有关声的资料（Information about sound）.docVIP

有关声的资料（Information about sound） On the basic nature of sound How does sound come into being? Language, singing, music and sound effects, as well as the sounds of nature, are produced by vibrations of objects. For example, if we put our hands on the throat, we feel the throat vibrate. The vocal organs (vocal cords), the strings, the hitting surfaces and the films of a musical instrument, when they vibrate, make the surrounding air particles vibrate with the density change, and form a density wave, that is, sound waves. The sound produced by the vibration of an object must be transmitted by the opening of a vacancy or other medium before we can hear it. Without air or other medium, we could not hear sound. There is no vacancy on the moon, so the moon is a silent world. Then how does the air transmit sound? We also illustrate by beating drums. When we beat drums, the eardrum vibrates and causes changes in the plane of the eardrum. When raised in the tympanic membrane, as shown above A in the air by the tympanic membrane tympanic squeeze and density change, forming dense department. This part of the air density will squeeze the air at the nearby B B, the air has become the trend of. But the eardrum is fast and concave. As shown, the surface of the eardrum forms a gap, and the air density at A becomes smaller and forms a sparse part. At this time, B air is being squeezed into a secret department, and the C air into a compact part of the trend. When the eardrum is raised again, as shown, A air by squeeze back into a dense tympanic membrane, B air in the air in the process of extrusion C, their density became sparse, C air into dense portions. In this way, the eardrum vibrates back and forth, causing the dense and sparse parts to pass rapidly from one gas layer to another. Thus, sound waves travel in all directions and sound waves are formed. In fact, only the air particle in place near the vibration, and not with the sound travels far away, it is like we have to calm wate