用于测量声音的物理尺寸，以分贝表示。分贝定义为测得的声压与人类可听阈值的参考声压的对数比，即1000 Hz声音。通过内置的滤波器，用于测量的声压接收器还可以考虑以发声单位表示的音量。在距声源一米的距离处进行测量。对于工业车辆，最大允许声级为90 dB。

        Physical dimension for measuring sound, expressed in decibel. Decibel is defined as the logarithmic ratio of a measured sound pressure and the reference sound pressure of the human threshold of audibility for the 1,000 Hz sound. By means of incorporated filters the sound pressure receivers used for measuring also allow the consideration of the volume on expressed in phons. The measurement is taken at a distance of one meter to the sound source. For industrial trucks the maximum permissible sound level is 90 dB.