The Ear and Sound

Sound

Energy produced by rapidly vibrating bodies that create pressure disturbances in the air.

Ambient Air Pressure

The baseline atmospheric pressure when no sound is present.

Sound Waves

Alternating regions of high-pressure (compression) and low-pressure (rarefaction) air molecules.

Sine Waves

Pure tones with a single frequency; basic building blocks of complex sounds.

Amplitude

The height of the sound wave; psychological correlate is loudness.

Frequency

Number of oscillations per second; psychological correlate is pitch.

Timbre

The quality or "color" of sound that distinguishes different sources (e.g., piano vs. guitar playing the same note).

Pinna

The external part of the ear that funnels sound into the auditory canal.

Auditory Canal

Channels sound waves to the tympanic membrane; amplifies certain frequencies and protects the ear.

Tympanic Membrane (Eardrum)

Vibrates in response to sound waves; boundary between outer and middle ear.

Ossicles

Three tiny bones—Malleus, Incus, and Stapes—that amplify and transmit vibrations.

Oval Window

Membrane where the stapes passes vibrations into the fluid-filled cochlea.

Cochlea

Spiral-shaped, fluid-filled structure where sound transduction occurs.

Organ of Corti

Sensory organ of hearing located inside the cochlea; contains hair cells.

Cilia (Hair Cells)

Sensory receptors that bend in response to fluid movement, converting mechanical energy into neural signals.

Round Window

Acts as a release valve, bulging to allow fluid movement within the cochlea.

Auditory Nerve

Carries neural signals from hair cells to the brain for sound perception.

Basilar Membrane

Runs through the cochlea; its movement in response to sound waves bends hair cells and encodes pitch and loudness.