Hearing
Not everyone hears with ears: crickets have a hearing membrane on their front legs, mosquitoes locate sound with a special organ on their antennae, and toothed whales hear with their lower jaw. But humans have ears.
Admittedly, most signals reach us through our eyes. But we can't have them everywhere. Our ears, on the other hand, cover the entire space and reliably inform us of which side danger is coming from; the difference between right and left can be a matter of fractions of a millisecond!
Much of this analysis begins in stations of the Auditory pathway that lie far ahead of the conscious Auditory cortex Other information also flows into the processing at an early stage, until the auditory Cortex sorts and evaluates the sound information. In this way, the brain constructs the complex perceptual world of hearing from the mechanical stimulus of a sound wave. It analyzes where a sound source is located and whether it is a human voice, delicate violin tones, or the roar of nearby traffic. And it links what it hears with experience, emotions, and all other sensory impressions. This is an amazing feat – right between our ears.
▸ Hearing – more than just Sound and Vibration
Auditory pathway
The auditory pathway refers to the nerve fibers that transmit acoustic information from the inner ear to the primary auditory cortex. In humans, the auditory pathway consists of five switching points: the spiral ganglion, the auditory nuclei in the brainstem, the inferior colliculus, the medial geniculate body of the thalamus, and the primary auditory cortex.
Auditory cortex
The auditory cortex is a part of the temporal lobe that is involved in processing acoustic signals. It is divided into the primary and secondary auditory cortex.
Cortex
cortex cerebri
Cortex refers to a collection of neurons, typically in the form of a thin surface. However, it usually refers to the cerebral cortex, the outermost layer of the cerebrum. It is 2.5 mm to 5 mm thick and rich in nerve cells. The cerebral cortex is heavily folded, comparable to a handkerchief in a cup. This creates numerous convolutions (gyri), fissures (fissurae), and sulci. Unfolded, the surface area of the cortex is approximately 1,800cm².
