Labels:anechoic chamber | shelf OCR: Noise Sound Transmission Loss ASTM E90- .99 Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss Building Partitions and Elements Sound Transmission Classification (STC The STC rating is calculated in accordance with ASTM test method -87 999 Standard Classification for Rating Sound Insulation. Free Field Noise Reduction Free Field Noise Reduction specified ir decibels and represents the louvers sound reduction open area Transmissior 1999 Reductior
