Auditory Cortex

What is the auditory cortex?

The auditory cortex is a set of brain regions that process sound. Primary auditory cortex lies in the temporal lobe and receives information already processed through several stages below the cortex.

Auditory cortex location and organization

Purves and colleagues’ neuroscience textbook describes its tonotopic organization: nearby regions tend to respond to nearby sound frequencies. Other auditory cortical areas surround the primary region and respond in more complex ways.

From the ear to the cortex

Sound vibrates structures in the cochlea, where hair cells convert mechanical movement into electrical signals. The auditory nerve carries information to the cochlear nuclei in the brainstem. Several pathways then process it through brainstem and midbrain stations, including the inferior colliculus, before the medial geniculate region of the thalamus sends input to auditory cortex. This is a network of processing stages, not a direct wire from ear to cortex.

The textbook’s auditory-system summary explains how features of sound are processed along this route.

Hearing speech and music

Recognizing speech, locating a sound, and following music involve more than one processing stage. Some operations take place below the cortex, while others involve several cortical areas. The auditory cortex contributes to the experience, but it is not a single place where sound arrives unprocessed and acquires all its meaning.

Consider three everyday tasks.

• Distinguishing spoken syllables requires sensitivity to the sequence and timing of sounds.
• Following a melody involves hearing changes in pitch and their order.
• Locating a ringing phone uses differences between the signals reaching the two ears; comparisons already begin in brainstem circuits, with later processing contributing to sound location.

Auditory cortex contributes to these tasks together with the earlier stages and other cortical regions.