LOGIN TO YOUR ACCOUNT

Username
Password
Remember Me
Or use your Academic/Social account:

CREATE AN ACCOUNT

Or use your Academic/Social account:

Congratulations!

You have just completed your registration at OpenAire.

Before you can login to the site, you will need to activate your account. An e-mail will be sent to you with the proper instructions.

Important!

Please note that this site is currently undergoing Beta testing.
Any new content you create is not guaranteed to be present to the final version of the site upon release.

Thank you for your patience,
OpenAire Dev Team.

Close This Message

CREATE AN ACCOUNT

Name:
Username:
Password:
Verify Password:
E-mail:
Verify E-mail:
*All Fields Are Required.
Please Verify You Are Human:
fbtwitterlinkedinvimeoflicker grey 14rssslideshare1
Languages: English
Types: Doctoral thesis
Subjects: other
The performance of reflectors and diffusers used in auditoria have been\ud evaluated both objectively and subjectively.\ud Two accurate systems have been developed to measure the scattering\ud from surfaces via the cross correlation function. These have been used to\ud measure the scattering from plane panels, curved panels and quadratic residue\ud diffusers (QRDs). The scattering measurements have been used to test\ud theoretical prediction methods based on the Helmholtz-Kirchhoff integral\ud equation. Accurate prediction methods were found for all surfaces tested. The\ud limitations of the more approximate methods have been defined. The\ud assumptions behind Schroeder's design of the QRD have been tested and the\ud local reacting admittance assumption found to be valid over a wide frequency\ud range. It was found that the QRD only produces uniform scattering at low\ud frequencies. For an on-axis source the scattering from a curved panel was as\ud good as from a QRD. For an oblique source the QRD produced much more\ud uniform scattering than the curved panel.\ud The subjective measurements evaluated the smallest perceivable change\ud in the early sound field, the part most influenced by reflectors and diffusers. A\ud natural sounding simulation of a concert hall field within an anechoic chamber\ud was used. Standard objective parameters were reasonable values when compared\ud to values found in real halls and subjective preference measurements. A\ud difference limen was measured for early lateral energy fraction (.048 ± .005); .\ud inter aural cross correlation (.075 ± .008); clarity index (.67 ± .13 dB); and\ud centre time (8.6 ± 1.6ms). It was found that; (i) when changes are made to\ud diffusers and reflectors, changes in spatial impression will usually be larger than\ud those in clarity; and (ii) acousticians can gain most by paying attention to lateral\ud sound in auditoria. It was also found that: (i) diffuse reflections in the early\ud sound field are not perceived differently from specular reflections; and (ii) the\ud initial time delay gap is not significant to listener preference.
  • No references.
  • No related research data.
  • No similar publications.

Share - Bookmark

Cite this article