www.volpe.dot.gov/acoustics/
The John A. Volpe National Transportation Systems Center in Cambridge, Massachusetts, is an internationally recognized center of transportation and logistics expertise.

www.fhwa.dot.gov/environment/audible/index.htm
A Reprint of the Audible Landscape: A Manual for Highway Noise and Land Use.

widget.ecn.purdue.edu/~sqdh/
The Institute for Safe, Quiet, and Durable Highways (SQDH) is a joint effort between the Schools of Civil and Mechanical Engineering at Purdue University and the test facility and transportation research capabilities of the Pennsylvania Transportation Institute at the Pennsylvania State University.

www.inceusa.org
The International Institute of Noise Control Engineering (I-INCE) was founded in 1974. It is a worldwide consortium of organizations concerned with noise control, acoustics and vibration. The primary focus of the Institute is on unwanted sounds and on vibrations producing such sounds when transduced.