The ancient understanding of the nature of sound is very close to today's acoustic theory. In the east and west, people think that sound is produced by the movement of objects, and it reaches people's ears in some way in the air, causing people's hearing. The systematic study of acoustics began with Galileo's study of the period of a simple pendulum and the vibration of an object at the beginning of17th century. From then until the19th century, almost all outstanding physicists and mathematicians have made contributions to the study of vibration and harmony principles of objects at the same time.
The problem of sound propagation has long been concerned by people. As early as 2000 years ago, people in China and the West compared sound propagation to water ripples. 1635 someone measured the speed of sound with distant gunfire, and later the method was continuously improved. 1738, scientists from the Paris Academy of Sciences measured the speed of sound of air at 0℃, and found that the speed of sound was 332 m/s, 1827. The Swiss physicist Daniel and the French mathematician Sturm conducted experiments in Lake Geneva, and found that the speed of sound propagation in water was 1435m/s, which is only available in "acoustic instruments".
The lowest sound intensity that human ears can hear is about 10- 12W/m2, and the corresponding vibration displacement of air particles is about10-1m at 1000Hz, which shows that the ability of human ears to receive sound is really amazing. In the19th century, there was a lot of work about human ear anatomy and discussion about human ear function. 1843, ohm, who discovered the famous circuit law, put forward the theory that the human ear can decompose complex sound into harmonic components and judge timbre according to the partial sound. Inspired by Ohm's acoustic theory, people have carried out acoustic research of hearing (hereinafter referred to as physiological acoustics and psychoacoustics) and achieved important results, among which Helmholtz's perception of sound is the most famous. So far, a complete auditory theory has not been formed. At present, people know something about the process of acoustic stimulation reaching the cerebral cortex through auditory organs and nervous system, but how to analyze, process and judge the cerebral cortex after this process needs further study. Within the scope of language and hearing, theoretical research has led to the emergence of many medical devices, such as hearing AIDS, artificial larynx, speech synthesizers, cochlear implants and so on.
Listen to language and music in closed spaces (such as rooms, classrooms, auditoriums, theaters, etc.). ) Some effects are very good, while others are very poor, which leads to the research of so-called architectural acoustics or indoor sound quality today. But it was not until 1900 Sabin got his reverberation formula that architectural acoustics became a real science.
In 1877, Rayleigh published two volumes of Principles of Acoustics, which collected a large number of acoustic research achievements in 19 century and two or three hundred years before, and created a precedent for modern acoustics. So far, especially in theoretical analysis, these two volumes are often cited. The telephone theory he began to discuss has now developed into electroacoustics.
In the 20th century, due to the development of electronics and the use of electroacoustic transducers and electronic instruments, sound waves of any frequency, any waveform and almost any intensity can be generated, received and utilized, which has made the scope of acoustic research far incomparable. The first branch of modern acoustics is architectural acoustics, electroacoustics and corresponding electroacoustic measurement. Later, with the expansion of frequency range, ultrasound and infraacoustics were developed; Due to the improvement of means, hearing has been further studied and physiological acoustics and psychoacoustics have been developed; Because of the study of language and communication, language acoustics has been developed.
In World War II, ultrasound was widely used in underwater detection, which promoted the great development of hydroacoustics. Since the beginning of the 20th century, especially since the 1950s, due to the great development of industry, transportation and other undertakings, the problem of noise environmental pollution has emerged worldwide, which has promoted the development of noise, noise control, mechanical vibration and shock research. The application of high-speed and high-power machinery is more and more extensive, and nonlinear acoustics is paid more and more attention. In addition, there are musical acoustics and biological acoustics. With the development of multi-disciplinary branches, a complete modern acoustic system has gradually formed.