Evaluation of Two Alternative Procedures for Measuring Airflow Resistance of Sound Absorbing Materials

It is well known that sound absorption and sound transmission properties of open porous materials are highly dependent on their airflow resistance values. Low values of airflow resistance indicate little resistance for air streaming through the porous material and high values are a sign that most of the pores inside the material are closed. The laboratory procedures for measuring airflow resistance have been stan- dardized by several organizations, including ISO and ASTM for both alternate flow and continuous flow. However, practical implementation of these standardized methods could be both complex and expensive. In this work, two indirect alternative measurement procedures were compared against the alternate flow standardized technique. The techniques were tested using three families of eco-friendly sound absorbent materials: recycled polyurethane foams, coconut natural fibres, and recycled polyester fibres. It is found that the values of airflow resistance measured using both alternative methods are very similar. There is also a good correlation between the values obtained through alternative and standardized methods.

National Driver Register (NDR) alternative program cost evaluation. Part II. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Evaluation of urethane snow plow blades as an alternative to rubber blades. Final report.

Virginia Department of Transportation, Richmond

Passenger vehicle, light truck and van convex mirror optimization and evaluation studies. Volume 2: evaluation of alternative mirror configurations. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Effectiveness of alternative skid reduction measures. Volume I: evaluation of accident rate-skid number relationships. Final report.

Federal Highway Administration, Office of Research and Development, Washington, D.C.

Evaluation of alternative waste treatment facilities /

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Application of radiochemistry techniques in food processing research : radioisotopic tracer techniques in evaluation and improvement of industry practices for removal of pesticide residues from foods : annual report no. 4 /

"D-1548."

Application of radiochemistry techniques in food processing research : radioisotopic tracer techniques in evaluation and improvement of industry practices for removal of pesticide residues from foods : annual report /

"TID-4500."

Application of radiochemistry techniques in food processing research : radioisotopic tracer techniques in evaluation and improvement of industry practices for removal of pesticide residues from foods /

Report prepared by project team and edited by Walter A. Mercer.

Evaluation of noise control technology and alternative noise certification procedures for propeller-driven small airplanes /

Mode of access: Internet.

National evaluation of the Special Supplemental Food Program for Women, Infants and Children (WIC), 1982-1985 : Documentation /

Cover title: The National WIC evaluation.

Dietary evaluation of food used in households in the United States /

Mode of access: Internet.