Quiet Cars could pose danger for my son

http://news.yahoo.com/s/ap/20100704/ap_on_bi_ge/us_quiet_hybrids

I have always been concerned about my son's safety walking to and from school, but now that he is no longer allowed to cross major intersections alone, I understand why. His central distance vision is distorted and messages take longer to get from his eye to the brain, decreasing his reaction time. This article illustrates how sound (or the lack thereof) may further hinder his future mobility. I agree with the idea that all silent vehicles should be required to have the SAME type of warning sound so that they are easily identifiable and won't get lost in the barrage of sounds that we hear every day. Even at that, there is still the risk that they will be ignored much like car alarms...Even I am guilty of that. I hear a car alarm and get annoyed rather than being alert. My son won't have that luxury one day...