• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Aug 2000

Volume 108, Issue 2, pp. 463-851

Return to All Sections
back to top
RSS Feeds

From a profiled diffuser to an optimized absorber

T. Wu, T. J. Cox, and Y. W. Lam

J. Acoust. Soc. Am. Volume 108, Issue 2, pp. 643-650 (2000); (8 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
The quadratic residue diffuser was originally designed for enhanced scattering. Subsequently, however, it has been found that these diffusers can also be designed to produce exceptional absorption. This paper looks into the absorption mechanism of the one-dimensional quadratic residue diffuser. A theory for enhanced absorption is presented. Corresponding experiments have also been done to verify the theory. The usefulness of a resistive layer at the well openings has been verified. A numerical optimization was performed to obtain a better depth sequence. The results clearly show that by arranging the depths of the wells properly in one period, the absorption is considerably better than that of a quadratic residue diffuser. © 2000 Acoustical Society of America.
Show PACS
43.55.Ev Sound absorption properties of materials: theory and measurement of sound absorption coefficients; acoustic impedance and admittance
43.55.Dt Sound absorption in enclosures: theory and measurement; use of absorption in offices, commercial and domestic spaces

On the combined effects of early- and late-arriving sound on spatial impression in concert halls

J. S. Bradley, R. D. Reich, and S. G. Norcross

J. Acoust. Soc. Am. Volume 108, Issue 2, pp. 651-661 (2000); (11 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
This paper describes six new experiments involving subjective ratings of the listener envelopment, LEV, and the apparent source width, ASW, of simulated sound fields. Previous work has identified LEV and ASW as the principal components of spatial impression in concert halls and has shown that ASW is primarily influenced by the level of early lateral reflections and LEV by late-arriving lateral reflections. The new results in this paper show that LEV can result from nonlateral late-arriving sounds and demonstrate the conflicting effects of early- and late-arriving lateral sound on ASW and LEV when both are present, as would occur in real halls. While it is possible to create simulated sound fields with only either LEV or ASW, in typical concert halls, the balance between early- and late-arriving lateral sound will determine the relative importance of LEV and ASW. LEV and ASW are shown to be perceived when the critical components of the sound field are salient relative to other components. The results of the new subjective studies were used to estimate expected ASW and LEV in 16 halls. In these halls LEV is predicted to be the stronger component of spatial impression. © 2000 Acoustical Society of America.
Show PACS
43.55.Hy Subjective effects in room acoustics, speech in rooms
43.66.Pn Binaural hearing
Return to All Sections
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close