Hearing depends on a series of complex steps that change sound waves in the air into electrical signals. Our auditory nerve then carries these signals to the brain. Also available: Journey of Sound to the Brain, an animated video. Source: NIDCD
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Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Get Instant Solutions When in doubt download our app. Now available Google Play Store- Doubts App Download Now
Understanding the parts of the ear — and the role of each in processing sounds — can help you better understand hearing loss. The Outer EarThe auricle (pinna) is the visible portion of the outer ear. It collects sound waves and channels them into the ear canal (external auditory meatus), where the sound is amplified. The sound waves then travel toward a flexible, oval membrane at the end of the ear canal called the eardrum, or tympanic membrane. Sound waves cause the eardrum to vibrate. The Middle EarThe vibrations from the eardrum set the ossicles into motion. The ossicles are actually tiny bones — the smallest in the human body. The three bones are named after their shapes: the malleus (hammer), incus (anvil) and stapes (stirrup). The ossicles further amplify the sound. The tiny stapes bone attaches to the oval window that connects the middle ear to the inner ear. The Eustachian tube, which opens into the middle ear, is responsible for equalizing the pressure between the air outside the ear and that within the middle ear. The Inner EarThe sound waves enter the inner ear and then into the cochlea, a snail-shaped organ. The cochlea is filled with a fluid that moves in response to the vibrations from the oval window. As the fluid moves, 25,000 nerve endings are set into motion. These nerve endings transform the vibrations into electrical impulses that then travel along the eighth cranial nerve (auditory nerve) to the brain. The brain then interprets these signals, and this is how we hear. The inner ear also contains the vestibular organ that is responsible for balance. A small portion of a rodent’s cochlea is captured in this image. In green are four rows of hair cells that respond to sound vibrations, and in red are auditory nerve fibers that convey sound information from the hair cells to the brain. Researchers at Johns Hopkins are studying the molecular mechanisms that guide the formation of hair cells. Studies such as these might be a step towards less invasive treatments for deafness in which molecular cues can be used to biologically regenerate hair cells in the cochlea. Pinna → Cochlea → Tympanic membrane → Auditory canal → Malleus → Stapes → Incus → Auditory nerve No worries! We‘ve got your back. Try BYJU‘S free classes today! Pinna → Malleus → Incus → Stapes → Auditory canal → Tympanic membrane → Cochlea → Auditory nerve No worries! We‘ve got your back. Try BYJU‘S free classes today! Pinna → Tympanic membrane → Auditory canal → Cochlea → Malleus → Incus → Stapes → Auditory nerve No worries! We‘ve got your back. Try BYJU‘S free classes today! Pinna → Auditory canal → Tympanic membrane → Malleus → Incus → Stapes → Cochlea → Auditory nerve Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses |