“Making sense of sounds: patterns and noise” presented by Denham

Panel: NeuroArts-Noise

Tiny vibrations of the air molecules around us convey information about remote objects and their behaviour. What our ears receive is a mixture of the signals generated by whatever sound emitting sources happen to be present, which can of course change from one moment to the next. So, how do we make sense of the mixture and form mental images of the sound sources around us? I will argue that the auditory system constantly seeks out patterns in the incoming signals. These patterns range over many time scales, from the very rapid periodic vibrations perceived as pitch, to the sequences of sound events, perceived for example as a melody. Once a pattern has been detected, we can use it to decide which parts of the signal contributed to it and therefore belong together. Even more importantly, we can develop expectations of what should come next and when, and we can use mismatches between our expectations and what actually happens to refine our mental representations of things in the world. Since perceptual decisions are always made with incomplete information, the ability to construct alternative interpretations of the world and to flexibly switch between them is fundamental to natural perceptual systems. In this the role of intrinsic noise is crucial.