The quality of sound is subjective and abstract. The higher the reduction of sound, the better the quality of sound. In short, the closer you get to the real sound quality, the better you can distinguish the different types of instruments, the sounds of various instruments and the sense of presence. The sound quality is closely related to many factors. Here are six key points to evaluate sound quality:

1、Stage performance of sound field
The spatial sense of the sound field is closely related to the speaker positioning: the three-dimensional height, width and depth of the sound field extend to the wall, and this height, width and depth will form the shape of the front convex and back concave or relatively flat or square or rectangle or ellipse, that is, the overall sound field spatial sense shape extending up, down, left, right, front and back. This sound field shape is the spatial sense of various shapes, and the best spatial sense is to diffuse the entire listening room In addition to good equipment, there is also a proper space size, too small space is difficult to achieve a perfect sense of space. The level and sense of location of musical instruments and human voice in the sound field refers to the three-dimensional and the change of depth or distance of musical instruments in the sound field, and the sense of location refers to the left, right, up and down positions of the three-dimensional sound field of the sound body. With a good sense of hierarchy and positioning, all kinds of musical instruments and vocals have a sense of three-dimensional shape. If the sound system equipment is not good enough or the speaker is not well positioned, you cannot hear the sense of shape, especially the sense of depth. The overall sound field should be formed on the stage behind the left and right loudspeakers. If the sound rushes forward, it's not right, especially if the low frequency shows the feeling of pounding the chest when rushing forward. For a while, I think it's the strength of the high volume. But if I listen for a long time, it will be very uncomfortable, and it's an incorrect performance.

2、Transparency and clarity of sound
The transparency of the sound field is related to the music itself and the cleanliness of the background, and it is related to the contrast of S + n / N in terms of instrument measurement. It has a good sense of transparency, good sense of space, and good definition. The sound field must be flat without depth, and the sound image is large or even paste into a group. The common bass hypertrophy is an example, or the bass paste into a group. Some people think that the low frequency is thick and powerful, which is actually wrong. It can be compared when listening to the live music performance. Clarity is often confused with the phenomenon that the middle and high volume senses are more and more bright. The middle and high volume senses are more and more bright, and the overall low frequency proportion is reduced. The sense of hearing is not natural. If there are more lip and tooth sounds at the same time, it will be harsh. It is difficult to do well in low frequency definition, which can be identified from the degree of microseismic identification of big drum skin rhyme or double bass string.

3、Resolution and detail of sound
Only when the resolution is strong, can there be many details. Generally speaking, the low-frequency resolution is the most difficult for the sound system to do well. Only when there are many details, can you hear the micro vibration (or loose fragrance) of the strings, the wood smell of the moment when the piano strikes the mallet, the extension of the rhyme and the resonance between the steel strings and the cavity, the reflection board of the piano, as well as the emotional expression of the faint breath of human voice, and the low-frequency is like the moment when the drum skin is hit by the mallet Tension and extended rhyme.

4、The balance of high, middle and low frequency
The balance of the high, medium and low frequency bands of the sound can be pleasant. Too bright (too many high frequencies) especially the lip and teeth sound is hard, too dark (too few high frequencies) is not vivid, the low frequency expansion (too many) will flood the theme, and the lack of low frequencies will be like the lack of things in the footwall, the lack of integrity, or the medium frequency too blunt and not thick enough, the lack of warm and rich sweetness will become dry and astringent.

5、Cohesion of sound and sense of form
The cohesive force and sense of form of sound refer to the well focused, non haloing and non dispersive instrument or mouth shaped or cohesive drum sound, as well as the size ratio of human voice and instrument, which is related to the phase distortion of the instrument and the diffusion angle and response speed of the loudspeaker, and also has a great relationship with the angle adjustment of the TOA in speaker. The system that is not delicate has halo, large body, non proportional, cohesive force and sense of form The music stage is not formed or incomplete, and cannot achieve the natural and huge stage effect.

6、Vitality and liveliness
The contrast of the sound strength of the performance (singing) track is the dynamic size, which directly shows the dynamic level of the live sound. The dynamic level is the same as that of the recording site, which means the lively sense of vitality. After the dynamic level is compressed, the sound will become dull and not vivid. The response speed of the general sound is fast and slow, which is related to the speaker unit and amplifier. If there is no detail and dynamic level, the sound will become flat It's bland and boring. At this time, the sound has no depth, few levels and weak contrast. The sound performance is very flat and not vivid. You can only listen like background music and not really listen to it. It's dynamic, with many details, and the sound is naturally sweet. It's just a lively sense with vitality, which can convey the true feelings of music "sound and motion".