The light microscopic findings in several recently acquired human temporal bones have prompted me to restudy the problem of deafness from aging and to formulate a new classification for presbycusis. The evidence suggests that there are four pathological types. Although more detailed anatomical and clinical studies are needed to support the concepts to be presented, they do provide an improved basis for understanding the clinical manifestations of deafness of aging and suggest avenues for further study of this important problem. The underlying pathological mechanisms in the aging ear are much more complex than previously conceived and it is safe to predict that our present ideas certainly will be amended as new evidence is accumulated.
I now believe that, in addition to the sensory and the neural kinds of presbycusis which have been described previously,1,2 there are also metabolic and mechanical types. It is not surprising that more than one