To explore the effects of acoustic and behavioral context on neuronal responses in the core of auditory cortex (fields A1 and R), two monkeys were trained on a go/no-go discrimination task in which they learned to respond selectively to a four-note target (S+) melody and withhold response to a variety of other non-target (S-) sounds. We analyzed evoked activity from 683 units in A1/R of the trained monkeys during task performance and from 125 units in A1/R of two naive monkeys. We characterized two broad classes of neural activity that were modulated by task-performance. Class-I consisted of tone-sequence-sensitive enhancement and suppression responses. Enhanced or suppressed responses to specific tonal components of the S+ melody were frequently observed in trained monkeys, but enhanced responses were rarely seen in naive monkeys. Both facilitatory and suppressive responses in the trained monkeys showed a different temporal pattern from that observed in naive monkeys. Class-II consisted of non-acoustic activity, characterized by a task-related component that correlated with bar-release, the behavioral response leading to reward. We observed a significantly higher percentage of both Class-I and Class-II neurons in field R than in A1. Class-I responses may help encode a long-term representation of the behaviorally salient target melody. Class-II activity may reflect a variety of non-acoustic influences, such as attention, reward expectancy, somatosensory inputs, and/or motor set and may help link auditory perception and behavioral response. Both types of neuronal activity are likely to contribute to the performance of the auditory task.