An impressive aspect of the human brain is its ability to process the thousands of different combinations of phonemes that are used in the sentences of everyday speech. Although verbal speech is unique to humans, the initial neural processing of communication sounds by the cortex is likely to be similar in other mammalian species. In the guinea pig cortex there are at least 7 auditory areas: two core areas, the primary area AI and a dorsocaudal area (DC) which are almost entirely surrounded by 5 belt areas. We presented a digitised example of a guinea pig vocalization called chutter to animals while recording with glass insulated tungsten electrodes from cortical units in 4 areas. Guinea pigs were terminally anaesthetised with a mixture of ketamine and xylazine and the cortex was exposed as described in Wallace et al. (2002) Hearing Research 172:160-171. Stimuli were presented binaurally in the closed field. Peri stimulus time histograms were constructed from the responses to the chutter presented at a level equivalent to 20 dB above the pure tone threshold. The chutter used has a series of irregular noisy bursts of sound of different duration and loudness. When the responses to this call were compared across all 412 units, specific responses were found at 17 temporal positions. We then classified our units in terms of whether they responded or not within windows set to correspond to each of these 17 temporal components. No one unit responded during all of the windows, but each had a distinct combination of responses at as many as 9 different windows. Within each area there was a wide range of different response combinations. In AI there were 65 different combinations of response amongst 260 units while in DC there were 31 distinct combinations among 62 units (14 of these combinations were not found in AI). In the ventrorostral belt (VRB, 75 units) there were 38 distinct response combinations (18 of these were not found in AI or DC) and in the dorsocaudal belt (DCB) all 15 units responded differently: 2 of them in a way unique to DCB. Thus out of 412 recorded units there were 99 (24%) distinct temporal response patterns to the chutter. This is a remarkably low rate of redundancy within the cortex and implies that the cortex is sensitive to the sequence of salient sound features in the environment. To further illustrate the differences between cortical areas the mean response was plotted for each area. Mean responses were very similar in AI and DC with large responses at several temporal windows, but very different in DCB which gave its largest response at a different window. The mean response in VRB was smaller than the core areas except for the second last window.