Harry Alter

New home buyer noise reduction listening study.

In 2007 Owens Corning Science Technology in Granville, Ohio built a comparative wall assembly listening facility called the Acoustic Research Experience Laboratory (AREL) Annex. Within this listening facility, approximately 100 perspective new home buyers were selected to listen and evaluate various sound clips when played through wall assemblies at varying levels of noise reduction. Jurors responded to perceptual and lifestyle questioning. The building of the AREL Annex and listening study results will be discussed.

The N number, a speech privacy metric for rating walls, revisited

In 1962, Cavanaugh, et al., published the results of research which lead to a single number rating system for speech privacy of walls referred to as the N number [‘‘Speech Privacy in Buildings,’’ J. Acoust. Soc. Am. 34, 475–492 (1962)]. The N number is derived from measured one‐third octave band transmission loss data weighted using factors signifying the relative contribution to the articulation index. When the N number is summed with factors for source room floor area, source room speech use, measured adjacent room background noise rating, and the privacy requirement, the N number correlated subjective reactions observed in case studies better than average wall transmission loss alone. Owens Corning, the sponsor of this research, published the N number along with sound transmission class (STC) for several years. With the emergence of regulation of speech privacy in health care facilities, the Health Insurance Portability and Accountability Act (HIPAA), it seemed reasonable to revisit the N number. This ...

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.

‘‘Sound’’ science and technical education for sixth graders: A practical approach

Following the renovation of the Granville Middle School Cafeteria in Granville, OH it was noticed by students and faculty that noise levels during lunch period had dramatically increased. As a result, speech became unintelligible and eating became both unenjoyable and uncomfortable. The resident sixth‐grade science teacher with the assistance of a local acoustical engineer saw the opportunity to teach the sixth‐grade science class about acoustics and to get the children directly involved in solving the school’s cafeteria noise problem. The class met on a weekly basis to learn about sound and its influences on the school environment. Ultimately, the students would build a single microphone impedance tube and test the sound absorption characteristics of various materials. From their investigation they would design and install an acoustical wall treatment system to reduce reverberant noise levels in the school’s cafeteria. Acoustical measurements of the cafeteria were taken before and after treatment to comp...