Narrator: This is Science Today. Hybrid cars may be good for the environment, but studies have found they their quiet engines are harder to hear, posing a risk to blind pedestrians. Lawrence Rosenblum, a psychologist at the University of California, Riverside, says their findings may influence a congressional bill proposed to determine if cars should meet minimum audibility standards.
Rosenblum: Possibly new cars by the year 2010 might have some sort of sound if they are in fact hybrids or electrics - have some sort of sound that would play at very slow speeds and be a relatively quiet sound. So, maybe something that would click on from under the hood or from some other part of the car that the car could be audible. This is a fairly easy thing to take care of, technically. It is jut a question of doing it right so it doesn't add to problems of noise pollution and so that the sound is not distracting. And so that's one thing we're working on as well - is try to determine what type of sound would be most effective without being intrusive.
Narrator: For Science Today, I'm Larissa Branin.