A new rating method for low-frequency impact noise

Abstract

Residents, building owners, architects and acoustic consultants are rightly concerned about footfall noise transmission through multi-family building floor/ceiling assemblies. By code, most projects in the USA are required to meet a minimum design rating of IIC 50; AIIC 45 if field tested. However, no matter how high the rating, residents in wood frame buildings often complain that low-frequency, or “thudding” footfall noise is a problem. Unfortunately, the IIC rating system does not evaluate impact noise at frequencies below 100 Hz. In this paper, we show that footfall noise is present at audible frequencies below 100 Hz, how this footfall noise can be replicated more objectively using ball drops or a tapping machine, and how measured impact noise might be used to develop a single number rating for low-frequency impact noise insulation of field tested floor/ceiling assemblies. The findings presented are not meant to be taken as final results, but rather a summary of progress made to-date for work that is under-development.Residents, building owners, architects and acoustic consultants are rightly concerned about footfall noise transmission through multi-family building floor/ceiling assemblies. By code, most projects in the USA are required to meet a minimum design rating of IIC 50; AIIC 45 if field tested. However, no matter how high the rating, residents in wood frame buildings often complain that low-frequency, or “thudding” footfall noise is a problem. Unfortunately, the IIC rating system does not evaluate impact noise at frequencies below 100 Hz. In this paper, we show that footfall noise is present at audible frequencies below 100 Hz, how this footfall noise can be replicated more objectively using ball drops or a tapping machine, and how measured impact noise might be used to develop a single number rating for low-frequency impact noise insulation of field tested floor/ceiling assemblies. The findings presented are not meant to be taken as final results, but rather a summary of progress made to-date for work that is...