This award is under the Long and Medium-Term Research at Foreign Centers of Excellence Program, which enables U.S. scientists and engineers to conduct three to twelve months of research abroad at research centers of proven excellence. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twelve-month postdoctoral research visit by Dr. Cornelia W. Fales to the Institut de Recherche et Coordination to work with Dr. Stephen McAdams. The purpose of this study is to explore the relationship of noise and inharmonicity as timbral components. By noise in this context, Dr. Fales means the presence of random frequencies at sufficient energy to make a perceptual difference in the timbral quality of the tone they surround. Specifically, the project will have two parts, both of which will test the ability of noise to disguise inharmonic partials of a complex tone. A third study is included to be undertaken if time and resources allow, which tests the potential of noise to induce perceptions desired by a performer. Auditory processing has been described as occurring in two directions at once: from the bottom up, which is called primitive processing, and from the top down, which is called schema-based processing. If the cognitive heuristics which regulate primitive processing of sound are truly innate then it is in the activity of schema-based processing that evidence may be found for the variety of the world's music and musical behavior. It is here that we may find evidence in support of the contention that timbral sensitivity varies with a listener's use of timbre - in music or in speech. The acoustic circumstances under which a tone will fuse with the noisy components that are part of, or close to its source, the point at which a tone immersed in noise becomes only a series of frequencies contributing to the noise and tone - these are questions which bear on the subject of instrumental timbre. These questions are equally valid for the study of instrumental music in western culture. The line between noise and tone is often contextually established: is the high-frequency hum of the dentist's drill noise or tone? are instrumental ideophones noisy or tonal? As studies of the continuity illusion have shown, the very perception of noise is often dependent on its acoustic context; listeners have demonstrated the ability to hear unbroken speech and nonspeech sounds right through an interfering gap of noise which does indeed break the sequence of sounds that surround it. While psychoacousticians have developed precise definitions to distinguish noise from tone, the perceiver's categories are less clearly defined. The results of this project will bear on all these issues.
