People can hear the conditions of sound: ① a sound source ② a medium for the propagation of sound ③ good human hearing system ④ volume (loudness) to a certain extent ⑤ the frequency of sound (pitch) in the human hearing range of the human ear to perceive the sound of the two pathways: (1) air conduction ① Definition: through the air vibration caused by vibration of the tympanic membrane, the vibration of the auditory ossicles and other tissues through the auditory nerve, thus causing the sense of hearing, this mode of sound conduction is called air conduction. This way of sound conduction is called air conduction. ②Principle: Gas can transmit sound. (3) Pathway: Sound from the outside world → tympanic membrane vibration → auditory ossicles, semicircular canals, vestibule → auditory nerve → brain (2) Bone conduction (1) Definition: Through the human skull, jawbone to the auditory nerve, which causes hearing, this mode of sound conduction is called bone conduction. ② Principle: the indwelling body ting to transmit sound. ③ Pathway: sound → skull vibration → auditory nerve → brain Binaural effect and stereo: 1, Definition: the distance from the sound source to the two ears is generally different, the sound to the two ears of the moment, strength and other characteristics are different, these differences are important to determine the direction of the source of the sound based on the direction of the two ears, which is the binaural effect. (Figure) 2, the reason: two ears can distinguish the direction of the sound source, there are three main reasons, one is the same sound, the two ears feel the intensity of the different; the second is the same sound, the two ears feel the time of the successive; three is the same sound, the two ears feel the vibration of the pace of the difference. Deafness: 1. Definition Type Conductive Deafness A person will have normal hearing only when the outer ear, middle ear, inner ear, and brain are intact; otherwise, hearing will be affected. Some people suffered from otitis media as a child, perforated eardrum, and even the auditory ossicles are damaged, so the hearing is not good, which is called conductive deafness neurological deafness Some people, the eardrum, ossicles, cochlea, as well as the outer auricle is not a problem, but can’t hear the sound, which is medically called sensorineural deafness. 2, some deaf patients listen to the sound method If only due to conduction disorders and loss of hearing, find a way to pass the vibration to the auditory nerve through other ways, people are also able to perceive the sound. (1) the use of bone conduction: the musician Beethoven deaf, with teeth biting the end of the stick, the other end of the top of the piano to listen to their own playing the piano, to create. (2) Utilization of hearing aids: Hearing aids are used to increase the loudness to touch the sense of hearing, which is different from the bone conduction method of hearing aid. As shown in the diagram, the human ear is constructed. The auricle to the outside world sound waves collected, through the external auditory canal to the eardrum, causing the eardrum vibration, the eardrum and then this vibration to the auditory ossicles connected to it, the auditory ossicles and then the vibration to the cochlea and the semicircular canals, processed to the relevant nerve endings, the nerve endings and then the acoustic signals sent to the brain to produce the sense of hearing.