AES San Francisco 2008
Paper Session P4
Thursday, October 2, 2:30 pm — 4:30 pmP4 - Acoustic Modeling and Simulation
Chair: Scott Norcross, Communications Research Centre - Ottawa, Ontario, Canada
P4-1 Application of Multichannel Impulse Response Measurement to Automotive Audio—Michael Strauß, Fraunhofer Institute for Digital Media Technology - Ilmenau, Germany, and Technical University of Delft, Delft, The Netherlands; Diemer de Vries, Technical University of Delft - Delft, The Netherlands
Audio reproduction in small enclosures holds a couple of differences in comparison to conventional room acoustics. Today’s car audio systems meet sophisticated expectations but still the automotive listening environment delivers critical acoustic properties. During the design of such an audio system it is helpful to gain insight into the temporal and spatial distribution of the acoustic field's properties. Because room acoustic modeling software reaches its limits the use of acoustic imaging methods can be seen as a promising approach. This paper describes the application of wave field analysis based on a multichannel impulse response measurement in an automotive use case. Besides a suitable preparation of the theoretical aspects, the analysis method is used to investigate the acoustic wave field inside a car cabin.
Convention Paper 7521 (Purchase now)
P4-2 Multichannel Low Frequency Room Simulation with Properly Modeled Source Terms—Multiple Equalization Comparison—Ryan J. Matheson, University of Waterloo - Waterloo, Ontario, Canada
At low frequencies unwanted room resonances in regular-sized rectangular listening rooms cause problems. Various methods for reducing these resonances are available including some multichannel methods. Thus with introduction of setups like 5.1 surround into home theater systems there are now more options available to perform active resonance control using the existing loudspeaker array. We focus primarily on comparing, separately, each step of loudspeaker placement and its effects on the response in the room as well as the effect of adding additional symmetrically placed loudspeakers in the rear to cancel out any additional room resonances. The comparison is done by use of a Finite Difference Time Domain (FDTD) simulator with focus on properly modeling a source in the simulation. A discussion about the ability of a standard 5.1 setup to utilize a multichannel equalization technique (without adding additional loudspeakers to the setup) and a modal equalization technique is later discussed.
Convention Paper 7522 (Purchase now)
P4-3 A Super-Wide-Range Microphone with Cardioid Directivity—Kazuho Ono, Takehiro Sugimoto, Akio Ando, NHK Science and Technical Research Laboratories - Tokyo, Japan; Tomohiro Nomura, Yutaka Chiba, Keishi Imanaga, Sanken Microphone Co. Ltd. - Japan
This paper describes a super-wide-range microphone with cardioid directivity, which covers the frequency range up to 100 kHz. The authors have successfully developed the omni-directional microphone capable of picking up sounds of up to 100 kHz with low noise. The proposed microphone uses an omni-directional capsule adopted in the omni-directional super-wide-range microphone and a bi-directional capsule that is newly designed to fit the characteristics of the omni-directional one. The output signals of both capsules are synthesized as the output signals to achieve cardioid directivity. The measurement results show that the proposed microphone achieves wide frequency range up to 100 kHz, as well as low noise characteristics and excellent cardioid directivity.
Convention Paper 7523 (Purchase now)
P4-4 Methods and Limitations of Line Source Simulation—Stefan Feistel, Ahnert Feistel Media Group - Berlin, Germany; Ambrose Thompson, Martin Audio - High Wycombe, Bucks, UK; Wolfgang Ahnert, Ahnert Feistel Media Group - Berlin, Germany
Although line array systems are in widespread use today, investigations of the requirements and methods for accurate modeling of line sources are scarce. In previous publications the concept of the Generic Loudspeaker Library (GLL) was introduced. We show that on the basis of directional elementary sources with complex directivity data finite line sources can be simulated in a simple, general, and precise manner. We derive measurement requirements and discuss the limitations of this model. Additionally, we present a second step of refinement, namely the use of different directivity data for cabinets of identical type based on their position in the array. All models are validated by measurements. We compare the approach presented with other proposed solutions.
Convention Paper 7524 (Purchase now)