The hammer in the ear, also called the malleus, transmits sound vibration to the anvil from the eardrum. The hammer and the anvil, also called the incus, are two of three very small, linked and movable bones in the ear. The other is the stirrup or stapes. Together, these three bones transmit sounds through the inner ear. InnerBody states that "the small bones create fluid membrane waves by converting compression sound waves from the eardrum."
The collective name of these three bones is the ossicles, according to HowStuffWorks. The bones amplify sound waves from the air to provide sufficient pressure for the waves to pass through the inner ear.
According to the National Institute on Deafness and Other Communication Disorders, otosclerosis is a condition related to abnormal bone remodeling of these three bones. As the body replaces bone tissue, this abnormal remodeling disrupts the transmittal of sound between the middle and inner ear. The condition affects over 3 million Americans and scientists think sufferers inherit the condition. White, middle-aged females are at the greatest risk.
While some mammals have an ear structure similar to humans, other animals are less similar. Birds retain the outer ear, middle ear and cochlea structure, but they have a single bone in the inner ear. Fish, reptiles and amphibians do not have a cochlea. Instead, they use a simpler auditory or vestibular organ to detect low frequency sounds, according to Reference.com.