How do ears transmit sound? How does sound travel in the ear?

There are two mechanisms by which sound is transmitted to the human ear: air conduction and bone conduction. Air conduction is conducted through air, and bone conduction is transmitted into the ear by vibrating the skull.

Air conduction propagation: sound waves, auricle, external auditory canal, tympanic membrane, malleus, anvil, stapes, vestibular window, external and endolymphatic fluid, spirochord, auditory nerve, auditory center.

Bone conduction propagation: sound waves, cranial vibration, external and endolymphtic fluid, spirals, auditory nerve, auditory center.

Sound can reach the human ear through two pathways: air conduction and bone conduction.

Listening to others is one way of air conduction, and listening to oneself is two ways: air conduction and skull vibration.

There are two ways for sound to enter the ear, bone conduction and air conduction.

Bone conduction: Sound can also be transmitted to the auditory nerve through the skull and jawbone, causing hearing. In science, this conduction of sound is called bone conduction. Some people who have lost their sense of hearing can use bone conduction to hear sounds.

Air conduction: The vibrations of the sound waves are collected by the pinna and pass through the external auditory canal to the tympanic membrane, causing mechanical vibrations of the tympanic membrane and the ossicular chain, which transmit the vibrations of the stapes foot plate through the vestibular window to the external lymph of the inner ear. This pathway is called air conduction.

1.Mode of transmission.

Sounds from the outside world first cause the eardrum to vibrate, and this vibration is transmitted through the ossicles and other nerve tissues to the auditory nerve, which transmits information to the brain so that the person can hear the sound. This process is very tight, and if there is a problem in any of the links, it will lead to deafness.

2.Binaural effect.

People have two ears, and the distance between the sound source and the two ears is generally slightly different, that is to say, the moment of the sound coming into the two ears, the strength of the sound and so on are different.

These differences can be used as the basis for judging the direction of the sound source, which is called the binaural effect.

Sounds from the outside world cause the eardrum to vibrate, and this vibration is transmitted to the auditory nerve through the ossicles and other tissues, and the auditory nerve transmits the signal to the brain, and the person hears the sound.

tympanic membrane - incus - semicircular canal - auditory nerve.

The pinna first collects the sound and transmits it to the ear canal, and the sound waves of the sound will vibrate the eardrum, and then the three ossicles behind the eardrum will vibrate, stirrup to the window of the inner ear, and vibrate the fluid in the inner ear, and the liquid will stirrup the nerve cells after vibrating, and the signals generated by the nerve cells will be uploaded through the auditory nerve, and finally transmitted to the brain, so as to hear the sound.

Sound is an invisible sound wave formed by different air pressures, high and low, which can be perceived by the human ear.

It seems like a simple ear, but it is actually a big family. Exposed, what we usually call the ear is called the pinna, and it is an open door.

Sound waves enter the ear canal from the pinna and vibrate the eardrum. The eardrum is a small, tight skin that sound waves cause it to vibrate. The eardrum is connected to a small bone called malleus, and the vibration waves are transmitted from the malleus to two other small bones, the incus and the stapes, and then to the cochlea.

The cochlea is a snail-shell-like tube filled with fluid. As a result, the fluid of the cochlea fluctuates and pushes the cilia that protrude from the fluid in rows of specialized hair cells, which are normally only visible under a microscope.

Ciliary movement generates nerve signals that are transmitted to the brain through nerves in the human body that resemble a thread. In this way, we hear the sound.

There are two ways of sound conduction: one is air conduction, that is, sound waves are transmitted to the auditory center through the external auditory canal - tympanic membrane - ossicular chain - round window membrane - endolymph - vibrating basement membrane hair cells - auditory nerve fibers. In this way, if one link is affected, the transmission of sound will be hindered; This is why in patients with purulent otitis media, after a perforation of the eardrum, hearing loss.

Another route is bone conduction, in which sound waves vibrate the endolymph through the skull – vibrating the basement membrane.

hair cells – transmit sound to the auditory center. This is why patients with purulent otitis media still have hearing after tympanic membrane perforation.

Not everything is heard by the human ear, only sounds with vibrational frequencies in the range of 20 20,000 hertz can cause hearing. There are two stages of auditory production, the first stage is called the process of sound conduction. The structures involved in sound conduction are the cochlea of the outer, middle, and inner ears.

There are two paths for sound to enter the inner ear: one is air conduction, and its process is as follows: the sound is collected through the external auricle to the external auditory canal, but it causes the tympanic membrane to vibrate, and then drives the malleus to move, and transmits the energy to the perilymph of the inner ear through the vestibular window after the stapes floor vibrates, and the perilymphatic flow is like water in a bottle, driving the fluctuation of the basement membrane in it.

In this process, the role of the pinna is to collect sound and identify the direction of sound. The pinna of the human ear has degenerated, and it is not as large and flexible as other animals and can move around, so sometimes listening to sounds requires the hand to put on the pinna or turn the head to help. The external auditory canal, on the other hand, pressurizes sound and protects the deep structures of the ear from damage.

During the air conduction of sound, the ossicular chain composed of the tympanic membrane and the three ossicles plays the greatest role. Because the eardrum is a thin membrane, its vibration frequency is generally the same as that of sound waves, which can best sense the changes of sound waves and can amplify the energy of sound waves by 17 times. The ossicles are connected into a chain of ossicles in the form of the most ingenious levers, which multiplies the sound energy.

The second is bone conduction, which can cause the vibration of the skull, and transmit the sound wave energy directly to the perilymph to produce hearing. It seems a little strange to see that the sound waves that can't be grasped can vibrate the hard and heavy skull? But this is true, and there are two ways: mobile bone conduction and compression bone conduction!

It's just that bone conduction is not the main way in the process of sound conduction. The second stage of auditory production is the sensory process of sound, which is mainly done by the cochlea of the inner ear. When the sound of air conduction and bone conduction vibrates the perilymph, it also fluctuates the basement membrane that grows within it.

The basement membrane is like a row of toothbrushes that go from long to short side by side. The energy of the sound waves causes the "toothbrush bristles" (i.e., the ciliated cells on the basement membrane) to bend or deflect, and this bending and deflection generates electrical energy, which travels along the "toothbrush handle" to the nerve center to produce hearing. Sounds of different frequencies can always find a suitable "toothbrush" to pair with the best resonance.

At this time, the basement membrane acts similarly to the generator of a hydropower station, converting the mechanical energy of the water flow into electrical energy.