Otitis media affects nearly every child at some time; many children have mild-to-moderate hearing losses for prolonged periods. The effects of these losses on language and educational development may be significant; possible mechanisms are discussed. Especially in suboptimal listening situations, speech perception may be impaired by even a mild hearing loss. Patterns of imperception are predicted by comparison of composite audiometric data from children with middle ear effusions with speech power data, and by analysis of sound pressure waveforms of speech filtered to simulate the typical hearing loss of these patients. A new method of analysis of brain stem evoked responses, yielding response components attributable to binaural interaction, is reported. This and other evoked response techniques may be able to identify objective changes in auditory nervous system function attributable to relative sensory deprivation during development. Finally, directions for further research in this area are discussed.