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On the Basis of Acoustics - Sound

The sound is the vibration of the "elastic" medium felt by the human ear, which is the rapid and small fluctuation of the pressure.

"Sound" generated in the vibration of the object, the formation of vibration "sound". Such as the cone of a speaker, a toggle, and so on. This medium can be a gas, it can be liquid and solid. After being disturbed by the vibration of the sound source, the molecules of the medium also vibrate, so that the energy propagates outwards. It must be pointed out, however, that the molecules of the media are only vibrating back and forth near the equilibrium group before they are undisturbed and are not moving steadily along with the sound waves. Media molecules vibrate to the human ear, will cause the vibration of the human ear membrane, and ultimately through the auditory nerve and produce vibration. This vibration causes the change of the density state of the adjacent air mass, and then passes along the medium to the distant mass, and finally arrives at the receiver. During the propagation of the sound wave, the vibration direction of the air particle is parallel to the propagation direction of the wave , So the sound wave is the longitudinal wave. People through the auditory organs feel the sound, the sound is a physical phenomenon, different voice people have different feelings, the same voice of the feelings will vary from person to person. Wonderful music is fascinating, clear and passionate speech is encouraging, but sometimes, the music came from the neighbors makes it difficult to sleep, the sweet words between others may be annoying. Architectural acoustics is different from other physical acoustics. The main purpose of the study is to make people get a good sound environment in the building. The problems involved are not limited to the sound itself. It also includes psychological feelings, architecture, structure, material science and even group behavior And many other issues.

The lower limit beats earphones of hearing is 0db, less than 15db environment is extremely quiet environment, quiet will make people know what to do. Most of the night of the village is 25-30db, in addition to careful to be able to experience the water, wind, small animals and other natural sounds outside, the other feeling a quiet, which is living in the hustle and bustle of the city people pursued the Pure Land. The city's night will vary from region to region. More quiet area of ??the room is generally 30-35db, if you live in the downtown area or near the traffic trunk, will have to endure 40-50db (or even higher) noise, if the neighbor is an unreasonable person , Breek when the dead of night, loud noise, and perhaps more suffering suffering. People speak the voice of the normal is about 60-70db, shouting up to 100db. In the Chinese restaurant, often due to the lack of sound treatment, voices, the sound will reach 70-80db, there are foreign reports reported noise will affect the health of the meal. Ear hearing limit is generally 120db, more than 120db of the sound will cause hearing damage, 140db sound will make people lose hearing. High-decibel speakers, heavy machinery, jet aircraft engines and so can produce more than 120db sound.

Ear hearing is very sensitive, normal people can detect 1db sound changes, 3db differences will be significantly different. There is a masking effect in the human ear. When a sound is higher than another sound 10db, the smaller sound is difficult to be heard and understood due to concealment. Due to the masking effect, in the 90-100db environment, even the close speech will hear Unclear. People have the ability to perceive the sound frequency, the voice of high frequency people will have "treble" feeling, the voice of low frequency people will have "bass" feeling, ears normal hearing frequency range is 20-20khz. Human ear canal similar to a 2-3cm tube, due to the frequency of resonance reasons, in the range of 2000-3000hz sound is enhanced, the frequency of consonants in the language dominate, is conducive to listening to the language and communication, But the ears of the earliest aging frequency is also within this range. Generally believed that 500hz below for the low frequency, 500hz-2000hz for the frequency, 2000hz above high frequency. The frequency range of the language is mainly concentrated beats by dre studio in the intermediate frequency. The hearing sensitivity of the human ear is different due to the difference in frequency, the lower the frequency or the higher the sensitivity, that is, the same size of the sound, the frequency sounds more than the low frequency and high frequency sound KTV sound.