The op/nions expressed are those of the ind/v/dua/ rev/ewers and are not necessar//y endorsed by the Editoria/ Board of this Journa/. , 1985. 256pp. Price $28.95. Those individuals who are familiar with the first edition of Yost andNielsen's excellent introductory textbook will be pleased to find that the second edition is a somewhat expanded and updated version of the already very popular text. Individuals not already familiar with the book will find it well worth investigating. The authors have produced a very readable, up-todate textbook which provides a clearly presented overview of research in hearing which is understandable by students with little previous exposure to either hearing or research. Since the intent is to provide a wide overview, the amount of time devoted to any single topic or to theoretical concepts is limited. A supplement is added at the end of each chapter providing those students wishing to pursue any topic in greater detail an indication of how to go about finding additional information on the topic. Additional readings can be provided by the instructor if he or she wishes to concentrate on any one area. One of the major advantages of the text is that the students like it and understand most of the material. I asked a class of Masters level Audi-GLENIS R. LONG
Previous studies have suggested that variations in the length of the hair cell cilia contribute to auditory nerve fiber tuning and tonotopic organization. In the granite spiny lizard, cilium length and the tonotopic organization of nerve fibers are correlated: fiber characteristic frequency increases as cilium length decreases. This results in an increasing fiber characteristic frequency in both the apical and basal direction. a pattern not previously seen in any vertebrate.
The effectiveness of electrical stimulation of the crossed olivocochlear bundle (COCB) was measured at different locations along the cochlear partition. Differential electrodes were used to sample the cochlear microphonic (CM) at turns I, II, and III. A pipette inserted into scala media in turns I, II, and III was used to measure the slow negative potential associated with electrical stimulation of the COCB. The responses of auditory nerve fibers were sampled within the modiolus and included a wide range of best frequencies. The magnitude of the slow negative potential was maximum in turn I and decreased in turns II and III. The increment in CM, produced by COCB stimulation, depended not only upon the location along the cochlear partition from which it was recorded, but also upon acoustic frequency. For low-frequency acoustic signals (below 700 Hz), the increment in CM was greatest at turn I and decreased toward the apex. At 5 kHz, COCB stimulation produced no detectable increment in CM at turn I. The reduction in discharges of auditory nerve fibers produced by COCB stimulation was greatest (16–20 dB in titration) when best frequency lay between 7 and 10 kHz. As best frequency decreased, the reduction in discharge rate with COCB stimulation decreased. Nerve fibers with very high best frequencies also showed minimal COCB effects. These data are discussed in relation to other recent information.
When the helicotrema was obstructed in guinea pigs, trapezoidal displacement of the round window membrane produced a trapezoidal microphonic which indicated a unidirectional displacement of the entire length of the basilar membrane. Responses of single auditory nerve fibers to the trapezoidal displacement of the round window membrane were recorded after obstruction of the helicotrema. About 39 % of the 424 fibers showed tonic responses which demonstrated directional sensitivity. More than 90 % of these fibers increased their discharge rate during displacement of the basilar membrane toward the scala tympani and decreased their discharge rate during oppositely directed displacement. Less than 5 % of the tonic fibers responded in the reverse manner. About 23 % of the auditory nerve fibers responded to onset and/or cessation of trapezoidal motion of the basilar membrane. About 28 showed a combination of the tonic and phasic responses. However it is probably that all phasic responses we observed do not arise from velocitysensitive fibers but some may represent artifacts. Both possibilities remain open until further studies are performed. The transduction mechanism of the cochlea is discussed on the basis of our data obtained by unidirectional displacement of the basilar membrane.
This paper is the first in a series of three concerning audiological tests and test batteries designed to differentiate cochlear from retrocochlear site-of-lesion. This paper concentrates on the techniques of clinical decision analysis with particular application to audiology. Those principles of clinical decision analysis which are most relevant for the audiologist are presented. Several techniques for measuring test performance are described and evaluated. In addition, this paper considers the problem of comparing test performance to determine the superior test.Traditionally, audiologists have used specialized tests to help determine the location of pathological conditions in the auditory system. When determining site-of-lesion, the audiologist has the responsibility to appropriately select, administer, and interpret these tests. Unfortunately, many audiologists do not have a coherent theoretical basis for dealing with the probabilistic nature of these tests, an accurate measure of the performance of these tests, or a logical and effective strategy for combining these tests into a test battery.Diagnostic tests are not unique to audiology; professionals in many health related areas face similar difficulties when using tests. Fortunately, effective techniques, called clinical decision analysis, do exist for evaluating the performance and utility of diagnostic tests. While many publications3.7.8-10. 12.17.18.20 have described clinical decision analysis and its application to medicine, there has been limited application to audi01ogy.l~ Only recently have more sophisticated techniques been applied to audiological tests.5.6. This paper is the first in a series of three concerning audiological tests and test batteries. The objective of this paper is to apply clinical decision analysis specifically to audiology so that the audiologist will have techniques for evaluating the performance of diagostic tests and for understanding the probabilistic uncertainties associated with these tests. The second paper evaluates audiological test performance based upon published clinical data.2' The third paper provides the audiologist with the conceptional framework for formulating and evaluating the audiological test battery.20 These three papers provide the essential information the audiologist needs to effectivly use audiological tests. CLINICAL DECISION ANALYSISClinical decision analysis (CDA) is a systematic approach to decision making under conditions of uncertainty.22 CDA is necessary because no audiological test is perfect and because certain "costs" are associated with clinical decisions. CDA permits us to make intelligent decisions by recognizing the probabilistic nature of tests and the consequences of error.To simplify our discussion of CDA we will make certain assumptions. First, we will consider only audiological tests which differentiate cochlear and retrocochlear lesions, and we restrict retrocochlear lesions to mean abnormalities of the cerebellopontine angle (CPA) including the VIIIth nerve. We assume that only two s...
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