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Historically, audiological procedures have focused on the assessment of the afferent (ascending) cochlear-VIIIth nerve system and have, for the most part, ignored the efferent (descending) auditory system. We report afferent and efferent auditory test results for two cases with a cholesterol cyst of the right petrous apex; one lesion involves the afferent segment of the auditory system, and the second lesion involves both the afferent and efferent segments of the auditory system. These “natural experiments” provide a unique opportunity to study the effect of a space-occupying lesion of the petrous apex on afferent and efferent function of the auditory system.

Neither auditory brainstem response (ABR) nor otoacoustic emissions (OAEs) are objective hearing tests, nor are their results always mutually consistent in any one patient. Therefore, it is quite possible for a patient to have normal emissions but absent or grossly abnormal ABR and behavioral audiograms that are inconsistent with either test. These patients, who may constitute as much as 10% of the diagnosed deaf population, are the subject of this article. To diagnose as many as possible properly from the onset, we urge triage (sorting or preselection by a system of priorities designed to maximize the effectiveness of treatment or outcome) using (1) tympanometry, (2) middle ear muscle reflexes, and (3) OAEs. Early diagnosis is essential because after either hearing aid use or the passage of time these patients often lose their OAEs and become almost indistinguishable from patients with ordinary deafness. Because auditory verbal therapy and hearing aids are rarely if ever successful with these patients until after cochlear implantation, it is essential to design intervention and interpret their audiograms physiologically rather than in conventional articulation index terms. This article offers management suggestions based on our experiences with close to 200 patients and their families. These suggestions include cued speech and baby signs for newborns. Cued speech gives them access to their parents' vocabulary and language, and the baby signs give them vocabulary to express needs and wants and remain linguistically attached. Then, if they are among the 93% of children who stay impaired, we have seen that cochlear implants are quite effective.

• 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)

We can now distinguish, in part, between nerve deafness and hair cell deafness through the use of otoacoustic emissions. We can also assess the efferent system by carefully quantifying the effects of contralateral stimulation on these same otoacoustic emissions. The suppression of transient evoked emissions by continuous contralateral white noise is an ostensibly small effect of 2 or 3 dB when studied over a 20-msec window. However, when subjected to microstructural analysis, the effect can exceed 6 to 8 dB in the zones from 10 to 20 msec after the stimulus has subsided. Temporal and spectral analyses reveal robust effects of contralateral lateral stimulation, although in any given normal subject it may be difficult to separate middle ear effects from efferent effects. Evidence is strong that the efferent effect is mediated in part by cholinergic — primarily nicotinic — receptors in the outer hair cell. However, a unique type of patient, who shows nearly normal pure-tone audiograms and absent ABRs, shows virtually no contralateral suppression of transient evoked emissions. Some other patients, with symptoms of Charcot-Marie-Tooth disease, may paradoxically show extremely poor audiograms, but perfectly normal evoked emissions along with absent contralateral suppression. The ABR, along with middle ear muscle reflexes and masking level differences, are all absent in these patients; we therefore think they have a disorder that desynchronizes most of their primary auditory nerve fibers and thereby disconnects them from any efferent activity or masking cancellation. The existence of such an auditory disorder, characterized by severe dysfunction in speech comprehension — especially when listening in noise—suggests that what appears to be a “central auditory imperception” might stem instead from a systemic peripheral primary neuropathy.

Cases are presented which show the clinical utility of recording an electrocochleographic response to bone‐conducted stimuli. The procedure is fraught with problems of acoustic control and artifact generation, but has distinct although limited value in clarifying masking dilemmas in patients with bilateral hearing loss.

• 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.

We can now distinguish, in part, between nerve deafness and hair cell deafness through the use of otoacoustic emissions. We can also assess the efferent system by carefully quantifying the effects of contralateral stimulation on these same otoacoustic emissions. The suppression of transient evoked emissions by continuous contralateral white noise is an ostensibly small effect of 2 or 3 dB when studied over a 20-msec window. However, when subjected to microstructural analysis, the effect can exceed 6 to 8 dB in the zones from 10 to 20 msec after the stimulus has subsided. Temporal and spectral analyses reveal robust effects of contralateral lateral stimulation, although in any given normal subject it may be difficult to separate middle ear effects from efferent effects. Evidence is strong that the efferent effect is mediated in part by cholinergic — primarily nicotinic — receptors in the outer hair cell. However, a unique type of patient, who shows nearly normal pure-tone audiograms and absent ABRs, shows virtually no contralateral suppression of transient evoked emissions. Some other patients, with symptoms of Charcot-Marie-Tooth disease, may paradoxically show extremely poor audiograms, but perfectly normal evoked emissions along with absent contralateral suppression. The ABR, along with middle ear muscle reflexes and masking level differences, are all absent in these patients; we therefore think they have a disorder that desynchronizes most of their primary auditory nerve fibers and thereby disconnects them from any efferent activity or masking cancellation. The existence of such an auditory disorder, characterized by severe dysfunction in speech comprehension — especially when listening in noise—suggests that what appears to be a “central auditory imperception” might stem instead from a systemic peripheral primary neuropathy.

Patients with auditory neuropathy show great difficulty hearing, especially in noise, and may produce audiograms that range from normal to what seems to be total deafness; however, virtually all patients described in the literature generate the following signs normal otoacoustic emissions; no efferent suppression of otoacoustic emissions with binaural, ipsilateral, or contralateral noise; absent auditory brainstem response (ABR) with no Wave I despite only modest pure tone audiometric loss; a long-ringing cochlear microphonic that extends into the 4 to 6 range, whether by ABR or transtympanic electrocochleography; no synchronous ABR wave forms with phase-inverting maximum length sequence techniques; absent middle ear muscle reflexes; absent masking level difference (release from masking in the presence of out of phase noise or signal); inordinately poor speech discrimination in the presence of noise compared with audiometric expectations; history of perinatal hyperbilirubinemia or blood dyscrasias in infants; and other systemic neuropathies in adults (eg, demyelinating diseases). This article summarizes both salient and recent literature and outlines current notions of patient treatment.

This report describes a case of traumatic sudden deafness in an adult and the unanticipated clinical problems in providing appropriate amplification and aural rehabilitation. The effect of acoustic distortion on central visual perceptual processes and previously ingrained aural language patterns is presented as a viable explanation. Implications regarding the necessity of evaluating the interaction between the auditory and visual channels are discussed.

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.

This practically oriented text was prepared by a well-known specialist in the field of industrial deafness, who designed his book to bring physicians and other students of hearing loss a useful guide to the intricasies of otologic examination, diagnosis, and hearing assessment. The 27 chapters discuss areas ranging from the classification of hearing losses with tuning forks, the inter-pretation of a pure-tone audiogram, various causes of conductive hearing and sensory-neural hearing losses, mixed central and functional hearing impairment, tinnitus and vertigo, techniques for hearing tests, and hearing loss in children. Since the book was not intended as a scholarly work on hearing, its simplicity and straightforward writing are both refreshing and appropriate; however, there are many inaccuracies or anachronisms included probably more because of expedience than ignorance on the part of this experienced author.For example, the author continues to recommend mastoid placement in bone conduction testing, makeshift masking without

This book has much to recommend it for the otolaryngologist, the pediatrician, gerontologist, beginning audiologist, rehabilitation specialist, and educator. Although marred by many typographical and bibliographic citation errors, there are sections of this book that may become important milestones in audiologic literature; these include the chapter by Studebaker and Brandy on industrial and military audiology and the truly exceptional chapter, "Psychological and Psychiatric Aspects of Profound Hearing Loss," by Vernon and Mindel.Also worthy of special note are the chapters on hearing aids, electroencephalic audiometry, differential audiology, pure-tone audiometry, speech audiometry, and otologic assessment and treatment. However, middle ear impedance and tympanometry were not discussed, a serious omission for audiologists and otolaryngologists.Otolaryngologists should particularly appreciate the section on hearing aids and their selection, and on the industrial and military aspects of audiology. By contrast, the anatomy and physiology of the auditory system is covered far better in many other

Educational objectives: To use and interpret a battery of new and powerful auditory electrophysiologic tests.

Ten patients presented as children or young adults with hearning impairments that, by behavioural and physiological testing, were compatible with a disorder of the auditory portion of the VIII cranial nerve. Evidence of normal cochlear outer hair cell function was provided by preservation of otoacoustic emissions and cochlear microphonics in all of the patients. Auditory brainstem potentials showed evidence of abnormal auditory pathway function beginning with the VIII nerve: the potentials were absent in nine patients and severely distorted in one patient. Auditory brainstem reflexes (middle ear muscles: crossed suppression of otoacoustic emissions) were absent in all of the tested patients. Behavioural audiometric testing showed a mild to moderate elevation of pure tone threshold in nine patients. The extent of the hearing loss, if due to cochlear receptor damage, should not have resulted in the loss of auditory brainatem potentials. The shape of the pure tone loss varied, being predominantly low frequency in five patients, flat across all frequencies in three patients and predominantly high frequency in two patients. Speech intelligibility was tested in eight patients, and in six was affected out of proportion to what would have been expected if the pure tone loss were of cochlear origin. The patients were otherwise neurologically normal when the hearing impairment was first manifest. subsequently, eight of these patients developed evidence for a peripheral neuropathy. The neuropathy was hereditary in three and sporadic in five. We suggest that this type of hearing impairment is due to a disorder of auditory nerve function and may have, as one of its causes, a neuropathy of the auditory nerve, occurring either in isolation or as part of a generalized neuropathic process.

Educational objectives: To use and interpret a battery of new and powerful auditory electrophysiologic tests.