The properties of sound quality are divided into three main properties of tone, loudness and pleasantness (timbre) and concordance, and four sub-properties of smoothness, brightness and fullness.

Test indicators of sound in each frequency band:
    (1)、High pitch: Transparent and bright; Soft; Good sense of extension;
    (2)、alto: Full and delicate; Round and clear;
    (3)、Low pitch: Have a sense of energy; The transient response is easy to send and receive, crisp; Dive very deep;

Explanation of common evaluation terms:
    (1)、Broad voice: It indicates that the frequency band is wide, the distortion is small, the linearity is good, the dynamic range is large, and the distribution is uniform, the middle and low frequency energy is prominent, the reverb ratio is suitable, and the sound feeling is wide, full and comfortable. (Good comment on the box)
    (2)、Narrow voice: Lack of treble and bass, narrow frequency band, narrow range, short reverb or medium frequency is too prominent, treble lack of level, bass is not full enough. (Bad comment on the box)
    (3)、Bright sound: Also known as clarity or brightness, in the entire range of sound, low and medium tone moderate, treble energy is sufficient, especially in the 2~5kHz frequency band has been improved, and there is a rich harmonic. At the same time, the reverberation ratio is suitable and the transient response is good.
    (4)、oversound: The high frequency energy is excessive enough to produce a harsh sensation. Professional engineering boxes are more significant.
    (5)、Dull voice: Lack of high frequency and medium high frequency, especially in 5~6kHz above there is a significant attenuation, medium and high frequency reverberation time is short, listening to the sound feeling dark and no luster.
    (6)、Soft voice: One is a good evaluation, which refers to small distortion, small damping, low frequency and medium frequency, appropriate reverb sound, low frequency frequency response is wide, sound is relaxed, and listening feels soft and comfortable. There is also a poor evaluation, which means the lack of medium and high pitched, the theme is not prominent enough, and there is no strength.
    (7)、Hard sound: Lack of bass, more middle and treble, and high audio harmonic decay is too short and too fast, low frequency reverb sound is short, there is obvious intermodulation distortion, transient response is not good, poor damping. In the electroacoustic system or recording and playback process, there is a little overload phenomenon, which will produce a hard sound sensation.
    (8)、Thick voice: The bass and mid bass have plenty of energy, moderate reverb and no distortion. The sound feels full bass. Thick and powerful. It's a good evaluation of sound.
    (9)、Thin voice: Low frequency response is not good, the average sound energy is low, the bass and mid bass energy is insufficient, and the reverberation is not enough. The sound is lacking in intensity and resonance.
    (10)、Flat voice: The frequency band is narrow, the sound is thin, the sound quality is endless, the distortion is large, and the fullness is not good.
    (11)、Smooth voice: The distortion is small, the frequency response is wide and uniform, there is a certain loudness and brightness, the ratio of reverb sound and direct sound is appropriate, especially in the medium and high frequency reverb sound volume, the sound is not dry, round, and watery.
    (12)、Dry voice: Listening environment sound conditions are poor, diffusion is not good, reverberation time is short, no elasticity, not bright, especially the lack of medium and high frequency reverberation sound, sounds dry, laborious.
    (13)、The sound is clear: the frequency response is wide and uniform, the middle and high frequencies are rich, the timbre is bright and the reverberation is moderate. If the reverberation time is long, the sound level is small, the noise is large, and the acoustic characteristics of the recording or listening place are poor, the sound clarity will be reduced.
    (14)、Cloudy sound: low frequency and low frequency reverberation time is too long or too much energy, the direct sound proportion is small, the main tone is not prominent enough, the lack of high frequency, poor brightness, resonance distortion or intermodulation distortion is large, the transient response is not good, and the sound feels cloudy and unclear.
    (15)、Sound explosion: the sound energy density is too large, the high frequency and middle high frequency are too much, in the electroacoustic system, the overmodulation amplitude distortion is serious, and there is overload clipping phenomenon.
    (16)、Sound breaking: the sound energy density is too large, there are serious harmonic distortion and intermodulation distortion, in the electro-acoustic system, any sound overload clipping distortion, will produce a "broken" feeling, sometimes accompanied by "splash" sound, sound breaking is also called sound splitting.
    (17)、Dull sound: lack of treble and middle treble, serious attenuation above 3~4kHz, lack of high-frequency reverberation, too much low-frequency energy, especially around 150Hz, low-frequency linear distortion is large, and transient response is not good.
    (18)、Sound drift: timbre is not strong, sound focus is weak, reverberation is too large, direct sound is not enough, sound contact is too much, lack of medium tone, sound energy average sound level is small, loudness is low, clarity is poor.
    (19)、Sound transmittance: distortion is small, transient response is good, bandwidth and uniform, high frequency and high frequency are separated, high and middle reverb is sufficient, bass is not ambiguous, there is a certain intensity, clear and bright, good layering.
    (20)、Sound paste: vague, music paste into a piece, more bass and concrete sound time is long, there is intermodulation distortion.
    (21)、Sound real: strong low frequency sound average energy level is larger high frequency and high frequency, low distortion, high loudness.
    (22)、Sound swing: Good evaluation: the low frequency has enough energy, the sound is relaxed and elastic, the low frequency reverberation is slightly larger, 80~150Hz is increased more, it sounds like the bass is full, the timbre swing. Poor evaluation: the bass is too exaggerated, the sound is out of balance, the sound source itself lacks low frequency, and the resonance caused by the low-frequency vibration peak of the speaker will produce an additional bass, auditory dull, lack of brightness and level.
    (23)、Sound wood: Bass or bass is poor, diffusion is poor, reverberation time is short, high frequency and high frequency lack.
    (24)、Sound sharp: frequency response distribution is not uniform, lack of bass and treble, especially the treble component is too much, distortion is large, feel harsh.
    (25) Coarse sound: low frequency sound energy density is large, middle and high sound is relatively small, sound color is rough, strength, clarity and reverberation are poor.
    (26) Sound contraction: the sound energy density is too small, the sound can not be sent out, the lack of medium frequency concrete has a short sound time, and the distortion is too large
    (27) Clean sound: small interference between voice parts, between instruments and between languages, high signal-to-noise ratio, no additional components, small distortion, good transient response, moderate mixing.
    (28) Sound fullness: sound thick, round, large power, a certain loudness and brightness, no lack of medium and high frequency, low frequency and medium frequency energy is sufficient, sound is sent, reverberation sound is sufficient, distortion is small, transient response is good.
    (29) Metal sound: a segment of middle and high frequency is prominent or has a resonance peak, the frequency response is uneven, the distortion is small, the underdamping, the transient response is not good, the sound quality feels hard, and it seems to be mixed with metal device noise.
    (30), tooth distortion: the tooth sound, also known as the S sound, is a reaction of the higher-order harmonic transient distortion of the sound in the vibration process.
    (31) Intimacy: This is a high comprehensive evaluation. Requirements suitable loudness, high clarity, natural degree good reverb moderate, wide range, low distortion, low noise level, as if in a concert hall theater with good acoustic conditions to directly listen to the band's performance, listening to the sound feeling cordial, natural, immersive.