In this paper, electroencephalography (EEG) measurements are used to assess cortical functional connectivity in response to perceived audio quality. Specifically, in the conducted experiment the brainwave response patterns of human subjects are directly recorded using a high resolution EEG while they listen to audio whose quality varies with time. A new causal bi-directional information (CBI) measure is proposed which quantifies the information flow between EEG electrodes by appropriately grouping them into specific regions of interest (ROIs) over the cortex. It is shown that CBI can be intuitively interpreted as a causal bi-directional modification of directed information applied to a generalized cortical network setting, and inherently calculates the divergence of the observed data from a multiple access channel with feedback. The proposed measure is used to analyze and compare the information flow between ROI pairs for the case when the subject listens to high quality audio compared to when the subject listens to low quality audio. The results indicate that CBI is a more robust measure for inferring connectivity when compared to using standard directed information measures.