AES Show: Make the Right Connections Audio Engineering Society

AES San Francisco 2008
Poster Session P17

Saturday, October 4, 11:30 am — 1:00 pm

P17 - Loudspeakers—Part 2

P17-1 Accuracy Issues in Finite Element Simulation of LoudspeakersPatrick Macey, PACSYS Limited - Nottingham, UK
Finite element-based software for simulating loudspeakers has been around for some time but is being used more widely now, due to improved solver functionality, faster hardware, and improvements in links to CAD software and other preprocessing improvements. The analyst has choices to make in what techniques to employ, what approximations might be made, and how much detail to model.
Convention Paper 7600 (Purchase now)

P17-2 Nonlinear Loudspeaker Unit ModelingBo Rohde Pedersen, Aalborg University - Esbjerg, Denmark; Finn T. Agerkvist, Technical University Denmark - Lyngby, Denmark
Simulations of a 6½-inch loudspeaker unit are performed and compared with a displacement measurement. The nonlinear loudspeaker model is based on the major nonlinear functions and expanded with time-varying suspension behavior and flux modulation. The results are presented with FFT plots of three frequencies and different displacement levels. The model errors are discussed and analyzed including a test with a loudspeaker unit where the diaphragm is removed.
Convention Paper 7601 (Purchase now)

P17-3 An Optimized Pair-Wise Constant Power Panning Algorithm for Stable Lateral Sound Imagery in the 5.1 Reproduction SystemSungyoung Kim, Yamaha Corporation - Shizuoka, Japan, and McGill University, Montreal, Quebec, Canada; Masahiro Ikeda, Akio Takahashi, Yamaha Corporation - Shizuoka, Japan
Auditory image control in the 5.1 reproduction system has been a challenge due to the arrangement of loudspeakers, especially in the lateral region. To suppress typical artifacts in a pair-wise constant power algorithm, a new gain ratio between the Left and Left Surround channel has been experimentally determined. Listeners were asked to estimate the gain ratio between two loudspeakers for seven lateral positions so as to set the direction of the sound source. From these gain ratios, a polynomial function was derived in order to parametrically represent a gain ratio in an arbitrary direction. The result of validating the experiments showed that the new function produced stable auditory imagery in the lateral region.
Convention Paper 7602 (Purchase now)

P17-4 The Use of Delay Control for Stereophonic Audio Rendering Based on VBAPDongil Hyun, Tacksung Choi, Daehee Youn, Yonsei University - Seoul, Korea; Seokpil Lee, Broadcasting-Communication Convergence Research Center KETI - Seongnam, Korea; Youngcheol Park, Yonsei University - Wonju, Korea
This paper proposes a new panning method that can enhance the performance of the stereophonic audio rendering system based on VBAP. The proposed system introduces a delay control to enhance the performance of the VBAP. Sample delaying is used to reduce the energy cancellation due to out-of-phase. Preliminary simulations and measurements are conducted to verify the controllability of ILD by delay control between stereophonic loudspeakers. By simulating ILD by the delay control, spatial direction at frequencies where energy cancellation occurred could be perceived more stable than the conventional VBAP. The performance of the proposed system is also verified by a subjective listening test.
Convention Paper 7603 (Purchase now)

P17-5 Ambience Sound Recording Utilizing Dual MS (Mid-Side) Microphone Systems Based upon Frequency Dependent Spatial Cross Correlation (FSCC)—Part-2: Acquisition of On-Stage SoundsTeruo Muraoka Takahiro Miura, Tohru Ifukube, University of Tokyo - Tokyo, Japan
In musical sound recording, a forest of microphones is commonly observed. It is for good sound localization and favorable ambience, however, the forest is desired to be sparse for less laborious setting up and mixing. For this purpose the authors studied sound-image representation of stereophonic microphone arrangements utilizing Frequency Dependent Spatial Cross Correlation (FSCC), which is a cross correlation of two microphone’s outputs. The authors first examined FSCCs of typical microphone arrangements for acquisition of ambient sounds and concluded that the MS (Mid-Side) microphone system with setting directional azimuth at 132-degrees is the best. The authors also studied conditions of on-stage sounds acquisition and found that the FSCC of a co-axial type microphone takes the constant value of +1, which is advantageous for stable sound localization. Thus the authors further compared additional sound acquisition characteristics of the MS system (setting directional azimuth at 120-degrees) and the XY system. We found the former to be superior. Finally, the author proposed dual MS microphone systems. One is for on-stage sound acquisition set directional azimuth at 120-degrees and the other is for ambient sound acquisition set directional azimuth at 132-degrees.
Convention Paper 7604 (Purchase now)

P17-6 Ambisonic Loudspeaker ArraysEric Benjamin, Dolby Laboratories - San Francisco, CA, USA
The Ambisonic system is one of very few surround sound systems that offers the promise of reproducing full three-dimensional (periphonic) audio. It can be shown that arrays configured as regular polyhedra can allow the recreation of an accurate sound field at the center of the array. But the regular polyhedric shape can be impractical for real everyday usage because the requirement that the listener have his head located at the center of the array forces the location of the lower loudspeakers to be beneath the floor, or even the location of a loudspeaker directly beneath the listener. This is obviously impracticable, especially in domestic applications. Likewise, it is typically the case that the width of the array is larger than can be accommodated within the room boundaries. The infeasibility of such arrays is a primary reason why they have not been more widely deployed. The intent of this paper is to explore the efficacy of alternative array shapes for both horizontal and periphonic reproduction.
Convention Paper 7605 (Purchase now)

P17-7 Optimum Placement for Small Desktop/PC LoudspeakersVladimir Filevski, Audio Expert DOO - Skopje, Macedonia
A desktop/PC loudspeaker usually stands on a desk, so the direct sound from the loudspeaker interferes with the reflected sound from the desk. On the desk, a "perfect" loudspeaker with flat anechoic frequency response will not give a flat, but a comb-like resultant frequency response. Here is presented one simple and inexpensive solution to this problem—a small, conventional loudspeaker is placed on a holder. The holder is a horizontal pivoting telescopic arm that enables easy positioning of the loudspeaker. With one side, the arm is attached on the top corner of the PC monitor, and the other side is attached to the loudspeaker. The listener extends and rotates the arm in horizontal plane to such a position that no reflection from the desk or from the PC monitor reaches the listener, thus preserving the presumably flat anechoic frequency response of the loudspeaker.
Convention Paper 7606 (Purchase now)