The Norsonic Nor1255 Electronic Single-Level Acoustic Calibrator is a small, battery-operated Class 1 microphone calibrator conforming to IEC 60942 and ANSI S1.40. It generates a constant sound pressure of 114 dB @ 1kHz. The all-digital design with a quartz-controlled signal generator ensures a frequency stability not available on other calibrators. The reference microphone and accompanying control circuit maintain a constant sound pressure level inside the calibration coupler and automatically adjust for changes in load volume, temperature, humidity, and barometric pressure. Each calibrator is supplied with an individual accredited calibration certificate.