency = 3.5 to 4.0 ms). This interaction is probably present with interaural intensity differences of up to 40 dB and interaural time differences of up to 3 ms. Preliminary studies suggest the presence of a similar phenomenon in human BSERs.(Arch Otolaryngol 105:391-398, 1979)

• The primary clinical utility of electrocochleography at the Louisiana State University Medical Center is the detection of hearing losses in children. This frequently requires the administration of a general anesthetic. Time required for this procedure could be shortened if stimuli were presented at a more rapid rate than the customary 10/s, provided the response amplitude is not significantly diminished by adaptation. The response amplitudes of 12 subjects were studied at stimulus rates of 10, 20, 40, and 80/s. An increase of response amplitude on the order of approximately 3:1 over the 10/s rate was found for the 80/s rate when the test interval for each was equal.(Arch Otolaryngol 104:551-554, 1978)

• A follow-up study of 35 children subjected to electrocochleography (Ecog) was conducted to determine (1) agreement of Ecog results with other audiometric measures obtained subsequently, and (2) accuracy of recommendations for patient management made on the basis of Ecog results. The latter was determined by parental experience, educational placement and achievement, and information from medical and paramedical personnel currently managing the children. These data indicate that Ecog test results are valuable in helping select between possible management alternatives in children who are not testable by behavioral means. However, discussion of two "problem" cases points to possible errors of management that could be made if Ecog results were the only available diagnostic information.

Otitis media affects nearly every child at some time; many children have mild-to-moderate hearing losses for prolonged periods. The effects of these losses on language and educational development may be significant; possible mechanisms are discussed. Especially in suboptimal listening situations, speech perception may be impaired by even a mild hearing loss. Patterns of imperception are predicted by comparison of composite audiometric data from children with middle ear effusions with speech power data, and by analysis of sound pressure waveforms of speech filtered to simulate the typical hearing loss of these patients. A new method of analysis of brain stem evoked responses, yielding response components attributable to binaural interaction, is reported. This and other evoked response techniques may be able to identify objective changes in auditory nervous system function attributable to relative sensory deprivation during development. Finally, directions for further research in this area are discussed.

Dichotic simultaneous and time-staggered speech perception data from four patients with temporal lobectomies are compared to results from over 100 normals. In these tests, two different nonsense syllables are given in competition, one to each ear. The syllables are presented simultaneously, then with time separations ranging from 15 to 500 msec. With simultaneous onset, normals showed right ear superiority; with time separations of 30 to 90 msec, normals showed a "lag effect," ie, better scores for the trailing stimulus. In sharp contrast, temporal lobectomy patients showed poorer contralateral ear function than ipsilateral ear function, and no lag effect. Comparing preoperative and postoperative scores, we see that postoperatively there is additional degradation of contralateral ear scores and enhanced ipsilateral ear function in dichotic listening. Patients with both left and right temporal lobectomies behaved similarly in this respect.

AMONG the advantages which may accrue from study of isolate populations is the delineation of previously unrecognized hereditary disorders, particularly those which are recessive. Because of their high level of inbreeding and their large families, study of Amish communities has disclosed a number of previously unknown entities. These include a form of dwarfism,1 a disorder of bile excretion,2 a syndrome of severe mental retardation, microphthalmos, and hypopigmentation,3 and several neurologic disorders.4,5 Also, the malformation affecting the female genito-urinary tract termed hydrometrocolpos has been shown to have a simple genetic basis in some instances.6In a survey of the mentally retarded among the Amish of Lancaster County, Pa, several "new" genetically distinct disorders have been uncovered.7 This report described four sibs affected with a syndrome consisting of cochlear deafness, myopia, and intellectual impairment. MATERIALS AND METHODS The case family was ascertained through Amish sources and

Competing rhyming pairs of both natural and synthetic speech were presented both monotically and dichotically to normal right-handed listeners. When the onsets of the words were simultaneous (±2½ msecs), the right ear scores were generally higher than the left ear scores. However, voiceless consonants were much more intelligible dichotically than voiced consonants, regardless of which ear received the voiceless consonant. When both consonants competed monotically, the difference between voiced and voiceless consonant perception was either reversed or markedly attenuated. An explanation based on lagging of the aperiodic-to-periodic transition of the voiceless CV is offered.

Three of four sibs were affected by a nonprogressive neural hearing loss and atypical atopic dermatitis. History, physical and neurological examinations revealed no causes other than familial for the hearing loss. Audiometric examinations suggested the hearing loss was cochlear in origin. A review of the literature describing types of familial hearing loss associated with skin disease showed no similar report. It is suggested that these three children have a type of recessive familial hearing loss differing from others in its association with atypical atopic dermatitis.

Twenty-four Negro and 21 white lower-class children, 8 to 9 years old, received the Wepman Auditory Discrimination Test in two forms. The experimental group of 10 whites and 12 Negroes received special feedback and reinforcement, while the control group of 11 whites and 12 Negroes simply received a second trial. The special instructions and feedback improved the discrimination scores of the Negro experimental subjects only. No change was observed in the control group subjects who received an unadorned second trial.

Hearing in mice has been difficult to measure behaviorally. With GSR as the basic tool, the sensitivity curve to pure tones in mice has been successfully outlined. The most sensitive frequency-intensity combination was 15 000 cps at 0-5 dB re: 0.0002 dyne/cm2, with responses noted from 1 000 to beyond 70 000 cps. Some problems of reliability of conditioning were encountered, as well as findings concerning the inverse relationship between the size of GSR to unattenuated tones and the sound pressure necessary to elicit conditioned responses at or near threshold. These data agree well with the sensitivity of single units of the eighth nerve of the mouse.

The unconditioned GSR’s elicited by tones of 60, 70, 80, and 90 dB SPL were largest in the mouse in the ranges around 10,000 Hz. The growth of response magnitude with intensity followed a power law (10.17 to 10.22, depending upon frequency) and suggested that the unconditioned GSR magnitude assessed overall subjective magnitude of tones to the mouse in an orderly fashion. It is suggested that hearing sensitivity as assessed by these means may be closely related to the spectral content of the mouse’s vocalization as well as to the number of critically sensitive single units in the mouse’s VIIIth nerve.

Three experiments show that the magnitude of the unconditioned GSR to tones of equal intensity is largest between 10,000 and 20,000 Hz and is a valid index of the frequency sensitivity of the mouse. These findings agree well with cochlear potential findings and single unit response areas, and suggest that the magnitude of the unconditioned GSR might be used as a screening device for frequency sensitivity. A fourth experiment, studying responses of humans to a similar regiment of 100 dB SPL tones, showed a relatively flat response curve unrelated to frequency sensitivity and more closely related to equal loudness contouring. Habituation of the unconditioned GSR in the human was more rapid than in the mouse, suggesting marked differences between the species in either the auditory systems and/or the mechanisms of auditory inhibition and GSR excitation.

The article reports on the etiology of auditory neuropathy spectrum disorder (ANSD). It is said that ANSD may be the diagnosis when two common hearing tests show divergent results. The patient has or had otoacoustic emissions in ANSD, however, the auditory brainstem response is abnormal or missing. The patient's pure-tone audiogram hearing test may range anywhere from essentially normal to a profound hearing loss. INSET: BY THE NUMBERS.