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Past attempts at developing a system able to quantify the sound reflectivity of a surface have been hindered by the shear difficulty of repeatability and reproducibility. Where and why these challenges arise, and how they can be overcome is discussed. Sound fields resulting from direct sound energy projected at various incident angles toward materials and assemblies are compared as well as how laboratory setups and specimen changeovers can affect outcomes. Can precision be increased and bias avoided? A proposed system based on software driven microprocessors and robotic precision is very fast with a high degree of precision performing at less than 0.1 mm error over 50 repeated runs. The performance in terms of repeatability and reproducibility are approximately equivalent to today's ink jet printers. As a recognized acoustic metric, the Sound Reflectivity Index could provide vital data that would accompany all products. For acousticians, a higher order of accuracy would be possible in designs involving en...

A review of the literature today concerning noise in hospitals, both public and peer review, points to a continual increase in noise complaints from medical staff and patients in hospitals. One would expect that things would be getting better by now, but this is not the case. Noise surveys that we have recently conducted suggest that though unsatisfactory conditions are widespread, a list of simple, cost effective solutions has proven to be effective. This paper presents an array of actual projects detailing the development of remedies for noise annoyance in hospitals in an effort to increase the comfort and performance of medical staff and patients.

A major part of room acoustics concerns sound control within a space. This traditionally involves reverberation control, music envelopment, optimization of speech comprehension and privacy, noise control, spatial enhancement, modal and reflection control for rooms used in recording, mixing, editing, mastering, and measuring sounds and hearing. In all of these examples, room acoustics is influenced by early reflections from the interior surfaces, objects and geometry. The impedance of a surface generally varies in relation to the incident angle of sound waves, therefore knowing the true reflectivity of surfaces would be complimentary to sound decay time and absorption coefficients. This presentation reviews current trends in the measurement of sound reflectivity as well as many of the challenges involved in developing an approved laboratory measurement methodology. Not only a potentially important tool for acousticians, architects and designers, but a formally adopted “Reflectivity Index” would aid product...

12 newly renovated classrooms have been studied to determine the accuracy of prediction software used to guide architects, acousticians and interior designers. Several variations in renovation techniques based on traditional precepts were compared. After the renovations were complete, measurements and recordings were made of speech, noise, and reverberation when the rooms were both occupied and nonoccupied by students. A systematic map of the results was compiled, which when presented on a seat by seat basis, defined values of merit for the presumed optimizations and were compared to the predicted values. The two principle indices chosen as targets were increases in total speech level and decreases in total noise level (including late reverberation). When referred to these targets, several novel strategies proved to offer higher value/cost ratios while a few traditional strategies proved to be deficient and in some cases detrimental to at least one of the principle indices. Emerging from this study is wha...

Recent literature suggests that some of today’s criteria for classroom acoustics might be in need of revision. This article explores the traditional acoustic classroom criteria as they are applied today, and why several of the design goals for construction or renovation of learning spaces might not be appropriate acoustic targets. The acknowledged quest for optimized acoustics for the enhancement of learning is discussed and related to a series of newer metrics for the measure and modeling of speech level, occupied and unoccupied noise, controlled reverberation, and SNR values presented on a seat‐by‐seat basis. Based on the measured results of classrooms designed and built in accordance to these newer metrics, our research indicates that these guidelines would incur an average increase of 2% to 8% to current budgets. Specifics involving building costs versus acoustic value are also discussed. Further, research involved in the evaluation of scholastic advantages is underway.