Effect of boundary diffusers in a reverberation chamber: standardized diffuse field quantifiers

Area of Science:

• Acoustics
• Architectural Acoustics
• Sound Field Analysis

Background:

• Reverberation chambers require high sound field diffusivity for accurate acoustic measurements.
• Hanging or rotating diffusers are commonly used but have limitations in achieving adequate diffusivity.
• Previous studies have noted issues with reproducibility and repeatability in diffusivity measurements.

Purpose of the Study:

• To systematically compare the effectiveness of hanging diffusers versus boundary diffusers in a 1:5 scale reverberation chamber.
• To analyze sound field diffusivity using quantifiers from established acoustic standards.
• To identify potential inconsistencies within these standards that may affect diffusivity characterization.

Main Methods:

• Utilized a 1:5 scale reverberation chamber for experimental analysis.
• Employed three quantifiers: maximum absorption coefficient, standard deviation of decay rate, and total confidence interval.
• Compared diffusion characteristics between hanging and boundary diffuser types.

Main Results:

• Boundary diffusers and hanging diffusers demonstrated comparable sound field diffusion.
• Analysis indicated inconsistencies among the ASTM E90, ASTM C423, and ISO 354 standards.
• These standard inconsistencies may contribute to documented issues in diffusivity measurement reproducibility.

Conclusions:

• Both boundary and hanging diffusers offer similar levels of sound field diffusion.
• Inconsistencies in acoustic measurement standards can complicate the assessment of sound field diffusivity.
• Further refinement of measurement standards is needed to improve the reliability of diffusivity characterization.