I struck a nerve several years ago when I blogged about the horrible beep-beep noise made by heavy equipment when it backs up. Eventually a British company came up with a solution: a pulsed burst of white noise which is very evident when you are near the backing up vehicle but which disperses quickly so it doesn't travel and annoy people a mile away as the beeps do.

Now I am seeing more and more suggestions that electric cars, which run quite silently when slow, make some noise for safety. This is fine, but there are also suggestions that there will be music and vanity noises, like ringtones or "cartones." I can certainly see why this would appeal to people. (Already many think that their car is the place to play mind-numbing bass to announce musical taste to all others on the street.) There are even proposed laws.

While the cartones would be quieter than the backup beep or the heavy bass, I really fear that people will overdo what they think is the purpose -- being attention grabbing. They will want to distract, and that will create a cacophony on the roads. It's hard to make sounds that are meant to be attention grabbing (or vanity oriented) not travel beyond the range that you need them for safety.

I don't want to imagine what it might be like living as I do with a 3-way stop outside my window, with each car singing a different tune or strange noise every time it slows down and starts up again. Who will want to live near intersections or parking lots?

I have a few proposals:

1. Like the beep-beep solution, use white noise that just doesn't travel very far, but is easily noticed when close.
2. Use natural sounds, like waves crashing, birds chirping, wind blowing. We are tuned to hear those sounds in an otherwise silent environment, but our brains also can easily ignore them in background form.
3. Do indeed tune the volume based on ambient noise. This is suggested in the O'Reilly article linked above. They propose it to be loud enough. It should also be quiet enough.
4. Don't do it at a speed where the tires and wind and electric motors are making enough noise already.
5. As robocar sensors become more common, such as LIDAR and radar, only make the noise when there are people who might come in contact with the vehicle. Otherwise, be silent.
6. Since robocars will not hit people in any normal operation, even people who don't know they are there, such vehicles need not make any noise. HOwever, if they see a human or anything else on a collision course, let them make a more loud and useful noise that really gets attention, like a burst of white or pink noise, or even a horn if they ignore that. Start quiet, get louder if it is not reacted to in a human reaction time.

Let's not give up on this opportunity to return peace to our public spaces as electric cars and robocars become popular.