Field Evaluation of Reflected Noise from a Single Noise Barrier

TRB's National Cooperative Highway Research Program (NCHRP) Research Report 886: Field Evaluation of Reflected Noise from a Single Noise Barrier analyzes the characteristics of sound reflected from a noise barrier to the opposite side of a highway. State departments of transportation (DOTs) periodically receive complaints from residents about increases in traffic noise that residents believe are the result of noise reflected from a new noise barrier added across the roadway from them. Currently available analytical tools are limited in their ability to evaluate reflected noise and some of the subtle changes in the quality of sound that can occur when it is reflected. Therefore, it is a challenge for DOTs to determine conclusively if complaints about reflected noise are the result of actual or perceived changes in noise characteristics, and to identify locations where absorptive surface treatments could be beneficial.

The study compares reflected noise from sound-reflecting barriers and from barriers with a sound-absorptive surface. It examines both the levels and frequencies of reflected noise to better understand how reflected noise is experienced by communities.

The full report, which includes four detailed appendices, is 27 MB and may take time to download. It is accompanied by several appendices, a tool, and a guide:

• Appendix D: Using the Barrier Reflections Screening Tool
• Appendix E: Phase 1 (Sound-Reflecting Barriers)—Detailed Protocols and Results
• Appendix F: Photographs, Phase 1 (Sound-Reflecting Barriers) Measurement Sites
• Appendix G: Photographs, Phase 2 (Sound-Absorbing Barriers) Measurement Sites
• Barrier Reflections Screening Tool
• Layperson Guide - "Reflected Sound from Highway Noise Barriers" 

A presentation file that summarizes the research also is available on the report project page.