Rosenblum: Folks at the National Federation of the Blind had been in contact with me because they've been concerned about the audibility of hybrid cars. Without that sound the blind in particular often have trouble judging the presence and position and speed of cars.
Narrator: Rosenblum found that hybrid cars approaching at a slow speed were virtually inaudible until they were just seven feet away - leaving a pedestrian only one second to react.
Rosenblum: There's currently a Congressional bill that's been proposed to determine whether maybe having minimum audibility for cars would be a good idea to institute in the next two to four years.
Narrator: For Science Today, I'm Larissa Branin.