cues are collectively known as the sense of hearing and are the subject of research within the fields of psychology, cognitive science, and neurobiology. Auditory system The auditory system of humans and animals allows individuals to assimilate information from the surroundings, represented as sound waves. Sound waves first pass through the pinnae and the auditory canal, the parts of the ear that comprise the outer ear. Sound then reaches the tympanic membrane in the middle ear (also known as the eardrum). The tympanic membrane sets the malleus, incus, and stapes into vibration. The stapes transmits these vibrations to the inner ear by pushing on the membrane covering the oval window, which separates the middle and inner ear. The inner ear contains the cochlea, the liquid-filled structure containing the hair cells. These cells serve to transform the incoming vibration to electrical signals, which can then be transmitted to the brain. The auditory nerve carries the signal generated by the hair cells away from the inner ear and towards the auditory receiving area in the cortex. The signal then travels through fibers to several subcortical structures and on to the primary auditory receiving area in the temporal lobe. Cues for locating sound Humans use several cues to determine the location of a given stimuli, mainly by using the timing difference between ears. These cues allow individuals to identify both the elevation, the height of the stimuli relative to the individual, and the azimuth, or the angle of the sound relative to the direction the individual is facing. Interaural time and level difference Unless a sound is directly in front of or behind the individual, the sound stimuli will have a slightly different distance to travel to reach each ear. This difference in distance causes a slight delay in the time the signal is perceived by each ear. The magnitude of the interaural time difference is greater the more the signal comes from the side of the head. Thus, this time delay allows humans to accurately predict the location of incoming sound cues. Interaural level difference is caused by the difference in sound pressure level reaching the two ears. This is because the head blocks the sound waves for the further ear, causing less intense sound to reach it. This level difference between the two ears allows humans to accurately predict the azimuth of an auditory signal. This effect only occurs for sounds