A review of the effects of ambient noise and reverberation on speech intelligibility in classrooms has been completed, initiated by the long-standing lack of agreement on permissible noise levels for good speech communication in educational facilities. Thus an overwhelming body of evidence has been collected to suggest that noise levels in particular are usually far in excess of any reasonable prescription aimed at producing optimal conditions for understanding speech in classrooms, assuming representative conditions of occupation by children. Quite surprisingly, poor classroom acoustics seem to be the prevailing condition for both normal-hearing and hearing-impaired students. In particular, reported ambient A-weighted noise levels are approximately 5--35 dB above values currently agreed upon for optimal understanding by normal-hearing children, and 17--32 dB too high for hearing-impaired children. Accordingly, strategies are discussed to decrease classroom noise levels and to improve classroom acoustics for speech communication purposes, taking into account the current state of economic constraints plaguing all school administrations.