Install the sound column near the stage entrance, and point the "sound disk" to the audience. The sound beam radiates to the back of the audience hall with strong sound energy. The front row weakens each other due to the phase difference caused by the different vertical distance of the speaker, which may be lower than the sound pressure of a single speaker here, which makes the direct sound distribution of the sound field tend to be uniform. The horizontal direction of the column should not be "bunching", and there should be a larger horizontal radiation angle to make the sound field more uniform in the left and right directions.
The column speaker usually refers to 4-10 paper basin speakers arranged and combined in a straight line. The feature is that when transmitting sound in horizontal direction, the radiation angle of the loudspeaker is the same as that of a loudspeaker, while when transmitting sound in vertical direction, the radiation angle of the loudspeaker increases with the combination of the loudspeakers, especially in high frequency sound, the sound beam can be transmitted in a certain direction.
The vertical control effect of the column speaker is quite effective. In the environment with more serious reverberation, the column speaker can effectively concentrate the sound to the audience and reduce the rebound after reaching the wall.
The feature of the sound column is that it has a strong directivity in the vertical direction. The longer the sound column, the narrower the sound beam, the more concentrated the energy, and the stronger the directivity. When the length of the column is fixed, the higher the frequency, the narrower the beam and the stronger the directivity.
According to different structures, the sound column can be formed into various specifications. The smaller the area of the "sound disk", the stronger the focusing effect, the sharper the directivity, and the higher the sensitivity on the axis than a single speaker. The efficiency of the acoustic axis of the column on the main axis is higher than that of a single loudspeaker. Generally speaking, the more loudspeakers that make up the sound column, the higher the sensitivity on the main shaft and the farther the sound radiation distance.
The sound field can be more uniform and clear by reasonably controlling the suspension height and pitch angle of the column. Because the total rated power of the sound column is several times that of a single speaker, and because of the focusing effect of the sound axis direction, the sensitivity is doubled, which is more effective for long-distance sound reinforcement.
Compared with the single speaker, the low-frequency radiation efficiency of the column is greatly improved, which increases the low-frequency response and enriches the voice color. By using the directional characteristics of the column, the microphone can be placed outside the main beam (i.e. the sound is light in the up and down directions at both ends of the column) and the sound pressure is weak, which can improve the howling phenomenon and the transmission gain. In places with long reverberation time, the use of sound column can greatly improve the clarity of sound.
The directivity of the column decreases with the decrease of frequency. That is to say, the directivity at low frequency is very poor. Therefore, the vertical directivity of the column should be improved, even if the directivity at high frequency is weakened, and the directivity at low frequency is increased.
Generally speaking, the sound column can be divided into high and low frequency segments, which are connected with the frequency division network to make the long column produce low frequency sound and the short column produce high frequency sound so as to improve its frequency response. Or adopt some methods commonly used in important meeting places, use a high-frequency horn speaker to separate the voice in the frequency band above 1kHz, so as to improve the high-frequency directivity and the voice color in the high-frequency segment.
Based on the principle of acoustic filter, a layer of sound-absorbing material (such as ultra-fine glass wool) with gradually varying thickness is covered on the sound-absorbing column panel, which has the characteristics of large sound-absorbing to medium and high frequency, and the greater the thickness, the better the sound-absorbing effect. The sound-absorbing material is thickened at both ends of the sound-absorbing column, and gradually thinned in the middle, so the effective length of the sound-absorbing column is related to the frequency, and becomes shorter with the increase of the frequency, so as to improve it The frequency response of the column.
The shape of the sound column is changed into a concave or convex shape to disperse the main high frequency sound beam. The smaller the curvature radius is, the larger the divergence angle is. Generally, the radius of curvature is r = 2L. This method of changing the shape of the sound column is simple and widely used.
Unfortunately, the bass frequency doesn't go as straight as the treble frequency, and the spread angle is wide. In the space with serious reverberation environment, the wide spread angle of bass frequency may cause mutual interference of sound, and the clarity of sound may become poor. When the microphone and the loudspeaker are in the same room, it may also produce the situation of echo call.
In addition to some defects in the directivity of the vertical direction, the above methods should be used to improve the directivity of the sound column, as well as the horizontal directivity.
These problems can be solved with the help of tone controller or equalizer. In order to reduce the volume of the bass frequency, help the speech sound clear, but has a negative impact on the music reproduction.
According to the installation angle of each loudspeaker on a single loudspeaker, the loudspeaker hole on the sound column box panel can also be cut into a rectangular slit according to the principle of sound diffraction, so as to improve the horizontal direction of the high frequency segment.
As mentioned above, as an important loudspeaker, the sound column is still widely used in many occasions.