Temporal Windows of Integration in Human Auditory Cortex

Abstract: Acoustic signals, such as speech and music, evolve over time, carrying information at multiple temporal scales. For example, phonemes and syllables have average lengths of 10s or 100s of milliseconds, respectively, while sentences and melodies typically span several seconds. An active area of research in human auditory neuroscience investigates how these temporal scales, and their associated modulation rates, are represented in the auditory system. I will present three studies that have used fMRI to address this question with increasingly complex signals, ranging from simple sinusoidally amplitude modulated noise-band carriers via complex forms of spectrotemporal amplitude modulation to natural speech signals. The results reveal a pronounced sensitivity to slow temporal modulations (i.e. longer temporal scales) at the level of human auditory cortex, superimposed on which is a hierarchical organisation with respect to sound complexity: increasingly complex signals recruit areas further down the processing hierarchy in auditory association cortex.

Dr. Tobias Overath is a Postdoctoral fellow at the University College London, United Kingdom.