The paper describes the use of an operant procedure to assess the speech perception of 11 young (7 to 35 months old) hearing impaired children and 11 normally hearing subjects. Subjects were presented with a repeating background stimulus and conditioned to turn their head on presentation of a contrasting syllable. The head-turning responses were reinforced with the activation of visual reinforcers (three lighted, moving mechanical toys). Stimuli were presented at either 25 or 100 dB depending on subject hearing status. Among findings were the following: both physiologic impairment and abundance of acoustic cuing affected speech sound discrimination; speech discrimination ability in hearing impaired infants may decline with age; and vowels were more easily differentiated than semivowels or consonants. The assessment method allows for clinical assessment of speech perception ability in infants for whom present, language-based, pediatric audiometric procedures are inappropriate. Attached material details the study methodology and findings. Includes 13 references. (DB)