Clarke Ii Berdan

A jury study of noise isolation between condo units incorporating QuietZone® acoustic wall framing in the common wall

Two identical side‐by‐side two‐story condo units with basements were built in the newly built Owens Corning Building Science and Innovation Center. These units incorporated modern features such as multistory great rooms with adjoining kitchens. Home offices, bedrooms, and basements were located on opposite sides of the common wall. It is common practice to use double‐stud walls between adjacent units in multifamily construction. It is also good practice to have a noncontiguous floor plate between units. Instead of a double‐stud wall, these units incorporated QuietZone■ acoustic wall framing (resilient stud), and other Owens Corning recommended noise control measures. The wall transmission loss characteristics were measured in the field and in the laboratory. A laboratory jury study was conducted to investigate the adequacy of perceived noise isolation between the units for various source and background noise types and levels.

Sound transmission class (STC) is not a good predictor of performance of insulated wood frame gypsum walls used as interior partitions in most North American homes

Home owners say that insulating interior walls improves the acoustic environment. Based on STC alone, no perceptible difference is expected. To define ‘‘improved,’’ ethnographic and laboratory studies were conducted. Ethnographic studies in 33 homes, revealed owners want quieter, less reverberant environments, including rooms where added isolation is desired. Families lives are 24/7, leading to frustration that they cannot use their homes without disturbing others. Laboratory jury studies were conducted where 35 listeners rated the relative isolation of insulated and uninsulated walls. Noise sources included broadband and real home noises. Insulated walls were perceived to perform better than uninsulated walls in all cases. Noise control engineers know that STC is only a quick screening tool (actual sound transmission loss should be used to estimate noise reduction between rooms). This is what the jurors appeared to sense. Jury ratings and the midfrequency average SPL correlated reasonably well. The STC is determined by a structural resonance near 125 Hz. Above this band, insulation has a significant impact on transmission loss (perceptible, 6 dB average). A new rating system is needed that quantifies what actual listeners hear in quiet room environments. A model using some form of room criteria is suggested.