Bottom-up and top-down processing of listening skills

Listening is an active process for constructing meaning in which two kinds of processes are
involved simultaneously: bottom-up and top-down processing. Richards (1990) explains these two as follows:
A. Bottom-up processing
Bottom-up processing … refers to the use of incoming data as a source of information about the meaning of a message. From this perspective, the process of comprehension begins with the message received, which is analyzed at successive levels of organization sounds, words,clauses, and sentences until the intended meaning is arrived at. Comprehension is, thus,viewed as a process of decoding. (p. 50)
B. Top-down processing
Top-down processing refers to the use of background knowledge in understanding the
meaning of a message. Background knowledge may take several forms. It may be previous
knowledge about the topic discourse, it may be situational or contextual knowledge, or it maybe knowledge stored in long-term memory in the form of schemata and script plans about the overall structure of events and the relationships between them. (p. 51)