Ruby Electronics DT-8851 Industrial High Accuracy Digital Sound Noise Level Meter Data Logger with USB Interface Conforms to the IEC61672-1 Class 2 and ANSI S1.4 Type 2 standard for sound level measurement A & C frequency weighting Fast (125ms) and slow (1s) time weighting Analog AC/DC output for connection to frequency analyzer or X-Y shaft recorder USB interface for computerized digital sound level recording