The Fenestration and Glazing Industry Alliance (FGIA) has released an updated AAMA TIR-A1, Acoustical Performance of Exterior Fenestration Products, providing technical guidance on sound transmission, measurement and noise-control strategies for glazing and fenestration systems.
The updated report clarifies the distinction between Sound Transmission Class (STC) and Outdoor-Indoor Transmission Class (OITC), including when each classification is appropriate for evaluating product acoustical performance. STC primarily addresses airborne sound transmission across a standardized frequency range, while OITC is intended to better represent exterior noise sources and lower-frequency sound, making it particularly relevant to façades exposed to traffic and other outdoor noise.
The document was last updated in 2015 and has now been consolidated with IGMA TM-6000 into a single reference covering fundamental acoustical principles and the factors that influence fenestration performance.
According to FGIA, the guide is intended for a broad technical audience, including fenestration designers working to meet architectural sound-control specifications and sales professionals explaining acoustic performance to customers. 
Source: FGIA with additional information added by Glass Balkan
