Field measurements of the airborne sound attenuation of installed building façades, exterior walls, windows and doors in accordance with ASTM E966.
On-Site Acoustic Testing performs field testing of building façades and façade elements where the objective is to determine how much outdoor sound is attenuated by the installed construction. Typical test elements include exterior wall assemblies, windows, glazed systems and doors.
ASTM E966 Field Testing
ASTM E966 provides field procedures for measuring outdoor-indoor noise reduction and, under appropriate test conditions, outdoor-indoor or apparent outdoor-indoor transmission loss. Unlike laboratory testing of an isolated specimen, E966 evaluates installed construction under field conditions.
The appropriate measurement method and reported result depend on the façade geometry, test element, outdoor sound field and project objective. Testing may use a controlled loudspeaker source or, for appropriate outdoor-indoor noise-reduction measurements, an existing transportation-noise source.
OITC, AOITC and OINIC
ASTM E966 measurements can be used with ASTM E1332 to develop single-number ratings describing the outdoor-to-indoor acoustical performance of a façade or façade element. Depending on the measurement conditions and method, these can include:
- OITC / FOITC – Outdoor-Indoor Transmission Class, including the field rating derived from outdoor-indoor transmission-loss measurements.
- AOITC – Apparent Outdoor-Indoor Transmission Class, derived from apparent outdoor-indoor transmission-loss measurements where field conditions and flanking paths are included in the measured result.
- OINIC – Outdoor-Indoor Noise Isolation Class, derived from outdoor-indoor noise-reduction measurements and representing the isolation of the receiving space from the specified outdoor sound field.
These ratings are not interchangeable. The appropriate metric is selected according to the project requirements, test geometry and the field conditions that can be established at the site.
OITC Rating Charts and Installed Façade Performance
Outdoor-Indoor Transmission Class (OITC) is a single-number rating used to describe attenuation of outdoor noise, including transportation noise. Published OITC ratings for glazing and walls can inform product selection but do not establish the performance of an installed façade. ASTM E966 field measurements may support FOITC, AOITC or OINIC ratings depending on the measurement method and site conditions.
When reading an OITC rating chart, check whether the numbers describe laboratory specimens or installed construction, whether the same rating procedure was used, and whether the assemblies are comparable. Higher values generally indicate greater attenuation under the specified rating procedure, but the chart cannot account for every installation defect, leakage path or site-specific noise source. OSAT can measure actual field performance. See commercial acoustics testing for related services.
For an explanation of product ratings, frequency weighting and comparisons, read our OITC rating chart and field testing guide.
Windows, Doors and Complete Façades
Field testing can be useful for verifying installed window and door systems, evaluating exterior wall assemblies, investigating unexpected interior noise, documenting completed construction and comparing measured performance with project criteria. Where an individual façade element is being evaluated, the surrounding construction must provide suitable conditions for a meaningful measurement.
Because incidence angle, flanking transmission and the configuration of the exposed façade can affect field results, OSAT documents the test conditions and selects the E966 procedure appropriate to the installation and the information required by the project.
Testing Elevated Façade Assemblies
OSAT also has battery-powered test equipment that can be operated from a manlift or scaffold when measurements are required at elevated wall, window or façade assemblies. This allows test equipment to be positioned at higher building elevations where practical access is available, rather than limiting field measurements to assemblies accessible from grade.
Related Building Acoustics Testing
- Building acoustics testing – ASTC, AIIC, OITC and reverberation time
- ASTC airborne sound isolation testing
- AIIC impact sound testing
- Building plan review for acoustical performance
Discuss Your Façade Testing Requirements
Contact On-Site Acoustic Testing to discuss the building element, project criteria, site conditions and the ASTM E966 measurement or rating required.
