The unit of the sound level is decibels(dB) A sound of intensity/0〔听觉阈) has a sound level of0 dB The sound at the upper range of human hearing called the threshold of pain(痛觉阈) has an intensity of lw/m2 and a sL of 120 dBThe unit of the sound level is “decibels” (dB). A sound of intensity (听觉阈)has a sound level of 0 dB. The sound at the upper range of human hearing, called the threshold of pain (痛觉阈) has an intensity of and a SL of 120 dB. 0 I 2 1w/ m