Acoustics of typical glass and concrete
Figure 2 lists the acoustic performance of typical glass and concrete building materials.
Curtain wall systems provide limited isolation from exterior noise sources. Typical performance is usually limited to about OITC 30. Interior retrofit systems or secondary inboard laminated glazing designs can increase curtain wall performance to greater than OITC 35.
It is always important to also consider roof construction, particularly when the interior space of interest is directly below the roof deck. When train noise and aircraft flyovers are a major concern, a concrete roof deck with a resiliently supported secondary, insulated, two-layer gypsum board ceiling is generally required.
Where frame construction is utilized in areas near significant noise sources, insulated laminated glass windows and multi-layer insulated gypsum board interior wall construction—decoupled from the exterior framing—can be utilized to reduce transfer of exterior sound.
Conclusion
Designing sound-sensitive buildings in the vicinity of exterior noise sources requires attention to many important details, starting with a thorough understanding of required maximum interior background noise levels. Although each design must be considered individually, when building near airports and railway lines, access to FAA Ldn contour maps and onsite noise studies should be reviewed in order to understand the environmental noise level of the new building site.
Design requirements in excess of OITC 40 are not uncommon in these areas, which, in addition to suitable exterior wall and glazing, will also typically require heavy roof construction in order to meet all of the acoustics expectations of the new occupants.
Terence Tyson, PE, CDT, is a principal consultant in acoustics at Acentech, a multi-disciplinary acoustics, audiovisual systems design, and vibration consulting firm. Much of his work has involved collaborating with mechanical and electrical engineers on the control of noise from HVAC and other mechanical and electrical systems in sound-critical facilities such as concert halls, performing arts centers, and recording studios. Tyson is a member of the Institute of Noise Control Engineering (INCE), American Society of Mechanical Engineers (ASME), and American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE). He can be reached at ttyson@acentech.com.
