ABSTRACT
Speech understanding and reading are compared and contrasted. Each is presented as a multifaceted activity in which both bottom-up, analytic, data-driven processes and top-down, inferential, knowledge-driven processes play important roles. Differences between speech understanding and reading are apparent when one focuses on stimuli and the sensory systems that transduce them, but become
INTRODUCTION
Speech understanding and reading are among the most complex perceptualcognitive skills that human beings have developed. In some respects these skills are quite different. Speech understanding is universal among people everywhere barring physical or mental disabilities that interfere with its normal development. Reading ability is far from universal and, even among individuals in literate countries, is often poorly developed. Speech understanding is acquired spontaneously, and it would seem effortlessly, during the first few years of life. Reading ability typically is acquired after oral-aural language skills have been fairly well developed, and then only as a result of some considerable deliberate effort. To make this point another way: Speech skills are learned in the absence of any explicit attempts to teach them; if reading skills are not taught, they are not, as a rule, acquired at all.
