... -sound pressure level (S type) FEATURES 1. Meetthe standard of IEC 60942 2. Two types: Multi-frequency (F ... , 500Hz, 250Hz, 125Hz1000Hz1 000Hz, 500Hz, 250Hz, 125HzStandard deviation for FrequencySmaller than ±1 %Distortion(THD)≤1 %Power Supplylithium ... interface Nominal sound pressure level and frequency, environmental temperature, relative humidity, atmospheric pressure, wind speed (optional), clock ...