Jacob Klos, left, a Purdue graduate student in mechanical engineering, and Bob Bernhard, an engineering professor and director of the university's Institute of Safe, Quiet and Durable Highways, use a laser to study how noise is generated by a smooth tire on a textured surface. The tire, painted white to better reflect laser light, is rotated on a motor-driven roller. The laser measures vibration, and the data are relayed to a "signal analyzer" for interpretation.(Purdue News Service Photo by David Umberger)