Bone Conduction
A way in which sound waves are transmitted to the inner ear: The sound waves travel directly through the cranial pathway, causing the perilymph to fluctuate accordingly, and activate the spiral organ of the cochlea to produce hearing. Osteoconduction means that the directed osteogenic precursor cells from the host bone surface and the bone marrow around the implant bed extend into the surface of the implanted bone and its cavities through proliferation, and generate osteoblasts to form new bone.
I. Overview:
This is actually because of skull sound transmission!
This is because the transmission channels of sound waves are different. The external sound heard by the human ear is the vibration of the external air that transmits the sound information to the auditory nerve through the eardrum, and the processing of the brain forms what we call hearing. The sound we hear when we speak by ourselves is directly transmitted by the skull to the auditory nerve from the vibration of the vocal cords from the inside, and another kind of hearing is formed after processing by the brain.
That is to say, the former spreads through the air, allowing others to hear the sound; the latter spreads through the skull, allowing oneself to hear the sound.
Why is there such a big difference between the two modes of transmission? In fact, this is because the sound transmitted through the air is affected by the environment, and its energy will be greatly attenuated, resulting in a great change in the timbre, and when the sound reaches the inner ear of others, it also passes through the outer ear, eardrum, and middle ear. This process also Affects the energy and timbre of the sound. The sound transmitted through the skull directly reaches the inner ear through the bone between the throat and the ear, and the attenuation and change of the energy and timbre of the sound are naturally relatively small. Therefore, the hearing caused is not the same.
In normal auditory function, the sound energy transmitted to the cochlea by bone conduction is very small and has no practical significance.
The principle of bone conduction
It starts with how we hear voices. Under normal circumstances, sound waves are introduced into the inner ear through air conduction and bone conduction, and then vibrate by the inner and outer lymph fluids of the inner ear. After comprehensive analysis of the cortex, the sound is finally “heared”. Perhaps for air conduction (the path is sound wave – auricle – external auditory canal – tympanic membrane – malleus – incus – stapes – vestibular window – external, endolymph – spiral organ – auditory nerve – auditory center), we more or less have some Perceptual understanding, but bone conduction is somewhat ignorant. Maybe you will understand with an example: cover your ears with your hands, talk to yourself, no matter how small the voice, we can hear what we say, this is the result of bone conduction.
The way of bone conduction
There are two ways of bone conduction: moving and squeezing. The two synergistically stimulate the auger to cause hearing. The specific conduction path is: “sound wave-cranium-bone labyrinth-inner ear lymph fluid-spiral-auditory nerve-cerebral cortex auditory center “. Usually people do not need to use their skulls to feel the sound, but when the lesions of the outer ear and middle ear block the transmission of sound waves, bone conduction can be used to compensate for hearing. Such as bone conduction hearing aids, bone conduction headphones, etc., is to use bone conduction to feel the sound.
For example, plug your ears with two cotton balls. Take a tuning fork and tap it several times with a rubber mallet to make the tuning fork vibrate, but its vibration is so soft that your ears cannot hear it. Put the ends of the tuning fork handle against your frontal bone, skull, and cheekbones, so that you can clearly hear the vibration of the tuning fork. Once the tuning fork handle is out of contact, the sound disappears immediately.
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