The auditory system of primates includes a complex network of subcortical nuclei and cortical areas. In monkeys, the ventral nucleus of the medial geniculate complex projects to three primary-like auditory areas (AI, R, and RT), forming the first stage of cortical processing. These areas interconnect and project to homotopic and other locations in the opposite hemisphere, as well as to eight belt areas, forming the second stage. The belt areas project to a lateral parabelt region, which is divided into rostral and caudal subdivisions, forming the third stage. These regions connect to adjoining auditory and multimodal areas in the temporal lobe and to four functionally distinct regions in the frontal lobe. Histochemical studies show that chimpanzees and humans have an auditory core similar to that of monkeys. The challenge for future research is to understand how this complex system processes and utilizes auditory information. The auditory system of mammals includes many interconnected nuclei and cortical areas. Understanding how this system processes and uses auditory information is a challenge due to variability in cortical organization across species. Studies of the auditory system of primates are important because primates vary in size, auditory behavior, and brain complexity. The auditory cortex of primates has a core area with three primary-like fields (AI, R, and RT), surrounded by a belt of secondary fields and a lateral parabelt. The core areas have primary-like features, including responses to pure tones, dense thalamic inputs, and architectonic characteristics. The core areas are interconnected and project to belt areas, which are a second stage of processing. The belt is an obligatory second stage, with limited connections to more distant fields. The parabelt is a third stage, with connections to the frontal lobe and other regions. The parabelt may have functionally distinct subdivisions, but little is known about how to divide it. In humans, evidence suggests a hierarchical processing model in the auditory cortex, with distinct fields that can be dissociated using various techniques. Functional studies in humans indicate the presence of multiple hierarchically arranged fields, consistent with the primate model. The auditory cortex of monkeys includes at least 20 interconnected areas or multimodal regions, with at least four distinct levels of processing. Information is widely distributed within levels, between areas of the same level in opposite hemispheres, and between levels. The existence of multiple areas at even the primary level of processing suggests overlapping functions and the potential for compensation in case of lesions. The highly serial nature of processing from level to level indicates that extensive damage to any level would be devastating. The study of the auditory cortex in primates provides insights into the nature of processing within the network.The auditory system of primates includes a complex network of subcortical nuclei and cortical areas. In monkeys, the ventral nucleus of the medial geniculate complex projects to three primary-like auditory areas (AI, R, and RT), forming the first stage of cortical processing. These areas interconnect and project to homotopic and other locations in the opposite hemisphere, as well as to eight belt areas, forming the second stage. The belt areas project to a lateral parabelt region, which is divided into rostral and caudal subdivisions, forming the third stage. These regions connect to adjoining auditory and multimodal areas in the temporal lobe and to four functionally distinct regions in the frontal lobe. Histochemical studies show that chimpanzees and humans have an auditory core similar to that of monkeys. The challenge for future research is to understand how this complex system processes and utilizes auditory information. The auditory system of mammals includes many interconnected nuclei and cortical areas. Understanding how this system processes and uses auditory information is a challenge due to variability in cortical organization across species. Studies of the auditory system of primates are important because primates vary in size, auditory behavior, and brain complexity. The auditory cortex of primates has a core area with three primary-like fields (AI, R, and RT), surrounded by a belt of secondary fields and a lateral parabelt. The core areas have primary-like features, including responses to pure tones, dense thalamic inputs, and architectonic characteristics. The core areas are interconnected and project to belt areas, which are a second stage of processing. The belt is an obligatory second stage, with limited connections to more distant fields. The parabelt is a third stage, with connections to the frontal lobe and other regions. The parabelt may have functionally distinct subdivisions, but little is known about how to divide it. In humans, evidence suggests a hierarchical processing model in the auditory cortex, with distinct fields that can be dissociated using various techniques. Functional studies in humans indicate the presence of multiple hierarchically arranged fields, consistent with the primate model. The auditory cortex of monkeys includes at least 20 interconnected areas or multimodal regions, with at least four distinct levels of processing. Information is widely distributed within levels, between areas of the same level in opposite hemispheres, and between levels. The existence of multiple areas at even the primary level of processing suggests overlapping functions and the potential for compensation in case of lesions. The highly serial nature of processing from level to level indicates that extensive damage to any level would be devastating. The study of the auditory cortex in primates provides insights into the nature of processing within the network.