The auditory system underlies the ability to perceive and respond to sound in the environment. However, perception and behavioral responses to sound are not static, but change over time depending on one's sensory context and internal state. The neural mechanisms underlying this flexibility are not yet well-understood. In this dissertation, we build on this work by studying how two aspects of behavioral state, arousal and task engagement, co-modulate the activity of many neurons simultaneously in auditory cortex.