| Main Title |
Techniques for the Measurement of Acoustic Impedance of Asphalt. |
| Author |
Mansbach, Peter A. ;
Holmer, Curtis I. ;
|
| CORP Author |
National Engineering Lab. (NBS), Washington, DC. Acoustical Engineering Div. ;Environmental Protection Agency, Washington, DC. Office of Noise Abatement and Control. |
| Year Published |
1978 |
| Report Number |
NBSIR-78-1541; NBS-2004457; |
| Stock Number |
PB-287 936 |
| Additional Subjects |
Flexible pavements ;
Acoustic impedence ;
Acoustic measuring instruments ;
Sound analyzers ;
Wind ;
Temperature gradients ;
Transportation noise ;
Noise pollution ;
Truck noise
|
| Holdings |
| Library |
Call Number |
Additional Info |
Location |
Last
Modified |
Checkout
Status |
| NTIS |
PB-287 936 |
Some EPA libraries have a fiche copy filed under the call number shown. |
|
07/26/2022 |
|
| Collation |
94p |
| Abstract |
Five techniques were used in an attempt to measure the very high acoustic impedance of an asphalt surface. These techniques are: Impedance Tube, Pure-Tone Traverse, Pulse-Echo, Broad-Band Cross-Correlation, and Direct Accelerometer Measurement. These techniques are described and evaluated in some detail, and the results of the measurements are presented. Of the five techniques, the broad-band cross-correlation proved to be the most effective, and also is capable of even further improvement. The value of the specific acoustic admittance of the sealed asphalt surface obtained with this technique is .007. The effects of wind and temperature gradients on ray propagation are derived theoretically, as well as spherical wavefront corrections to plane-wave reflection. These refinements are necessary to realize the full potential of the broad-band measurement technique. Effects of the finite test surface impedance on source emission measurements are discussed. Measurement uncertainties of the order of 1-2 dB due to surface impedance are considered likely. |
| Supplementary Notes |
Prepared for Environmental Protection Agency, Washington, DC. Office of Noise Abatement and Control. |
| NTIS Title Notes |
Final rept. Aug 76-Mar 77. |
| PUB Date Free Form |
Oct 78 |
| Category Codes |
13B; 20A; 50A; 68B; 86V |
| NTIS Prices |
PC A05/MF A01 |
| Primary Description |
200/02 |
| Document Type |
NT |
| Cataloging Source |
NTIS/MT |
| Control Number |
323751622 |
| Origin |
NTIS |
| Type |
CAT |
