Representative papers

Auditory perception of space

Integration of sound localization cues

S. Furukawa (2008) "Detection of combined changes in interaural time and intensity differences: Segregated mechanisms in cue type and in operating frequency range?," J. Acoust. Soc. 123, 1602-1617.

The auditory system integrates information about interaural intensity and time difference (IID and ITD) to judge sound-source direction on the left-right dimension. This paper suggests a possibility that the integration mechanism differs between frequency ranges.

Neural representation of the auditory space

S. Furukawa, L. Xu, J.C. Middlebrooks (2000). "Coding of sound-source location by ensembles of cortical neurons," J. Neurosci. 20, 1216-1228.
S. Furukawa, J. C. Middlebrooks (2002). "Cortical representation of auditory space: Information-bearing features of spike patterns," J. Neurophysiol. 87, 1749-1762.

These papers indicate that the sound source location is represented in the auditory cortex by firing patterns of neural ensembles.

Perceptual sound source segregation

S. Furukawa, and B.C.J. Moore (1996). "Across-channel processes in frequency modulation detection," J. Acoust. Soc. Am. 100, 2299-2311.

The energy from one sound source often distribute across frequency bands. How does the auditory system group together the frequency componets that belong to one source? It may be that the coherence of the pattern of frequency change (frequency modulation; FM) is a cue for the grouping. This paper indicates that the auditory system includes a mechanism that is sensitive to the FM coherence.

S. Furukawa, J.C. Middlebrooks (2001). "Sensitivity of auditory cortical neurons to locations of signals and competing noise sources," J. Neurophysiol. 86, 226-240.

When there are two sound sources ("signal" and "noise"), the signal becames more audible with increasing spatial separation of the two sources ("spatial unmasking"). We found that a neural paralell of the spatial unmasking in the auditory cortex.

Plasticity of the auditory system

S. Furukawa, K. Maki, M. Kashino, H. Riquimaroux (2005). "Dependency of the interaural phase difference sensitivities of inferior collicular neurons on a preceding tone and its implications in neural population coding," J. Neurophysiol. 93, 3313-3326.

The perceived location of a sound shifts depending on the location of a preceding sound, in such a manner that would emphasize the perceived difference between the sounds ("auditory localization aftereffect"). We found a similar phenomon in the responses of neurons in the inferior colliculus, a brainstem nucleus.