·DBA
DBA is the level used to test volume. The data ratio of dB is based on the size of noise caused by microphone receiver. Generally, the value of small UPS noise is about 35 ~ 50 DBA, which is very whisper (as in the office). The medium and large UPS is about 50 ~ 70 DBA, which is slightly smaller than we generally speech (about 75 DBA). More than 100 DBA is larger voice. The "A" in DBA is referred to the sensitivity of human hearing. DBA is caused by the electronic equipment. In addition to DBA, there is another unit known as DBC which is specially to test much louder volumes.