[sidewndr46]

They have to be loud enough to be heard through hearing protection. The amplitude is a feature.

It's a "solved problem" in the sense that nuclear energy is a solved problem. There's no mandate to actually see widespread roll out of anything that may be a better solution.

There's a construction site near me at present. There is always 1 machine in reverse, at all times. The utility of having a backup beeper or any noise making device on that site is thus zero. It is the single largest source of noise pollution, larger than the roadway

[bumby]

>The utility of having a backup beeper or any noise making device on that site is thus zero.

This strikes me as an odd take, maybe from someone who has never worked on a construction site.

Our auditory sense is more than just a binary “present/not present” detection. We can sense distance and direction. Just because there is a backup beeper somewhere on site does not mean there is no value to any other auditory signal.

Think about when you’re in a congested city. There’s probably a lot of ambient car noise, including horns, in the background. That doesn’t mean you’re unable to react to a honking car in your immediate vicinity.

[sidewndr46]

You just believe you can sense the direction of loud noises in urban environments. Our nervous system has no "404 not found" for positional awareness. Even after severe head trauma, you have a sense of position for everything. It's so wrong as to be useless, but you have it.

Ask anyone who's been at a shooting in a city. Everyone gives a different answer for where the shooter was at. It's such a severe issue the US Army has microphone arrays they equip urban combat vehicles with. Even with bullets actually bouncing off the armor the troops cannot accurately locate the direction of the shooter(s).

[bumby]

As the other poster mentioned, the characteristics of sound matter. That’s why the report of a firearm is a bad example.

But there are more commonplace examples. Older phone ringtones are often hard for people to locate, but nearly everybody can pinpoint the sound of a dropped coin. Sound perception is more complex than just perception of pressure levels. To the point above, you wouldn’t confuse a car honking in front of you with one behind you even in the presence of ambiguous ambient noise.

[sidewndr46]

I'm not talking about the report of a firearm. I'm talking about the physical impact of the bullet on the armored vehicle you are in.

Also I have no idea what you mean by "but nearly everybody can pinpoint the sound of a dropped coin". What sound does a coin make when it is dropped on a busy street?

[tomn]

Bullets are a bad example because they have multiple properties which makes them much harder to localise than many other sounds.

I'm pretty sure most people can localise a vehicle emitting broadband noise (engine or white reversing sound) in the conditions that matter.

[tomn]

> They have to be loud enough to be heard through hearing protection.

It's kind of a nit-pick, but this is not really true.

Very approximately, you will perceive a sound if it is above your threshold of hearing, and also not masked by other sounds.

If you're wearing the best ear defenders which attenuate all sounds by about 30dB, and you assume your threshold of hearing is 10dBSPL (conservative), any sound above 40dBSPL is above the threshold of hearing. That's the level of a quiet conversation.

And because your ear defenders attenuate all sounds, masking is not really affected -- the sounds which would be masking the reversing beepers are also quieter.

There are nuances of course (hearing damage, and all the complicated effects that wearing ear defenders cause), but none of them are to the point that loud reversing noises are required because of hearing protection -- they are required to be heard over all the other loud noises on a construction site.

> The utility of having a backup beeper or any noise making device on that site is thus zero.

The inverse square law says otherwise; on site the distances will be much more apparent.