AES New York 2009
Paper Session P20

P20 - Loudspeakers in Rooms

Monday, October 12, 10:30 am — 1:00 pm
Chair: Sunil Bharitkar, Audyssey Labs/USC - Los Angeles, CA, USA

P20-1 Investigation of Bonello Criteria for Use in Small Room AcousticsTodd Welti, Harman International - Northridge, CA, USA
The Bonello Criteria are a set of conditions that are an attempt to use rectangular room dimensions as a general predictor of room modal response quality. Though intuitively satisfying, and often used in room design, the Bonello Criteria make certain assumptions that are almost never met in listening rooms, and the approach has never been systematically validated. An investigation using a computer model and a large number of possible room dimensions was made to see if meeting the Bonello Criteria should result in improved low frequency acoustical responses. Overall, the Bonello Criteria correlates only weakly to the Variance of Spatial Average and there is no correlation to Mean Spatial Variance.
Convention Paper 7849 (Purchase now)

P20-2 Subwoofers in Rooms: Effect of Absorptive and Resonant Room StructuresJuha Backman, Nokia Corporation - Espoo, Finland
The room-loudspeaker interaction at low frequencies, where individual modes can be easily identified, needs careful consideration when flat response and controlled spatial distribution are desired. The methods for controlling low frequency response are loudspeaker placement, use of multiple subwoofers, use of absorptive materials, and specific to low-frequency acoustics, use of resonators. The effects of various types of resonators and absorptive surfaces are computed using FEM for single and multiple subwoofer configurations in symmetrical and asymmetrical rooms, indicating that taking both the symmetry of the mode to be controlled and the loudspeaker placement into account when placing the resonators and/or absorbers is needed for optimal results.
Convention Paper 7957 (Purchase now)

P20-3 In Situ Measurements of Acoustic Absorption Coefficients Using the Surface Pressure MethodScott Mallais, John Vanderkooy, University of Waterloo - Waterloo, Ontario, Canada
This paper revisits a method for determining the acoustic reflection factor by use of two pressure measurements: one at a surface under study and the other at a rigid surface in the same location of a room. The rigid surface is approximated in situ by placing a steel sheet in front of the surface under study. Measurements are made with and without the sheet at the same location. The ratio of these measurements is used to determine the acoustic reflection factor of the surface. The principle and limitations of this method are discussed, and experimental results will be given for a rigid surface, a resonant surface, and an absorptive surface, measured in different environments.
Convention Paper 7958 (Purchase now)

P20-4 The Challenge to Find the Optimum Radiation Pattern and Placement of Stereo Loudspeakers in a Room for the Creation of Phantom Sources and Simultaneous Masking of Real SourcesSiegfried Linkwitz, Linkwitz Lab - Corte Madera, CA, USA
Stereo sound reproduction relies upon the creation of an illusion. Ideally the two loudspeakers and the room disappear, leaving only a phantom acoustic scene to be listened to. The polar frequency response of a loudspeaker determines the angular distribution of room reflections and their spectral content. The placement of the loudspeakers relative to the room surfaces determines the initial delay of the reflections. Together they affect the formation of phantom sources. A proven loudspeaker and room configuration is proposed as starting point for listening tests to determine the optimum loudspeaker radiation pattern. It is an invitation to extend our understanding of the psychoacoustic processes that are involved with stereo listening in a room and to replace anecdotal with scientific evidence.
Convention Paper 7959 (Purchase now)

P20-5 The Subjective and Objective Evaluation of Room Correction ProductsSean E. Olive, John Jackson, Allan Devantier, David Hunt, Harman International - Northridge, CA, USA
A panel of eight trained listeners gave comparative ratings for five different room correction products based on overall preference and spectral balance. The same loudspeaker/subwoofer without correction was included as a hidden anchor. The results show significant differences among the room correction products in terms of listener preference and perceived spectral balance. The subjective ratings are largely explained by a combination of anechoic and in-room frequency response measurements made on the combined acoustic response of the room correction/loudspeaker.
Convention Paper 7960 (Purchase now)