The coding of complex sounds in the early auditory system has a 'standard model' based on the known physiology of the cochlea and main brainstem pathways. This model accounts for a wide range of perceptual capabilities. It is generally accepted that high cortical areas encode abstract qualities such as spatial location or speech sound identity. Between the early and late auditory system, the role of primary auditory cortex (A1) is still debated. A1 is clearly much more than a 'whiteboard' of acoustic information-neurons in A1 have complex response properties, showing sensitivity to both low-level and high-level features of sounds.