The influence of indoor acoustical environment speaker placement

One, the influence of the indoor acoustic environment

In a multichannel audio system, currently with dolby logic four directional track the most representative, it is still the most popular to the multichannel sound system. Due to surrounding the way using the two used two surround speakers around the track, the system need five speakers. Since the advent of dolby AC - 3 digital multichannel system, discrete channel quickly became a home theater 5.1 multichannel new standards.

Indoor acoustical environment of multichannel speaker have effects on indoor acoustic field, created by different room have the space of different acoustic characteristics. Multichannel audio system is to use multiple speakers to express the acoustic image positioning, build surround sound effect, this was not an easy thing, if there is no ideal indoor acoustical environment to cooperate, so comprehensive acoustics wouldn't be good. Sound psychology according to the theory of the direct sound later indoors the early reflections of less than 1 ms, has significant interference to direct sound, can make the sound more cloudy, which affect the acoustic image positioning. Between 1 ~ 30 ms early reflections on the interference of direct sound less, it has to do with the direct sound together, help to enhance the loudness, but may change the direct sound tone. As for 30 ms later reflections, the human ear is generally thought that it was the sound reverberation. For these reasons, we have to do with indoor audio-visual sound absorption, diffusion, sound insulation, such as acoustic processing, otherwise, too much reverb will lower voice clarity and consistency, affect the replay sound effects.

To build stereo field grand movie theaters, audio-visual shoulds not be too small, with room condition permits should be equipped with sound-absorbing materials.

Second, the speaker placement

On the premise of good indoor acoustical environment, the more accurate acoustic image positioning, sound more realistic nature, the more can show a vivid effect of the unity of acoustic image and telepresence. Information on the speakers put first look at the movie theater. Below is a real movie theater with surround sound of each channel speaker layout.

Front left and right channel speakers each other almost like movie screen wide apart, in front of the speakers are generally emissions behind the movie screen, they can check the tiny screen space to transmit sound to the audience. So the speaker can be placed where half the height of the screen.

Subwoofer speakers do not necessarily in the front speakers group is symmetrical;

Cinema has many standard only surround speakers, these speakers with the front speakers, truly "around" the audience put.

After putting the instance reference the speakers, we back to see how speakers should be placed to award for best sound effects. Here, we should pay attention to a problem, is that we met played indoor space may be cinema is much smaller than real. The following, we first discuss the three little ahead (left, middle and right speaker placement method, then the surround sound box, finally studies the subwoofer speakers put.

1. The vocal tract of speaker placement

As far as possible in the front speakers are usually placed in a location near the center of the image screen. Vocal tract of speaker quality had the greatest influence of movie dialogue, in order to ensure accurate positioning dialogue in the middle of the screen and the sound is clear, should use specially designed for track of individual speakers, rather than by ordinary bookshelf speakers or internal speaker instead of TV.

Central channel speaker mostly adopts horizontal horizontal box body, the optimal placement is at the top of the TV (if it adopts front projection screen placed behind the screen), which should be close to the screen. If as a result of the limitation of room space, can use more economic to put solution, namely, do not set the speakers. But the working mode of AV amplifier should be placed in the "illusion" in the track mode, make the channel of information from the left and right speakers out of equilibrium, the acoustic image right in the middle of the screen is, it is suitable for small listening room. Of course, the best or a single set of speakers.

2. The left and right channel main speaker placement

The two speakers placed has relationship with the position of the vocal tract of speaker. In order to guarantee the acoustic image of left and right to move, they should be put on both sides of the vocal tract of speaker, and the three speakers to listen to screen the best equal distances from the position of the talker. In general, than in the placement of the speakers should left and right two speakers back some distance, until the sound field can completely together, jointly build a truly unified acoustic image positioning. Back the distance and space size, position related to the speakers to listen to, can take a test to determine. In addition, the left and right channel speakers/treble in vertical height for its speakers in the axis of the loudspeaker not higher or lower than 0.3 m advisable slightly lower (preferably), or the height of the left, middle and right three speakers vary too much, the acoustic image ahead in the lateral shift will give the feeling of acoustic image jump. Usually, the floor speakers can meet above requirement. If the book posture speakers for left and right speakers, should be fixed on the speaker stand them, making it highly meet above requirement

Distance from left and right channel speaker screens related to the size of the screen. If in a small room with medium and large screen color TV, the left and right channel speakers on both sides can be close to the screen. If the screen is small, can make them a little distance away from the screen in order to obtain a broad stereo field. But also don't far away from the screen over, lest because of acoustic image position from the picture is too far and give a person the sense with false. From this point there is a "natural" - the deficiency of the environment is too small. To sum up, left, middle and right three channel speakers sound directivity over diffusivity, i.e. the three channels of radiation Angle range should be mainly toward the best listening position. So can reduce from the floor, wall and roof of reflections, appropriate to ensure that the acoustic image positioning clarity.

3. The surround channel speaker placement

Surround speakers are used to build the environment atmosphere, in the whole sound system also occupies very important position.

The types of a. surround speakers

Currently, surround speakers there are two types, one is ordinary unipolar small speakers, they are usually placed in high sound box on the shelf or hang on the wall. Another type of surround speakers are THX recommended dipole type sound box, each box has two back-to-back installed inside the speaker, they all take into reverse way. This kind of speakers (computer only high frequency sounds and sending out of low frequency sound (even to its input low frequency signal due to offset the effect also couldn't send the bass). Why is this so? Let's to see the working process of the dipole type speakers, speakers placed back-to-back within two speakers, for the two speakers in opposite phase signal, A moment is A loudspeaker input signal polarity, the box forward movement, compressed air (density) ahead at the same time, speaker B negative polarity input signal, the low box of backward motion, make its sparse (density decrease) in front of the air so two front speaker sound wave direction, on the other hand, if the two speakers are feed into the whole frequency band signal, the low frequency because of its wavelength is longer than the diffraction effect is strong, such A low frequency sound from the speaker diffraction has been weakened to the speaker B (offset); And the high frequency signal because of its shorter wavelength diffraction in the speakers on both sides of the poor ability of high frequency sound is small, so the speaker in front of offsetting effect is not obvious, allowing two speakers (computer only in the high frequency sound and a low frequency sound. The purpose of using dipole type sound box is to avoid too obvious directivity.

For sound world, dipole type sound box is a kind of very strange type, the speaker only after a certain development to mature stereotypes. This amp is not all frequencies, because of below 100 MHZ frequency has been whittled away. Use this speaker, because it only back and forward at the same time not audible to the listener's side, and make sound before you reach the listener listening room, so you can create a human auditory habits around ShengYang.

B. put surround speakers

Loop speaker should put audio-visual sound environment (room) and the type of loop speakers. Left around and right surround speakers of the two channels, the diffusivity of sound should be over its orientation, create a rich atmosphere around this advantage. Dipole when the speakers are put to focus on two factors: the resonance and failure cut yourself. The best bit anti resonant is away from the ceiling (or ground) 20% of the interior space height (such as indoor height of 2.5 m, the best position for the upper and lower 50 cm). In order to make more smooth frequency response can add a low frequency "trap" of the new device (low absorption audio) to eliminate the cause sound reflection from failure.

For direct radiant circle speakers, to consider the layout of a lot. For example: fixed on the wall on both sides, and make them to the rear corner of the room; Fixed on the rear wall, make them outward and upward and open a pour eight toward the wall and ceiling junction; On the floor against the wall on both sides, and pointing upward and the junction of the ceiling, wall, etc. Also can design according to specific situation room many other options. Home theater surround sound field mainly rely on indoor all the sound face surround speakers sound reflection and refraction to form in the different rooms of indoor acoustics conditions differ in thousands ways, as long as the patience test, compare carefully, we will be able to find the best solution.

4. The subwoofer speakers put

Usually the subwoofer speakers on the corner near the best more than 1 m away from the corner, which can reduce the standing wave interference. Also can put the subwoofer speakers on the best listen to both sides of the position, keep a proper distance, because the human ear for coming on both sides of the subwoofer direction is not very sensitive, so at this time subwoofer will not interfere with the front three channel original acoustic image positioning. Of course, the best placement should be to pass the test to decide.

The following methods may help to find the best placement subwoofer speakers. Put the subwoofer speakers on the best listening position move near the sundry (temporarily), then good its horn line and repeatedly play a music has strong bass effect, and then around the room around. Listen carefully, asked the ear to the ground, roughly in the position of the subwoofer speakers height. Listen, identify the most stable bass, the most deep and clear point, namely the best placement for the subwoofer speakers.

With the coming of information age, the rapid development of computer multimedia technology, network technology widespread application, to command the monitoring center, the establishment of the network management center, small to a temporary meeting, technology lectures, are eager to get the big picture. More color and high brightness. The display effect of high resolution, and the traditional CRT monitor is hard to meet the requirements of people on this. In recent years the rapid development of large screen projection technology is an effective way to solve large color screen display, application range further expand, the market also because of the increase in demand is active. We are now on how to choose the projector do the introduction.