0
TECHNICAL PAPERS

Synthesis of Room Responses Using the Virtual Source Representation and the Comb-Nested Allpass Filters

[+] Author and Article Information
Mingsian R. Bai

Department of Mechanical Engineering, National Chiao-Tung University, 1001 Ta-Hsueh Road, Hsin-Chu 300, Taiwan, R.O.C.msbai@mail.nctu.edu.tw

Kwuen-Yieng Ou

Department of Mechanical Engineering, National Chiao-Tung University, 1001 Ta-Hsueh Road, Hsin-Chu 300, Taiwan, R.O.C.

J. Vib. Acoust 128(6), 690-698 (Oct 09, 2005) (9 pages) doi:10.1115/1.2360951 History: Received October 13, 2004; Revised October 09, 2005

An artificial reverberator is proposed in this paper to synthesize room responses. The method employs the virtual source representation and the comb-nested allpass filters to generate the early reflection and late reverberation, respectively, of room responses. The virtual source method is based on a simple representation of sound field with a distribution of discrete simple sources on the boundary. The complex strengths of the virtual sources are then calculated by solving a frequency domain least-square problem. Parameters such as room geometry, size, and wall absorption are naturally incorporated into the synthesis process. The filtering property of human hearing is also exploited in a nonuniform sampling procedure to further simplify the computation. Apart from the early reflection, a comb-allpass filter network is adopted to simulate late reverberations. Optimal parameters of the comb-allpass filter network are obtained using the genetic algorithm (GA). The energy decay curve (EDC) is chosen as the objective function in the GA procedure. Numerical simulations are carried out for a rectangular room and a concert hall model to verify the proposed technique. Subjective listening experiments demonstrate that the present technique is capable of conferring remarkable realism of room responses.

FIGURES IN THIS ARTICLE
<>
Copyright © 2006 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Vertical view of virtual sources distributed in the neighborhood of the boundary of a rectangular room

Grahic Jump Location
Figure 2

Room response synthesis. (a) Block diagrams of the comb-allpass filter network. (b) Block diagram of the room response synthesis comprising the early reflection and the late reverberation modules.

Grahic Jump Location
Figure 3

Relationship between the cost function and the fitness function in GA

Grahic Jump Location
Figure 4

Flow chart of the GA optimization procedure

Grahic Jump Location
Figure 5

Comparison of frequency responses calculated using the virtual source representation, BEM; and the analytical solution of the rectangular room. (Solid line: analytical solution; dashed line: virtual source representation; circle line: BEM.)

Grahic Jump Location
Figure 6

Virtual sources distribution and the mesh for the Elmia Concert Hall. (a) 3D view. The inner and outer meshes correspond to the room boundary and the virtual source surface. (b) Vertical view.

Grahic Jump Location
Figure 7

Comparison of frequency responses calculated using the virtual source method and measured room response of the Elmia Concert Hall. (Solid line: A measured response; dashed line: virtual source method.)

Grahic Jump Location
Figure 8

Comparison of the EDCs resulted from the synthesized and the measured room responses with sample rate 44.1kHz. (Solid line: measured response; dashed line: virtual source method.)

Grahic Jump Location
Figure 9

Impulse responses of the Elmia hall with sample rate 44.1kHz. (a) Measured response. (b) Synthesized early reflection. (c) Synthesize total response including early reflection plus late reverberation.

Grahic Jump Location
Figure 10

Comparisons of the audio impression created using the synthesized response and the measured response. (a) Synthesized early reflection. (Solid line: synthesized early reflection; dashed line: measured response.) (b) Synthesized total response. (Solid line: synthesized total response; dashed line: measured response.) The labels on the horizontal axis are: RSI=room size impression, full=fullness, cla=clarity, nat=naturalness, live=liveness, and warm=warmth.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In