IBN: 9634361 PI: Baras Timbre is the percept that allows one to distinguish between musical instruments playing the same note, or between different vowels spoken in the same voice pitch. Only complex sounds composed of many tones have distinct timbres or sound qualities. The most important physical correlate of this percept is the distribution of energy in these tones. This energy profile resembles intuitively the distribution of light in an image. The question addressed in this research is how the acoustic profile (or image) is extracted in the auditory system and how is it represented in the brain. Specifically, we seek to clarify what features of this acoustic image are important in forming the timbre of the sound, and which features are redundant and can be ignored.The results obtained from such a study can potentially lead to a better understanding of how speech and musical sounds are preceived. This in turn has immediate applications in the development of effective automatic speech recognition systems, in speech and music synthesis, in robust communication channels, and in prosthetic devices for the deaf.