Panel Options Sound Transmission Loss Data, dB Click below for specifications and drawings Octave Band Center Frequency, Hz 125 250 500 1K 2K 4K STC Barrier Panels               TYPE SL 18 26 35 45 49 52 37 TYPE SL-R 18 26 35 45 49 52 37 H/P 42 V-Stack 23 31 40 49 56 62 42 H/P 38 24 25 33 43 50 55 38 H/P 42 23 31 40 49 56 62 42 H/P 44 27 34 41 46 53 59 44 H/H 50 26 44 50 54 57 64 50 H/H 52 37 43 47 53 54 57 52 All tests performed by Riverbank Acoustical Laboratories, an independent NVLAP accredited acoustical testing facility. The test method conforms with ASTM Designations E90-99 or E90-02 and E413-87. Octave Band Center Frequency, Hz 125 250 500 1K 2K 4K STC Sound Absorption Coefficients Barrier Panels Click below for specifications and drawings               TYPE SL 0.92 1.15 1.22 1.13 1.08 1.04 0.95 (1.15) H/P 42 0.68 1.06 1.12 1.08 1.03 0.98 0.95 (1.05) All tests performed by Riverbank Acoustical Laboratories, an independent NVLAP accredited acoustical testing facility. The test method conforms with the requirements of the ASTM Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method: ASTM C423-90a and E795-00.