Hearing (sense)

Hearing, or auditory perception, is one of the five traditional senses, and refers to the ability to perceive sound through organs such as the ear. This sense detects vibrations as periodic changes in the pressure of a surrounding medium, usually air, though water and solids can also conduct sound. These vibrations are transformed into nerve impulses and interpreted by the brain. The study of hearing is known as auditory science.

Anatomy of the Human Ear

Anatomy of Hearing

The human hearing system is composed of three main parts:

Outer Ear

• Pinna – The visible external part of the ear that collects sound waves.
• External auditory canal – The canal through which sound waves travel to the tympanic membrane.

Middle Ear

• Tympanic membrane – Also known as the eardrum; vibrates when sound waves reach it.
• Ossicles – A chain of three small bones:
  • Malleus (hammer)
  • Incus (anvil)
  • Stapes (stirrup)

These bones amplify and transmit vibrations to the inner ear.

Inner Ear

• Cochlea – A spiral-shaped organ containing the organ of Corti, which converts mechanical vibrations into electrical signals.
• Auditory nerve – Carries auditory information to the brain’s auditory cortex for processing.

Physiology of Hearing

The process of hearing involves:

1. Sound Collection – The pinna gathers sound waves and channels them through the ear canal.
2. Vibration Transmission – The eardrum and ossicles transmit mechanical vibrations.
3. Signal Conversion – Hair cells in the cochlea convert mechanical energy into electrical impulses.
4. Neural Interpretation – Signals travel to the brainstem and then to the temporal lobe, where sound is perceived.

Sound Properties

• Frequency – Measured in hertz (Hz), frequency determines pitch. Humans typically hear between 20 Hz and 20,000 Hz.
• Intensity – Measured in decibels (dB), intensity determines loudness. Prolonged exposure to sounds over 85 dB can cause noise-induced hearing loss.

Hearing Across Species

Different species have different hearing capabilities:

• Dogs and cats can hear higher frequencies than humans.
• Bats use echolocation, emitting high-frequency sound to detect objects.
• Whales communicate using low-frequency sound that travels long distances underwater.

Hearing Disorders

Common conditions affecting hearing include:

• Conductive hearing loss – Issues in the outer or middle ear.
• Sensorineural hearing loss – Damage to the cochlea or auditory nerve.
• Tinnitus – Ringing or buzzing without an external source.
• Presbycusis – Age-related decline in hearing ability.

Diagnosis and Treatment

• Audiometry – Measures hearing sensitivity.
• Tympanometry – Evaluates middle ear function.
• Hearing aids – Devices that amplify sound.
• Cochlear implants – Surgically implanted devices that bypass damaged cochlear structures.

Auditory Science

Auditory science is a multidisciplinary field involving:

• Acoustics
• Neuroscience
• Audiology
• Psychoacoustics

It explores how sound is detected, transmitted, and interpreted.

See Also

• Auditory system
• Vestibular system
• Speech perception
• Sensory system
• Deaf culture

External Links

• NIH – Hearing and Balance
• ASHA – Hearing and Hearing Loss
• WHO – Hearing Loss

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