How do people locate the source of a sound using both ears?

Humans locate the source of a sound in the horizontal plane through spatial localization, a process that relies on the brain comparing signals from both ears. Because the ears are separated, the brain detects minute differences in the sound's arrival time and intensity.12

The specific mechanism depends on the sound's frequency:

• Low-frequency sounds: The brain identifies the phase difference between the sound waves reaching each ear. Because these wavelengths are long, they diffract around the head, allowing the brain to perceive the timing offset.12
• High-frequency sounds: The head acts as a shield, creating a sound shadow that makes the sound louder in the ear closer to the source. In this case, the brain uses the difference in intensity (loudness) between the two ears to determine direction.12

These comparisons occur primarily at the brainstem and midbrain levels, specifically within the superior olivary complex, where neural pathways from both ears converge. While horizontal localization is highly effective, vertical localization is generally poor for most people, often requiring the interpretation of spectral shapes.21