Ear

The ear is a sensory organ that detects sound and, in many animals, senses head movement and orientation for balance.

Outer ear: The visible auricle and ear canal that collect and direct sound toward the eardrum. Its shape gathers sound and guides it into the ear.
Sound: A mechanical disturbance that travels through a material medium as pressure waves. The ear detects sound waves rather than objects or meanings directly.
Hearing: The perception of sound through auditory processing from the ear to the brain. It is the principal perceptual outcome of the ear’s sound-detection pathway.
Bone conduction: The transmission of sound vibrations through skull bones to the inner ear, bypassing the outer and middle ear. It can stimulate the cochlea without sound passing through the usual air-conduction route.
Middle ear: An air-filled cavity containing the eardrum and three small bones that transmit vibration to the inner ear. Its bones amplify and transfer eardrum vibrations toward the fluid-filled inner ear.
Frequency: The number of repeated cycles of a wave per unit time, measured in hertz. Sound frequency strongly influences the pitch perceived through auditory processing.
Balance: The ability to maintain posture and stable orientation through sensory and motor coordination. Vestibular signals from the inner ear help stabilize posture and gaze.
Echolocation: A sensing method that infers objects from reflected sound waves emitted by an animal or device. It uses sound for spatial mapping, beyond the ear’s detection of incoming vibrations.
Cochlea: A spiral-shaped inner-ear structure that converts sound vibrations into electrical signals in the auditory nerve. Its hair cells translate incoming vibrations into signals the brain can interpret as sound.
Amplitude: The maximum displacement or pressure variation of a wave from its resting level. Sound amplitude contributes to perceived loudness and determines mechanical input to the ear.

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