Comment by post-it
8 hours ago
The construction site next door is using those vehicles, and they're also a lot more pleasant throughout the day. It's easier to tune out white noise than beeping. The first cshh is a little louder than the others, which is a nice design touch.
Speak for yourself, I can tune out a steady beep much easier than the sound of a seagull being strangled to death. (That's what the ones around here sound like anyway.)
On a more serious note: the loud beeping backup alarms were DESIGNED to be annoying and difficult to miss. I would not be surprised in the least if a study showed these "less annoying" backup alarms correlating to a higher number of children being run over by reversing vehicles.
There have been studies and those resulted in the less annoying backup sounds. These sounds are essentially harsh white noise, which has one significant difference to the beeping: it's level drops off differently with distance, meaning you can blast it louder and people who are really in the wrong spot will notice better it means them, while people who are not meant will not be annoyed or fatigued by it. Two noise sources combine different than two tonal sources and the human ear can locate broadband sources better than single tones.
This was developed especially for use in backup heavy environments like harbors where workers started ignoring constant beeps.
There's also another difference: beeps can reflect coherently off of surfaces, causing directionality confusion in a dense environment. White noise is much less likely to have odd interference patterns, maximizing our ability to localize the sound.