Application of Haas effect in Theatre

Theatre is a special listening environment, although indoor, but much larger than the size of the family, because the function of the theater is different, so there are great differences in the construction of environmental sound processing. Theatre can be roughly divided into two types from the sound processing: one is the concert hall, the opera house, in the performance of concerts and operas do not use electric sound, but completely rely rely on musical instruments and voice and other natural sound (our opera sometimes requires some electric sound). The volume of theater played by natural sound can not be too large, because the sound power of human voice and instrumental sound is bound to limit, generally do not exceed 20,000 m3. The sound of the original of such a person and instrument is called "natural sound". Other concerts, such as singing and dancing, drama, drama, and acting in the open air or in large auditoriums, require sound reinforcement. Their sound sources are somewhat different in orientation. The height of the natural sound sources is not more than two meters above the table. The main speakers of the electroacoustics are above the platform. There are also audio-visual speakers at both ends of the platform. The orientation of the natural sound is mostly near the middle of the stage in the platform. The acoustic speakers of the electroacoustics are outside the platform.

In the past 20 years, the improvement of electroacoustic equipment is very fast, especially the entry of digital chips, the wide use of DSP skills, the function and quality of electroacoustic equipment has changed greatly. It has provided high quality material conditions for the stage art. However, despite the great improvement in hardware conditions, there has been little progress in the quality of sound reinforcement, and there is still much public opinion.

The use of electro-acoustic and embodied methods are based on the playing method, content needs and different, such as rock music requires high power, ultra-low voice, strong return and so on. It should embody a strong appeal, give vent to it, frighten it, and shake it to the ground. In general, drama, song and dance, drama and so on are natural, and do not require much volume.

The question of naturalness is raised because the volume of amplification in most theaters is so large that it is intolerable and difficult for the audience to hold on to the end. An old professor said: When I was invited to the theatre to see a program, if it was not a concert in the concert hall, I would put on earplugs, in case the volume is too loud to endure, but also embarrassed to leave the table, sit there fidgeting and suffering, put on earplugs can persist until the end.

In 2001, a theater in Beijing underwent acoustical renovation. From the beginning, some leaders were invited to sit in the front rows. Soon after the performances, the leaders and some of the audience left the theater, saying that they had been bombarded with loudspeakers and were dizzy and intolerable.

Sound in acting and stage artists together for artistic invention, it participates in acting, together with its own aesthetic problems, volume like cooking salt, less taste but can also eat, more mouth can not swallow and hurt the body. For example, if the singing accent of the Cheng School of Peking Opera is louder than 90 dB in the auditorium, then the echo of the Cheng School will disappear. The sound of violin reaches more than 90dB in theaters, and it will not be able to tell whether strings are still pipe music.

Stage sound reinforcement is not long before our country. For reasons of prehistory, the Chinese people, especially the younger generation, had not heard any classical or elegant music or pop music for a long time before the reform and opening up, because these were included in the list of'pedantic revolt'to be criticized. Especially after the sweeping of the Great Civilization Revolution, young people know little about other arts except "model plays". So when the reform and opening up in the future, the door of the country opened wide, the main pop songs from the south to the North all over the mountains, a moment, from the theatre to the stadium all over the country are jumping, shouting. Beijing opera, drama, concerts, local dramas and so on are in a difficult position for a long time. This situation lasted for nearly ten years. With the deepening of reform and opening up, economic prosperity, extensive exchanges between Chinese and foreign civilizations, vigorous advocacy of spiritual civilization, China's stage gradually recovered to normal, Beijing Opera, ballet, concert gradually accepted by the majority of the audience, people's appreciation level is gradually improving.

The prosperity of the economy has promoted the development of civilized undertakings, and a number of civilized facilities, such as libraries, civilized museums, theatres, museums and so on, have also been extensively renovated, which has a good effect on the progress of the people's nature of civilization. In recent years, the construction of the theatre has been completed successively in Beijing Concert Hall, Guangzhou Xinghai Concert Hall and Shanghai Grand Theatre. The National Grand Theatre has been constructed day and night. In addition, in order to get used to the needs of cultural exchanges, such as Beijing Poly Theatre, Zhongshan Park Concert Hall have been acoustic transformation.

Recently, the problem of lip-synching has aroused the discontent of the broad audience. In order to lip-synching, it is necessary to conceal the progress of lip-synching in a large volume. So denounce the loud noise of the theater.

At the beginning of the reform and opening up, the influence of pop songs was one aspect, as well as the civilized nature of acousticians. More often than not, the leaders and leaders of some art groups wanted to use large volume to create atmosphere or compensate for the lack of program creation and performance. Some artists have to take care of the sound engineer before they go on stage to "help me turn it up a little bit", so the program that makes up who's on can't go down. When the sound on the stage is loud, the noise of the audience will be improved, so it will constitute a vicious circle.

In addition to the above reasons, skill preservation is also one aspect. For a long time has been a centralized sound reinforcement, because for a long time the acting troupe's sound equipment is self-contained, the theatre does not have suitable equipment, the troupe is mobile, so the organization of sound equipment can only make an article around the platform, easy to disassemble and assemble. Over time, we are used to this method. So that when the theater has the conditions to set up modern audio equipment, it will be the same old prescription.

One of the most difficult defects of centralized sound reinforcement is the large difference between front and rear rows. A Symposium on theatre amplification was held in the summer of 2001 by a sound company. The question of the naturalness of theatre amplification was raised at that time. The host said, "When the audience appreciated the performance on the stage, they did not notice whether there was amplification, but if the electric sound was turned off, the audience immediately felt that the sound was suddenly low. Well, this clarifies the naturalness of amplification to the point that "this clarification explains the'degree'of naturalness more graphically, but it's not easy to do that.

First of all, the directors of the demand group or the leaders' identification do not expect blind guidance from this area. The second is the change of sound reinforcement skills and concepts. Why don't you enlarge the sound in concert hall? Since going to the concert is to listen to the original flavor, it's like eating raw fruit, fresh fruit people will not eat canned fruit the same reason, otherwise people can listen to CDs at home why go to the concert hall? Of course, in addition to the above reasons, there is a factor of popularity in the concert hall.

Natural degree and natural sound are two different concepts, with two different contents, but they are very close. Natural sound plays a relatively high requirement on building sound environment, because it relies entirely on the appropriate reverberation of building sound environment, reasonable early reflection sound and so on. The requirements for the audience are relatively high, and at least the audience needs to be quiet.

The natural degree of sound reinforcement is to require the sound reinforcement not to exceed the natural sound. Generally speaking, more than 10-16 dB of natural sound is enough, but the asymmetry of sound field is higher than that of natural sound, because electroacoustics can be achieved by means of technical treatment such as reasonable configuration of loudspeakers.

In foreign countries, such as Europe and the United States, the research and application of sound reinforcement naturalness has already begun, and there are several plans for theater use. Multichannel reverberation, for example, began in the 1960s and completed the transition from imitation to digital in the 1990s. This system has no enlargement effect on direct sound, mainly adjusting the time and frequency characteristics of reverberation in the hall, so it can be used in concert halls. The other is ACS (Acoustic Control System), which was first used in 1980's. It has been installed in more than 50 theaters in Europe and the United States. In 1999, the new Kwai Tsing Theatre in Hong Kong also installed ACS system. It is aimed at direct sound. The microphone is placed above the platform mouth. Each microphone covers 5-10m2. Its main function is to replace the stage reflective cover and imitate the near-reflex sound of the auditorium, adjust the reverberation time of the auditorium, and return the sound to the artists on the stage.

With the development of taste, audiences are not satisfied with the current level of primary amplification, the quality of amplification should be improved, and the methods of amplification should be changed. Now the amplification system of the theater, like the 586 of the computer, will soon be replaced by a new CPU leap. According to the trend of sound amplification system abroad, variable indoor acoustics system will soon occupy multi-function theater.

Now these devices also need to rely on imports, according to the installation of debugging is also more promiscuous. Because it takes on a lot of contents, including the adjustment of reverberation time, the adjustment of reverberation frequency characteristics, the organization of early reflection sound and so on. However, in order to test, save money can use existing equipment as the foundation, a little more equipment can make a better natural sound amplification. A brief plan is introduced as follows:

The first step is to determine the maximum sound pressure level of natural sound (including all kinds of musical instruments and human voices), which can be tentatively set at 100 dB even down to 1 m from the sound source. On this basis, the sound level ratio of the whole field is allocated.

The sound pressure level and natural sound level of the main amplifier are 100 dB. If the sensitivity of this field loudspeaker is 86 dB, the W/m should reach 100 dB. It needs to be increased by 14 dB, and stored for 10 dB. That is to say, it needs 200 W power. In order to maintain the sound image of both ends of the loudspeaker drop 5 dB, the side of the vertical sound column is 95 dB, so only 100 W is enough power. Then push backward from the platform, one door frame is the same every 7 m, but each frame is 20 ms longer than the previous one at 3 dB (see figure).

The top speaker has a 45 degree pitch angle (see figure). The two sound poles are higher than the audience seat by 2.5m. The axis of the speaker is opposite to the middle line of the audience seat. Microphone is far away from sound source, preferably using PCC. These are the simplest natural sound reinforcements for bel canto singing in theatres, plays, and singing and dancing parties. The specific organization is shown in the attached drawings.

The application of Haas effect in theatre -- imitation of variable sound field