From Ear to Thalamus

Interaural Time Difference (ITD)

The difference in time it takes for a sound to reach each ear, used to localize sound.

Interaural Level Difference (ILD)

The difference in sound pressure level reaching each ear, used to localize sound, especially at higher frequencies.

Head-Related Transfer Function (HRTF)

A spectral cue that describes how the body affects sound before it reaches the inner ear, used for localization.

Sound Pressure Level (SPL)

A measure of the magnitude of pressure fluctuations in sound, with 0 dB SPL indicating the threshold of hearing.

Frequency

How rapidly pressure fluctuates in sound, measured in Hertz (Hz); human hearing ranges from 20 Hz to 20,000 Hz.

Cochlea

The inner ear structure that acts as a frequency analyzer and contains fluids that process sound.

Basilar Membrane

A membrane in the cochlea that moves in response to sound, with different parts responding to different frequencies.

Stereocilia

Hair-like projections on hair cells in the cochlea that deflect in response to sound and convert mechanical signals to neural signals.

Phase-Locking

A mechanism in which auditory neurons fire action potentials in sync with a particular phase of a sound wave, providing frequency information.

Auditory Nerve

The nerve that carries auditory information from the cochlea to the brain, tonotopically organized according to frequency.

Tectorial Membrane

A structure attached to stereocilia that interacts with sound waves, helping to deflect hair cells.

Spiral Ganglion Cells

The cells in the cochlea that connect hair cells to the auditory nerve; each has a best frequency.

Dorsal Cochlear Nucleus

The area in the auditory pathway that performs complex spectral analysis of sound.

Medial Geniculate Nucleus (MGN)

A part of the thalamus that processes auditory information before it reaches the cerebral cortex.

Neural Signals

Signals generated by hair cells in response to sound that convey information to the brain.

Traveling Wave

The wave created in the cochlea as sound moves through the fluid, resulting in vibration of the basilar membrane.

Cocktail Party Effect

The ability to focus attention on a single conversation in a noisy environment, relevant to auditory processing.

Organ of Corti

The sensory organ within the cochlea that contains hair cells responsible for converting sound vibrations into nerve impulses.

Auditory Pathway

The route that auditory information takes from the cochlea through structures such as the cochlear nuclei to the auditory cortex.

Cochlear Fluids

Fluid within the cochlea, including perilymph and endolymph, that plays a crucial role in sound transmission.

Kinocilium

The tallest stereocilium in a hair cell that determines the direction of hair cell depolarization.