It is hypothesized that higher auditory cortical functions include the two coding system —phonemic and musical— proposed by Luria, and a third coding system that serves for cognition of environmental sounds and auditory space. The purpose of the present paper is to report a test for the third coding system devised in our laboratory, and its application to a developmental study on space cognition in children. The test material was a series of sounds, which were stereophonically recorded by a tape recorder (SONY TC-3000 SD) by the side of a rail road crossing, including noises of automobiles and a motorcycle rolling over the rail road crossing, sounds of the crossing signals, and children's shouts.
    The subjects were sixty normal pupils ranging from six to twelve years old and sixteen healthy adults with normal hearing. They were asked to identify the sounds presented binaurally through headphones (Aurex HR-XI) from the same tape recorder used for the recording, and to reconstruct the space where the recording was made.
    The results obtained were as follows: (1) The identification of the sounds depended on their familiarity as well as on the intensity and duration of the sounds. (2) A statistically significant difference of development of auditory space cognition was found between the group under nine years and the group above ten years of age. This finding supports Piaget's theory on the development of cognition of space in children.