AES Vienna 2007: Paper Session P25

P25 - Room and Architectural Acoustics and Sound Reinforcement

Tuesday, May 8, 13:30 — 17:30

Chair: Franz Lechleitner, Austrian Academy of Sciences - Vienna, Austria

P25-1 50 Years of Sound Control Room Design—Jan Voetmann, DELTA Acoustics - Hørsholm, Denmark
Sound control room design is an interesting corner of small room acoustics and represents most of the problems found here: frequency balanced reverberation time, proper distribution of room modes, low frequency reproduction, sound source and receiver positioning, etc. The function of the control room is twofold, which is often overlooked. On one hand the control room together with the monitor loudspeakers should reproduce as faithfully as possible the efforts of the sound engineer and the producer in creating a new recording. On the other hand the control room should mimic the perceived acoustics of an average living room when checking the final result of the recording. Simply because most musical productions are aimed at the listening environment of a living room.
Convention Paper 7140 (Purchase now)

P25-2 Acoustics in Rock and Pop Music Halls—Niels W. Adelman-Larsen, Flex Acoustics - Lyngby, Denmark; Eric R. Thompson, Anders Christian Gade, Technical University of Denmark - Lyngby, Denmark
The existing body of literature regarding the acoustic design of concert halls has focused almost exclusively on classical music, although there are many more performances of rhythmic music, including rock and pop. Objective measurements were made of the acoustics of twenty rock music venues in Denmark and a questionnaire was used in a subjective assessment of those venues with professional rock musicians and sound engineers. Correlations between the measurements and the questionnaire answers lead, among others, to a recommendation for reverberation time as a function of hall volume. Since the bass frequency sounds are typically highly amplified, they play an important role in the subjective ratings, and the 63 Hz band must be included in objective measurements and recommendations.
Convention Paper 7141 (Purchase now)

P25-3 The Flexible Bass Absorber—Niels W. Adelman-Larsen, Flex Acoustics - Lyngby, Denmark; Eric. R. Thompson, Anders C. Gade, Technical University of Denmark - Lyngby, Denmark
Multipurpose concert halls face a dilemma. They host different performance types that require significantly different acoustic conditions in order to provide the best sound quality to both performers, sound engineers, and audience. Pop and rock music often contain high levels of bass sound energy but still require high definition for good sound quality. The mid- and high-frequency absorption is easily regulated, but adjusting the low-frequency absorption has typically been too expensive or requires too much space to be practical for multipurpose halls. A practical solution to the dilemma has been developed. Measurements were made on a variable and mobile low-frequency absorber. The paper presents the results of prototype sound absorption measurements as well as elements of the design.
Convention Paper 7142 (Purchase now)

P25-4 Improvements to Binary Amplitude Diffusers—Elizabeth Payne-Johnson, Gillian Gehring, University of Sheffield - Sheffield, South Yorkshire, UK; Jamie Angus, University of Salford - Salford, Greater Manchester, UK
Improved forms of diffusion structures based on absorption reflection gratings are presented. The theory, design, advantages, and limitations of these structures are discussed and their performance presented. Two methods of improving performance are suggested. The first structure is based on diffusion limited aggregation, which models non-regular fractal growth. The second structure was a panel with square absorption patches of a variable size that was determined by an m-sequence. Of the two, the second structure performed best. This paper demonstrates that improved diffusing structures that take up less space than phase reflecting ones are possible.
Convention Paper 7143 (Purchase now)

P25-5 An MLS Method for Non-Stationary and Outdoor Acoustic Paths—Jamie Angus, David Waddington, University of Salford - Salford, Greater Manchester, UK
The correlation properties of a directly carrier-modulated code sequence modulation signal are exploited to investigate sound propagation in turbulent air. An experiment is described in which the correlation properties of the spread spectrum signal are demonstrated and are used to calculate accurate times of flight that compare well with sonic anemometer measurements of speed of sound. The results illustrate that a directly carrier-modulated code sequence modulation system can provide significantly improved ways of measuring sound propagation outdoors. Moreover, the technique directly measures wind speed. This can be used to compensate the time of flight thus allowing the measurement of acoustic impulse responses in non-stationary media, for example outdoors, where reliable measurements have previously been difficult to obtain.
Convention Paper 7144 (Purchase now)

P25-6 Holographic Sound Field Analysis with a Scalable Spherical Microphone-Array—Anton Schlesinger, Delft University of Technology - Delft, The Netherlands; Giovanni Del Galdo, Jörg Lotze, Stephan Husung, Bernhard Albrecht, Technical University of Ilmenau - Ilmenau, Germany
Room acoustic parameters vary greatly with the position of the receiver and of the source, so that we cannot extract exhaustive information on the room acoustics from independent single-point measurements. Using array measurements permits the prediction of the sound field with a high spatial resolution and leads to a more precise assessment of the room acoustic properties. We propose an array technique to investigate room acoustics by reconstructing the volumetric sound field from measurements taken on the surface of a sphere, by means of the methods of nearfield acoustical holography (NAH). A virtual spherical single-microphone-array was constructed and successfully tested in room acoustical modal analysis.
Convention Paper 7145 (Purchase now)

P25-7 A Comparison of Modeling Techniques for Small Acoustic Spaces such as Car Cabins—Neil Harris, New Transducers Ltd. (NXT) - Huntingdon, Cambridgeshire, UK
This paper results from a case study comparing the relative cost effectiveness of three modeling techniques applied to a small acoustic space such as a car cabin. The techniques considered are finite element analysis, analytical solutions, and the quasi-analytical ray-trace or image method. A simple test-case is used to compare solution times and accuracy.
Convention Paper 7146 (Purchase now)

P25-8 Acoustical and Musical Design of the Sea Organ in Zadar—Ivan Stamac, Stims d.o.o. - Zagreb, Croatia
The Sea Organ in Zadar, Croatia, is an awarded urban architectural installation using sea wave random kinetic energy to produce quasi-musical sounds. It contains 35 flue pipes built into subterranean tunnels having outward-bound apertures for the sound to emanate. Each flue pipe is blown by a column of air pushed in turn by a column of moving water entering an immersed tube. The pipes are tuned to 9 tones of the diatonic major chords G and C6. The series of excited tones is a statistical function of time- and space-distributed wave energy to particular pipes. In this paper the acoustical and musical design propositions and solutions, as parts of the multidiscipline design process, will be presented.
Convention Paper 7147 (Purchase now)