Indoor-outdoor method for measuring building noise reduction

Recent research has resulted in the development of a new SAE Recommended Practice (ARP 6973) for measuring building noise reduction in determining the eligibility of aircraft noise impacted structures for participation in FAA-funded Airport Sound Insulation Programs. The SAE ARP follows methods previously described in ASTM E966 by requiring an external loudspeaker and measurement of the difference between the exterior and interior noise levels, but has a special focus on aviation noise applications and provides detailed guidelines for practitioners working in the field. Like the methods described in ASTM E966, the SAE ARP 6973 method require the application of adjustment factors to the exterior noise level measurements to account for the reflection of sound energy from the façade surface. However, there are situations encountered in the field, such as areas with limited exterior space, where it is either difficult to place a loudspeaker, or to generate a uniform distribution of sound energy over the building facade. In an attempt to overcome these limitations, an alternative method for measuring noise reduction is described, where a loudspeaker is placed inside the house and the noise reduction measured from inside to outside, eliminating the need for any adjustments to the measured levels, and removing restrictions on the placement of an external loudspeaker.