Nelson Yuan-sheng Kiang
MIT, Harvard Medical School, Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA 02114
, and Massachusetts General Hospital
Harvey Fletcher was an original thinker whose career is worth examining for future scientists. Trained as a physicist, he developed a pragmatic approach to psychophysics that virtually defined the engineering approach to acoustic communication. Although his practical achievements were considerable, he also tried to integrate all that was known about hearing in the 1953 version of his ``space-time pattern theory of hearing.'' It is instructive to compare that formulation with the ideas of today after more than four decades of intense research. Many of the issues that concerned Fletcher have been resolved; many others remain uncertain. For example, the observation that low-frequency stimuli can mask high-frequency stimuli whereas high-frequency stimuli cannot mask low-frequency stimuli was accorded great significance by Fletcher. It is now known that a key factor lies in the asymmetry of tuning curves for basal and apical turn auditory-nerve fibers. On the other hand, the full implications of these phenomena, especially for central processing mechanisms, is virtually unexplored. What is clear is that a major effort to produce a unified theoretical framework for research in hearing is long overdue and a modern Fletcher would be welcome today.