This page explains the features and effects of line array speakers (line array SP).

What is Line Array Speaker

Have you ever seen long vertical speakers hanging at live venues or stadiums? That is a line array speaker. If you look closely, you can see multiple small speakers connected together, embodying the name "Line Array". Why are line array speakers constructed in this way?

Line sound source and Line array effect

Before explaining the line array effect, let's first take a look at common speakers. A typical speaker has one sound source, and is also called a "point sound source" because the sound is emitted from a single point.
In contrast, the speakers that produce the line array effect are "line sound sources." A line sound source is a collection of point sound sources. Small speakers (sound sources) that emit sound at the same time are arranged in a line.

Sound from a point source spreads out in a spherical shape. Because sound travels both horizontally and vertically, sound energy is lost as the distance increases. The farther away you are from the sound source, the lower the sound level becomes., so the only way to make the sound travel farther is to increase the volume. However, if you do this, areas close to the sound source will become noisy.

In contrast, with a line sound source, the sound spreads out in a cylinder rather than a sphere. It has the property of being transmitted horizontally and difficult to spread vertically. This reduces the dispersion of sound energy, allowing clear sound to be delivered to distant locations without having to turn up the speaker volume. This is called the "line array effect."

Note: In practice, a line array is not an ideal line source. While it may exhibit cylindrical-wave characteristics over a certain range, its propagation tends to become more spherical at longer distances.

When multiple speaker units reproduce the same signal and are arranged vertically, their sound waves reinforce each other in the horizontal direction (toward the audience) while limiting sound dispersion in the vertical direction. This is the basic principle behind the line array effect.

Line array effect and Reverberation, Feedback

When using Line Array SP, in addition to allowing clear sound to reach far away due to the line array effect, it also prevents sound from flying toward the ceiling (vertical direction) and reduces reverberation, contributing to even clearer sound transmission.

It also helps suppress feedback. The reason for this is first of all, if the reverberation is reduced, the sound returning to the microphone will be reduced, and the audience will be able to hear clear sound, so there is no need to raise the volume too high. Additionally, since each unit produces a relatively small sound near the SP, this also makes it difficult for feedback to occur.

​See also this page for Reverberation.​     See also this page for feedback.

​Precautions when handling line array SP

Although line array SP seems to have only good effects, it also has some characteristics that make it difficult to use.

If mounted too high, high-frequency coverage may not adequately reach the audience area. The fact that line arrays do not easily diffuse sound vertically was introduced above as an advantage, but in this case it becomes a disadvantage. In this case, the sound the audience hears has no high frequencies, so there is a significant loss of clarity.

If so, should SP be tilted? That's not a good solution.

Even if you tilt it, the area where high frequencies can be delivered is very small. This is because (as has already been written several times) line array SP has difficulty dispersing sound in the vertical direction.