Interaural Time Difference (ITD) refers to the small difference in the time it takes for a sound to reach each ear. When a sound originates from one side, it reaches the ear closer to the source slightly earlier than the other ear. This time difference helps the brain determine the direction of the sound. The brain processes these timing cues to localize sounds in the environment. ITD is particularly effective for low-frequency sounds, allowing humans and many animals to accurately perceive where sounds are coming from, which is essential for communication and survival.