Attention is essential for navigating complex acoustic scenes, when the listener seeks to extract a foreground source while suppressing background acoustic clutter. We explored the neural correlates of this perceptual ability by measuring rapid changes of spectrotemporal receptive fields (STRFs) in primary auditory cortex during detection of a target tone embedded in noise. We observe diverse adaptive patterns in the gain and shape of primary auditory cortical receptive fields. The net effect of these adaptations was to accentuate the representation of the target tone relative to the noise, by enhancing responses of near-target cells to the tone during high-SNR tasks, while suppressing responses of far-from-target cells to the masking noise in low-SNR tasks. These adaptive STRF changes were largest in high-performance sessions, confirming a close correlation with behavior