Josh McDermott's MIT course 9.35, Perception, turns to hearing in this lecture, examining how the ear and brain work out where a sound comes from. He covers interaural time and level differences as cues for localization, the limits those cues run into (such as front-back confusion and the cone of confusion), and how head movement and pinna shape help resolve ambiguity. The lecture then moves through the perceptual dimensions of sound itself: pitch as a percept tied to periodicity, timbre as the harder-to-define quality that lets listeners distinguish instruments playing the same note, and loudness as a function of both amplitude and frequency. McDermott closes with psychophysical methods, the experimental techniques researchers use to measure these subjective percepts systematically, connecting the auditory content back to the course's broader methodological toolkit for studying perception.