What is the difference between top-down and bottom-up processing in relation to the auditory system?
As the metaphor implies, the difference between top-down and bottom up processing has to do with direction. In the top down direction, processing begins with higher order (top level) information. That is, information higher up in the system is used to process information lower in the system. The converse is the case for bottom-up processing. In that case, the processing begins lower in the system, closer to the periphery and becomes interpreted as it is passed up to higher order levels. This directional metaphor has been used when representing different kinds of processing: cognitive; language, phonological, neurological, and auditory.
Early in the 1980s, when this information processing metaphor was the talk of the town, the debates were between language people, like me, and audiology people like Jack Katz. As you might have guessed, I focused on how language influenced perception, a top down approach, and Jack Katz' emphasis was on what happened to the signal as it became interpreted. We wrote an article together, trying to resolve our differences, and concluded that processing goes in both directions simultaneously and is likely to differ depending upon the task at hand. This got us only so far, however. We still differed when it came to deciding what to work on first when meeting up with a client who had processing difficulties. I felt that one had to work on the higher levels first to aid the person in lower order processing, e.g., teaching phonemes in meaningful units before requiring the person to work on auditory discrimination. Working on language before working on such abstract things as sounds. Jack Katz was more likely to begin work closer to the signal. We remained friends, even though each saw the other's therapy approaches as flawed.
Judy Duchan is a speech-language pathologist whose specialty is children's language development and children's and adult's language disabilities. Her current work is on the history of speech pathology in America and the UK and on inclusionary practices. She lives in Buffalo, New York and now that she has retired spends lots of time in London, England and Sydney, Australia. Wherever she is, she can be reached at firstname.lastname@example.org