AES Paris 2016
Poster Session P8
P8 - Room Acoustics, Instrumentation and Measurement
Sunday, June 5, 09:00 — 11:00 (Foyer)
P8-1 Numerical Modeling of Sound Intensity Distributions around Acoustic Transducer—Adam Kurowski, Gdansk University of Technology - Gdansk, Poland; Józef Kotus, Gdansk University of Technology - Gdansk, Poland; Bozena Kostek, Gdansk University of Technology - Gdansk, Poland; Audio Acoustics Lab.; Andrzej Czyzewski, Gdansk University of Technology - Gdansk, Poland
The aim of this research study is to measure, simulate, and compare sound intensity distribution generated by the acoustic transducers of the loudspeaker. The comparison of the gathered data allows for validating the numerical model of the acoustic radiation. An accurate model of a sound source is necessary in mathematical modeling of the sound field distribution near the scattering obstacles. An example of such obstacle is a human head. Preparation of a robust mathematical model of the sound field generated by a loudspeaker is one of the important factors in simulation of sound waves scattering by the human head. The numerical model is developed for the purpose of this kind of research.
Convention Paper 9525 (Purchase now)
P8-2 Small-Rooms Dedicated to Music: From Room Response Analysis to Acoustic Design—Lorenzo Rizzi, Suono e Vita - Acoustic Engineering - Lecco, Italy; Gabriele Ghelfi, Suono e Vita - Acoustic Engineering - Lecco, Italy; Maurizio Santini, Università degli Studi di Bergamo - Bergamo, Italy
Reviewing elements of on-field professional experience gained by the authors in the analysis of small-rooms dedicated to music, case studies offered by the everyday working practice allow to deal with specific situations, these are seldom described by usual theoretical models and literature. Using the analysis procedure developed and refined by authors, it is possible to investigate the characteristics of the acoustic response of the small-rooms with more detail. In this paper case studies of particular interest will be described: different small-room phenomena will be shown in the reported measurements.
Also a lecture—see Session P4-1]
Convention Paper 9502 (Purchase now)
P8-3 Electronic Shell—Improvement of Room Acoustics without Orchestra Shell Utilizing Active Field Control—Takayuki Watanabe, Yamaha Corp. - Hamamatsu, Shizuoka, Japan; Hideo Miyazaki, Yamaha Corp. - Hamamatsu, Shizuoka, Japan; Masahiro Ikeda, Yamaha Corporation - Hamamatsu, Shizuoka, Japan
This paper introduces an example of Electronic Shell acoustic enhancement system that was installed in a multi-purpose hall without an orchestra shell. The system is based on the concept of Active Field Control using electroacoustic means. The three objectives of this system were (1) the enhancement of early reflection for performers, (2) the increase of the reverberation time and the total sound energy on stage, and (3) the enhancement of early reflection in the audience area. The application of this system showed an improvement of about 1 to 2 dB in STearly and more than 2 dB in G in the audience area, which is equivalent or better performance than simple mobile typed orchestra shell.
[Also a lecture—see session P4-3]
Convention Paper 9504 (Purchase now)
P8-4 A Novel Approach of Multichannel and Stereo Control Room Acoustic Treatment, Second Edition—Bogic Petrovic, MyRoom Acoustics - Belgrade, Serbia; Zorica Davidovic, MyRoom Acoustics - Belgrade, Serbia
This paper describes additional development and improvement for all walls and ceiling diffusers, a new principle for multichannel or stereo control room setup/treatment, as was originally published at the 129th AES Convention (Paper Number 8295). The main effort focused on lowering the price of treatment, optimization of LF absorption, simplification of diffuser construction, solution for long diffusers without periodic repetition of diffusive sequence, and increasing room decay. All of these procedures and design principles will be described and attached to this paper, including theoretical analysis and room acoustical measurements from some of the first control rooms built following this new and improved principle.
Convention Paper 9526 (Purchase now)
P8-5 Harmonic Distortion Measurement for Nonlinear System Identification—John Vanderkooy, University of Waterloo - Waterloo, ON, Canada; Sean Thomson, Bowers & Wilkins - Steyning, West Sussex, UK
In order to model nonlinearities in loudspeakers, accurate measurement of harmonic distortion is necessary with particular attention to the relative phases of fundamental and harmonics. This paper outlines several ways that logarithmic sweeps can be used to achieve this goal. It is shown that Novak’s redesign of the logsweep is not strictly necessary, if proper account is taken of the phase relationships of the various harmonics. We study several other types of sweeps and methods to extract precise harmonic amplitudes and phases, using tracking filter concepts. The paper also deals with measurement systems that may have fractional-sample delays between excitation, reference, and data channels. Such details are important for accurate phase characterization of transfer functions. An intermodulation example is given for which sweeps with a single instantaneous frequency are inadequate.
[Also a lecture—see session P3-3]
Convention Paper 9497 (Purchase now)
P8-6 Metrics for Constant Directivity—Rahulram Sridhar, Princeton University - Princeton, NJ, USA; Joseph G. Tylka, Princeton University - Princeton, NJ, USA; Edgar Choueiri, Princeton University - Princeton, NJ, USA
It is often desired that a transducer have a polar radiation pattern that is invariant with frequency, but there is currently no way of quantifying the extent to which a transducer possesses this quality (often called “constant directivity” or “controlled directivity”). To address the problem, commonly-accepted criteria are used to propose two definitions of constant directivity. The first, stricter definition, is that the polar radiation pattern of a transducer should be invariant over a specified frequency range, whereas the second definition is that the directivity factor (i.e., the ratio between the on-axis power spectrum and the average power spectrum over all directions), or index when expressed in dB, should be invariant with frequency. Furthermore, to quantify each criterion, five metrics are derived: (1) Fourier analysis of contour lines (i.e., lines of constant sensitivity over frequency and angle), (2) directional average of frequency response distortions, (3) distortion thresholding of polar responses, (4) standard deviation of directivity index, and (5) cross-correlation of polar responses. Measured polar radiation data for four loudspeakers are used to compute all five metrics that are then evaluated based on their ability to quantify constant directivity. Results show that all five metrics are able to quantify constant directivity according to the criterion on which each is based, while only two of them, metrics 4 and 5, are able to adequately quantify both proposed definitions of constant directivity.
[Also a lecture—see session P3-7]
Convention Paper 9501 (Purchase now)
P8-7 Modeling Non-Shoebox Shaped Rooms with the Mode Matching Method—Bjørn Kolbrek, Norwegian University of Science and Technology - Trondheim, Norway; U. Peter Svensson, NTNU - Trondheim, Norway
When a room is not shoebox shaped, usually no analytical expressions exist for the determination of resonance frequencies and mode shapes. One option is to employ the Finite Element Method (FEM). In this paper an alternative method, the Mode Matching Method (MMM), is used to compute the transfer function and sound field of a non-shoebox shaped room with rigid walls and is compared to an FEM solution. The two methods show excellent agreement.
Also a lecture—see session P4-5]
Convention Paper 9506 (Purchase now)
