The location and orientation of a building can greatly impact the need for improved acoustical characteristics of the glass and glazing. Property located near flight paths or airport terminals, inner city locations near trains, subways, major intersections, harbor traffic or major road traffic are all easy examples to point out. Noise can be generated by a wide variety of sources which we hear at different frequencies represented by hertz (symbol: Hz) shown in Figure 1.

 Complete Acoustic Performance Tech Bulletin -
print version (PDF308 KB)

The characteristics of various components affect sound transmission. The most widely used glazing configurations for sound dampening include laminated glass with varied thickness of the interlayer and thickness of the glass. Including Warm-Light^® air spacer in the insulating glass can improve acoustical performance by reducing the transmission of exterior noise sources in the fenestration system.
Reviewing the glazing system components, including the air space material used in the insulating glass, can ensure overall sound transmission improvement.

Glazing variations affecting acoustics

• type of air spacer
• glass thickness (e.g. 1/8-in or 1/4-in) or inner and outer panes of dissimilar thickness in the insulating glass unit
• air space dimension (wider gaps or multiple gaps)
• dual glazing - triple glazing
• physical dimension of window (or glass)
• air infiltration
• glass type (annealed or laminated)

Building codes, along with building owners and architects are now specifying an Outdoor to Indoor Sound Transmission Class (OITC) rating number for the entire fenestration system, rather than for the individual acoustical fenestration components. Test reports and product performance data are available from the AZO/Tec technical department by » request

OITC rating summary:

• OITC is calculated in accordance with ASTM E1332 (Originally Published in 1990) over the frequency range of 80 to 4000 hertz.
• Created to provide a single number rating for facades (exterior walls) and facade elements (windows and doors) that are subjected to irritating noise levels. The higher the number, the higher the outdoor-indoor transmission loss.
• The OITC is calculated by subtracting the logarithmic summation of the transmission loss values from the logarithmic summation of the A-weighted transportation noise reference spectrum.
• The OITC rating can be assigned to specimens tested in the field and in the laboratory.