Understanding the neural mechanisms governing different states of cortical processing is pivotal for unraveling the cognitive processes underpinning perception. Observing freely-behaving animals offers a naturalistic environment that elicits a manifold of dynamically changing cognitive and behavioral states, and thus reflects real-world scenarios more accurately than under anesthesia or head-fixed conditions. In this study, we explore the interplay between evoked and spontaneous population activity and its impact on auditory processing within the primary auditory cortex of freely-moving gerbils, voluntarily engaged or dis-engaged in auditory-based behavioral tasks.Leveraging multi-electrode array recordings, we discerned distinct neural population activity patterns that delineate various internal auditory brain states. Specifically, periods characterized by diminished spontaneous activity relative to evoked responses coincided with states of behavioral engagement and focus on auditory stimuli, while heightened spontaneous activity correlated with task-irrelevant behaviors. Voluntarily-induced engaged state yielded an increased signal-to-noise ratio of auditory cortical unit encoding, suggesting a mechanism for attentional enhancement of auditory processing. Remarkably however, we observed animals exhibiting an engaged brain state even in the absence of auditory stimulation, suggesting that the observed neural processing pattern represents a cognitive and not necessarily a specific behavioral state of the animal. These findings underscore the predictive value of the relationship between evoked and spontaneous population activity in discerning dynamic internal states.In summary, unraveling this dynamic relationship between cortical and voluntary behavioral states enriches our comprehension of auditory attention mechanisms and the intricate interconnection between cognition and active behavior.