A New Software Tool to Facilitate NURB Based Geometries in Acoustic Design

Abstract

Non-rational uniform B-splines (NURBs) are liberating acoustic design. Geometrical acoustics is no longer limited to flat surfaces. For decades, curved surfaces in computer models had to be broken down into a series of contiguous flat surfaces; a procedure prone to inaccuracy. With NURBs this is no longer the case. A new software tool has been developed by the authors, called NRAT, intended to facilitate acoustic design in NURB based geometries. Two parameters have been developed to quantify the efficiency of reflectors as they are being designed. They are called Reflector Efficiency (RFE) and Receiver Coverage (RCC). The two are quoted together, much like a blood pressure reading might be. The two parameters are required for reasons that became apparent to the authors as the NRAT tool was being developed. A small reflector, perhaps one that might be part of an array, may have a very high percentage of its surface area effectively casting reflections to the audience (perhaps 85%) but those reflections may only cover a small proportion of the audience area (say, 12%). Conversely, a large reflector, for example the side wall of a shoe box shaped concert hall, may only have a small area casting reflections to the audiencein our experience, in the range of 6%. But this small zone efficiently casts reflections across the expanse of the audience, sometimes as much as 90% or more. The quantification of the two RFE/RCC scenarios presented above would be, respectively, "85 over 12" and "6 over 90". Two case studies are presented.

Integration of Acoustics in Parametric Architectural Design

“…Acousticians, acting as consultants, have inevitably been introduced to these and many have seen some benefits in adopting the same language as their clients [1][2][3][4]. Although to each his/her interest and needs, for Marshall Day Acoustics, parametric tools do not aim at replacing the well-established and tested ray-tracing packages (Odeon, CATT, Matlab).…”

“…B Thomas Scelo tscelo@marshallday.com 1 Marshall Day Acoustics, Hong Kong SAR, China Plans, sections, rulers and sliding rules are perfect design tools as long as the architectural concept is wholly represented in 2 dimensions. Modern architecture often challenges this, and 3D computer packages are increasingly the only possible visualisation medium.…”

Building bridges between architectural acoustics and psychomusicology: A tribute to Leo Beranek—Centenarian scientist, inventor, and visionary.

“…David L. Klepper, primarily, and Russell Johnson, both of BBN, dealt with the day-to-day acoustical consultation. The hall itself was recently renovated, including acoustical changes, to accommodate an expansion by 200 seats (O’Keefe, Ashtiani, & Grant, 2013). The Calder-inspired reflectors have been removed and now serve another hall in the building.…”