Quest models QC10- and QC20 are accurate electroacoustic calibrators that generate a stable acoustic signal at a controlled frequency and aamplitude level. Their principal use is for a calibration accuracy check of sound level meters and oise dosimeters. Other acoustic analyzers, such as FFT or Real Time Spectrum annalyzers, hearing aid test instruments, or other audio systems utilizing a microphone for input signals, may be calibrated with the QC-10 and QC-20.