We are requesting a Sound Transmission Class (STC) testing/measurement kit. The Field STC Measurement Kit was developed to address the needs of those conducting compliance testing on SCIF, Temporary S... We are requesting a Sound Transmission Class (STC) testing/measurement kit. The Field STC Measurement Kit was developed to address the needs of those conducting compliance testing on SCIF, Temporary Secure Working Areas (TSWA), and similar type spaces that is required by Intelligence Community Directive (ICD) 705 Sound Group 3/STC 45 and Sound Group 4/STC 50.