In developing a theoretical framework for the field of ecological acoustics, Gaver (1993b) distinguished between the experience of musical listening (perceiving sounds) and everyday listening (perceiving sources of sounds). Within the everyday listening experience, Gaver (1993a) proposed that the frequency of an object results from, and therefore specifies, the size of that object. The relation in which frequency and object size stand to one another is an example of a nomic mapping. A symbolic mapping involves the pairing of unrelated dimensions and, relative to a nomic mapping, requires an additional step in recognition and learning. Using a perceptual identification task, an experiment investigated the hypothesis that nomic mappings are identified more easily than symbolic mappings. It was predicted that the advantage manifests only during the everyday listening experience, and that the initially superior recognition of nomic mappings is equaled by symbolic mappings after extended exposure. The results provided support for the hypotheses. Theoretical implications of the differential recognition of nomic and symbolic mappings are discussed, together with practical applications of nomic relations.While speech and music perception have received considerable attention in experimental psychology (Deutsch, 1999;Jusczyk, 1997), relatively little is known about the way in which humans perceive other environmental sounds. Recent research in ecological acoustics has focused on the way in which a sound may contain meaningful information for the listener (e.g