Directional responses by kittens to an auditory stimulus

When we hear a sound, our nervous system is detecting sound waves—pressure waves of mechanical energy traveling through a medium. The frequency of the wave is perceived as pitch, while the amplitude is perceived as loudness.

The cochlea is a coiled structure in the inner ear that contains hair cells—the sensory receptors of the auditory system. Sound waves are transmitted to the cochlea by small bones attached to the eardrum called the ossicles, which vibrate the oval window that leads to the inner ear. This causes fluid in the chambers of the cochlea to move, vibrating the basilar membrane.

Auditory pathways constitute the complex neural circuits responsible for transmitting and interpreting auditory information from the peripheral auditory system to the brain. Sound waves are initially captured by the outer ear, funneled through the ear canal, and reach the tympanic membrane (eardrum). These vibrations are transmitted via the middle ear's ossicles to the inner ear's cochlea.
When viewed cross-sectionally, the cochlea reveals the scala vestibuli and scala tympani flanking the...

Hearing begins developing before birth. Fetuses respond to sounds in the womb through changes in brain activity, heart rate, and body movements, showing sensitivity to auditory stimulation. After birth, hearing continues to develop rapidly, supporting language learning and environmental awareness.Auditory Acuity and Sound LocalizationAuditory acuity refers to the ability to detect sounds. Newborns are especially responsive to human voices and can detect many speech sounds, although their...

Communication in infancy begins with crying, a reflexive and adaptive behavior that signals needs such as hunger, discomfort, or anger. Variations in pitch, pattern, and intensity help caregivers interpret these states, making crying an important survival mechanism during the neonatal period.Emergence of VocalizationsBy about six weeks, infants begin cooing, producing vowel-like sounds, squeals, and gurgles that often indicate contentment. Between six and ten months, cooing develops into...

Infants are born with a predisposition to perceive and categorize basic linguistic sounds. Early in development, they can discriminate sounds from many languages and detect differences in rhythm and pattern. This sensitivity may begin before birth. Newborns exposed to two languages prenatally can recognize both, indicating that fetal language exposure influences later auditory discrimination.Recognition of Familiar SoundsBy five months, infants show preferences for familiar auditory stimuli,...