Atp et 958 data logging sound level meter atp et 958 p the atp et 958 is a data logging sound level meter designed to meet iec 61672 1 class 2 with accuracy of plusmn 1 4db a frac12 inch electret condenser microphone ensures accurate and repeatable readings the modern ergonomically shaped grip high intensity backlight and usb interface make this sound level meter easy to use the atp et 958 has a data logging memory for 32 600 readings p atp et 958 data logging sound level meter