The second or foreign language listening curriculum cannot focus only on buying the right books and tapes. Skill building in listening comprehension is not something that can be accomplished in a half-hour lesson three times a week, nor can attention to listening be limited to language laboratory tapes. Listening, the language skill used most in life, needs to be a central focus—all day, every day—limited only by the availability of the target language in the school, the community, and the media.
Joan Morley
Aural Comprehension Instruction: Principles and Practices
[In Marianne Celce-Murcia, Ed., Teaching English as a Second or Foreign Language (3rd ed.).
Heinle & Heinle, 2001.]
The Essentials of Language Teaching 