Final answer:
The ability to locate sounds involves the interaction of monaural cues from each ear's pinna and binaural cues that detect differences in sound wave arrival times and intensities between the two ears.
Step-by-step explanation:
We can locate sounds in our environment using both monaural and binaural cues. Monaural cues allow us to identify sounds that occur above, below, in front, or behind us by the way each ear's pinna interacts with sound waves. For sounds not directly in front or behind, our brain relies on binaural cues, involving the interaural time difference and interaural level difference. A sound originating off to one side will reach the closer ear slightly faster and with a stronger level than the farther ear, due to the sound wave's attenuation as it travels through the head. Our auditory brain stem processes these differences to localize sound sources in our environment.