Recently, there's been a lot of hue and cry about cars getting quieter - most specifically, from the advocates for the blind.
Now, this article, and the advocates, are absolutely undeserving of an Asshat of the Day, because they're not being idiots. It is a genuine concern. I think, however, that it is misplaced and possibly selfish.
Noise (particularly constant noise like traffic) is actively detrimental to the public health. It works against productivity. It's even been suggested that it increases the risk of heart attack.
The benefits to cutting traffic noise out of city life are substantial and self-evident... and, I think, outweigh the benefits to the vanishingly small proportion of the population who are blind. According to the CNIB, more than 50% of those individuals who are registered as legally blind in Canada were blinded by macular degeneration, glaucoma or cataracts - all conditions commonly found in the aged. This means individuals who would be poorly suited to avoid a car (even if they heard it coming), if the driver weren't aware.
And that's one other argument I have - dodging cars on the road should not be the responsibility of the blind. The onus should be (now and in the future) on the driver to be aware of those around them, sighted or no.
So I think that noise-making technology would defeat one of the more pleasant side-effects of the conversion to electric cars - peace and quiet in our cities. And I don't think it's worth it.