The Amprobe SM-20-A Sound Meter has been designed to check compliance with safety regulations and perform acoustic analysis by safety engineers, health, industrial and safety offices as well as quality control. The SM-20-A offers a PC interface. They use two different weighting filters required by the IEC651 and ANSI S1.4 Type 2 for audio filtering. The A weighting is for general noise sound level and the C weighting is for measuring sound level of acoustic material control in various environments (ie 94dB 1 kHz etc).