1. Background noise: Background noise is also called background noise. The studio setting is the most demanding, requiring "absolute silence," because professional microphones are so sensitive they can pick up any sound in the room. Absolute silence is different from the feeling of quietness. To go to the indoor background noise is less than 30dBA, and the strict professional recording studio is less than 20dBA.

2. Spectrum curve: The voice of the same person in different rooms may be very different. Some rooms may sound dull and some rooms may sound sharp and harsh, but when these rooms are full of furniture and other things, the voice may sound less stuffy or sharp. This is what we call the room's effect on sound. A flat frequency response curve can make the acoustic environment good, so that the room will not absorb too much high or low pitched, high and low pitched balance, there will not be more and less high pitched, or more and less low pitched.

3. Reverberation time: After the sound source stops sounding, the time needed to reduce the sound pressure level by 60dBA is the reverberation time in seconds. The process of its attenuation in the room is called reverberation process. The volume and volume of the room determines the length of the reverberation time. The room with large volume and small amount of sound absorption has long reverberation time, while the room with strong sound absorption and small size has short reverberation time. Reverberation time is too short, sound dry, boring and not kind natural, reverberation time is too long, will make the sound indistinct; If the reverberation time is appropriate, the sound is mellow and pleasant.