Sound waves act on the auditory organs, excite their sensory cells and cause the impulses of the auditory nerve to send afferent information, which are caused by the analysis of the auditory centers at all levels.

Air vibrations of 16 to 20,000 hertz are suitable stimuli for the auditory sense, and this range of air vibrations is called sound waves. Infrasound, which is lower than 16 hertz, and ultrasound that is higher than 20,000 hertz, cannot be heard.

Hearing is an important sensory channel second only to vision, and it plays a major role in people's lives.

The frequency range of sound waves that can be perceived by the human ear is 16 to 20 00 Hz, with 1 to 3 thousand Hz being the most sensitive. In addition to the visual analyzer, the auditory analyzer is the second most important long-range analyzer for people.

From a biological point of view, with the creation of organs dedicated to hearing, sound has become not only a signal for animals to grab food or escape disasters, but also a tool for them to communicate with each other.

Auditory formation is the transmission of external sound waves through a medium to the external auditory canal and then to the eardrum. The eardrum vibrates, amplified by the ossicles, and transmitted to the inner ear, stimulating the ciliated cells in the cochlea to produce nerve impulses.

Nerve impulses travel along the auditory nerve to the auditory center of the cerebral cortex, forming the sense of hearing.

That is, the sound source ~ auricle ~ external auditory canal ~ tympanic membrane ~ cochlea ~ auditory nerve ~ auditory center of the brain.

Sound waves travel through the external auditory canal to the eardrum, causing the eardrum to vibrate. The tympanic membrane vibration is transmitted to the vestibular window through the ossicles, causing the vestibular window membrane to move inward, causing the internal and external lymphatic vibrations of the vestibular step, so that the endolympha, basement membrane, spiral and other vortices in the cochlea also undergo opposite vibrations.

The closed worm membrane also vibrates with the above vibrations, and its direction is opposite to that of the vestibular membrane, acting as a cushioning pressure.

The vibration of the basement membrane causes the hair cells connected to the epigmental membrane to bend and deform, resulting in potential changes corresponding to the frequency of the sound wave, which in turn causes the auditory nerve to produce impulses, which are transmitted to the center through the auditory duct to cause hearing.

The first-order neurons of the auditory pathway are located in the spiral ganglion of the cochlea, their dendrites are distributed on the hair cells of the cochlea, and their axons form the cochlear nerve, which enters the pontine and terminates at the medulla oblongata and pons.

The cochlear nucleus at the auditory junction, after the replacement of neurons, sends out fibers to the opposite side to form the trapezius, ascends through the midbrain hypothalamus exchange neurons, and then ascends to the medial geniculate body in the posterior thalamus, and after the neuronal exchange, the fibers are sent through the internal capsule to the temporal lobe auditory center of the cerebral cortex. When the impulse reaches the auditory center, it produces hearing.

In addition, a portion of the fibers emitted by the cochlear nucleus pass through the hypothalamus of the midbrain and descend to the motor neurons of the brainstem and spinal cord, which is the reflex arc of the auditory reflex.

In addition, in addition to the air conduction through the outer ear and middle ear through sound wave vibration, sound conduction can also cause the vibration of the intracochlear lymph in the bone of the temporal bone through the vibration of the skull, causing hearing, which is called bone conduction.

Bone conduction is extremely insensitive, and normal people's perception of sound mainly depends on air conduction.

The outer and middle ears are responsible for conducting sound waves, and hearing loss caused by lesions in these areas is called conductive hearing loss, such as hearing loss caused by chronic otitis media.

Hearing loss caused by lesions in the inner ear and auditory nerve. This is called neural hearing loss. Some drugs, such as streptomycin, can damage the auditory nerve and cause tinnitus and deafness, so caution should be exercised when using these drugs.

In general, when the sound intensity exceeds 140 decibels, the sound waves are no longer caused by hearing, but by tenderness.

The sound waves conducted by air vibrations act on the human ear to produce hearing.

The sound that people hear has three attributes. These are called sensory properties, i.e., loudness, pitch, and timbre.

Pitch intensity refers to the magnitude of sound and is determined by the amplitude of the sound wave, the physical property of the sound wave, i.e., the maximum distance from the equilibrium position when vibrating.

Pitch refers to the level of sound and is determined by the frequency of the sound wave's physical properties, i.e., the number of vibrations per second.

The unit of frequency is called hertz, and the average person hears a wide range of pitches.

The daily long wave refers to the sound with low frequency, and the short wave refers to the sound with high frequency. Sounds caused by a sine wave of a single frequency are pure tones, but most sounds are a mixture of many frequencies with amplitude.

The composite program and composition of the mixed sound constitute the quality characteristics of the sound, which is called timbre. Timbre is the main basis for a person to be able to distinguish the same pitch from different sound sources.

Auditory adaptation takes a short time and recovery is quick. Auditory adaptation is selective, that is, it only adapts to the sound of the frequency that acts on the ear, and does not adapt to other sounds that do not act.

If sound is continuously acted on for a long period of time, causing a significant decrease in auditory sensitivity, it is called auditory fatigue. Auditory fatigue is different from auditory adaptation, and it takes a long time to recover after the sound stops working.

If this fatigue occurs frequently, it can lead to hearing loss and even deafness. If only a small part of the frequency of the sound is lost, it is called a sound gap.

If you lose hearing for a large part of the sound, it is called an island of sound, and in the most severe case, you will become completely deaf.

The mixing and masking of sound means that when two sounds reach the ear at the same time and are mixed, the mixing results are different due to the different frequencies and amplitudes of the two sounds.

If two sounds are of approximately the same intensity and have a large difference in frequency, a mixture is produced. However, if the intensity of the two sounds is not much different and the frequencies are also very close, the sound fluctuation phenomenon of the frequency difference between the two sound frequencies will be heard, which is called beating.

If there is a large difference in the intensity of the two sounds, only one of the stronger sounds can be perceived, a phenomenon called sound masking.

The masking of sound is affected by frequency and intensity.

If both the masked tone and the masked sound are pure tones, then the closer the frequencies of the two sounds, the greater the masking effect, and the masking effect of the low-frequency tone on the high-frequency tone is greater than the masking effect of the high-frequency tone on the low-frequency sound.

As the masking intensity increases, the masking effect increases, and the frequency range covered increases, and the masking intensity decreases, and the frequency range covered by the masking effect decreases.

Because the average human hearing range is 20 to 64 hertz, while cats are 45 to 64,000 hertz, cats can capture ultrasound that humans can't hear.

The muscles on the cat's ears are also well developed, and through the twenty muscles in the ears, the ears can be rotated freely, and the direction of the sound can be quickly perceived.

It can be said that the cat's ears are highly developed and do not let go of the tiny sounds made by any distant prey. Cats hear three times as much as humans.

Cats have the ability to hear a high register of two octaves higher than humans. The ear determines the source of the sound by turning it quickly.

Immortals can not only use their eyes to see the night obstacles that ordinary people can't see like daytime, but also use their ears to hear sounds that ordinary people can't hear.

Thousands of ears and 100 miles of eyes, this is commonplace, not surprising.

Because the hearing of the immortal can detect the infrasound and ultrasound of one to one hundred thousand Heraz, even Xiang Jian's eyes can keenly see the thin feet of ants a hundred meters away, and count the legs of centipedes.

The five senses of immortals are much stronger than those of ordinary people, so there is nothing the people of the rivers and lakes can do to fight with immortals.

"As a saint, it's really strange, your temperament that doesn't change at some point is now here to help, if you really want to break the five-colored sky array, how can there be so much nonsense?" Ling Yao said unhappily.

"You don't know much about this, the sect and the demon clan are fighting, and now the three Qings are implicated, it seems that the victory or defeat is obvious, but in fact there are too many unknown factors. Let me ask you, do you know that the blind fairy is involved, and do you know that Princess Longji is also in this quagmire?"

"Blind Immortal, isn't it just an immortal who was blinded by an opponent's stabbing eye, but adopted the son of an enemy? Now that he is deep in the world of icicles and the fog lost to the building, what is the obstacle?" said Fairy Ling Yao disapprovingly.

"The blind fairy is blind, but his heart is not blind, with such a resolute help in the array, what is the fairy blindly worried about?" Yuan Chen said, and casually scanned the immortal island shrouded in thick fog.

"People don't lose, but they don't know what to lose. Princess Longji was born to the Golden Mother of Yaochi, the Queen Mother of the West who was the goddess of immortality in charge of immortality, punishment of evil, and early warning of disasters in ancient times. She lives in Kunlun Mountain, is the leader of the fairies, dominates the yin qi, once the sect is related to the Queen Mother of the West, then Haotian will be just around the corner. The sword said without any panic.