The solidaries of stereo sound dilatation forms are uniformity and layered sense of acoustic image unity. In the actual application of the electronic sound sound system, the 70mm theaters mostly use the stereo -sound sound system, which has reached the high unity of sound and video, creating a realistic three -dimensional sense and space. However, as far as most theater and auditorium in China are concerned, only a few are used in three -dimensional sound. Because in the theaters and auditoriums that use stereo sound dilatation, you can not hear the perfect stereo effect on the seat. Because many three -dimensional soundproof theaters and auditoriums, the sound effects on some seats are often worse than when using a single channel. The reason for the above phenomenon is that the effective listening area of the three -dimensional sound method of dual -channel system is not large. In the hall that adopts three -dimensional sound dilatation, in order to ensure that the audience can fully enjoy the three -dimensional sound effects, the number of seats may be greatly reduced. The design of the hall, the layout of the speaker, and the sound control operation will be more difficult. In the hall that does not take into account the lobby as a three -dimensional sound sound expansion, the effect of stereo sound dilatation is often counterproductive. As a result, a small part of the view (listening) hear a complete stereo effect, and most of the listeners did not feel the superiority of the stereo. From the perspective of audio equipment, modern electro -sound equipment generally has the basic function of stereo sound. As the core equipment of the electro -sound system, the tuning table generally has the most basic stereo function, with the "sound image (panoramic)" potentiometer, and the three -dimensional sound output of the left and right roads. Therefore According to the left and right configurations, you can perform stereo soundproof. The design of some old -fashioned halls is often difficult to meet the requirements of stereo sound dilatation. The usual method is to use the "sound image (panorama)" on the tuning table to the middle position, and the three -dimensional equipment is downgraded to a single -channel device. That is to say, the design of the electrical sound expansion system often adopts this form: to ensure the basic function of stereo sound expansion in terms of equipment; but considering the specific situation of the environmental structure and seat layout of the hall, in order to ensure that the large -scale audio effect is generally only, it is generally only only only the audio effect. Make a single sound expansion. The same is true of the electro -sound system in most song and dance halls. Many song and dance halls and multi -functional halls generally use the above schemes, that is, retaining stereo sound function in the equipment configuration, and only single sound expansion in actual use. Because the design requirements of the song and dance hall and the multi -functional hall are not unified, the formation of soundplay should also be flexible. For example, the combination of stereo and monochrome is adopted in the hall, and the stereo sound expansion is used in the guest seats, dance floor and other places in the hall, and other areas use monocular dilatation. The general principle is that as long as you ensure that all the listening areas can hear complete program information, do not have the intervention effect of sound waves due to excessive speakers and irregular places. 3) The three -dimensional sounds around the three -dimensional sound of ordinary dual -channel enhanced the three -dimensional and spatial sense of the sound image, which is a high -end sound expansion form. It has been installed in some new theaters and theater in China.