When I worked with deaf people as relay operator, a question asked by a coworker during our orientation session on deaf culture was 'How do deaf people drive if they can't hear sirens from emergency vehicles?' The answer is that they rely on their other input to and have learned to compensate for their lack of hearing. In effect they may be aware of these possibilities and check their rearviews more frequently to account for not being able to depend on auditory updates.

If all vehicles were completely silent, it would remove the benefit those of us with hearing gain from the additional input, even though this input isn't strictly speaking necessary. We could and would adapt, sure, but I think that additional factor when cycling does help in some situations. I can see engines making some noise to be advantageous, even if it only makes the difference of one fatality a year, because there is very little drawback.

I believe this is what you mean: https://en.wikipedia.org/wiki/Jack-in-the-box

A minor nitpick, but you can't get more silent than silent since silence is the absence of any noise.

"Silence" doesn't refer to the absence of any noise, it refers to a very low level of noise. The absence of any noise at all is very difficult to achieve (although you can come close: https://www.youtube.com/watch?v=mXVGIb3bzHI). The same goes for other absolutes like "black" (e.g. http://en.wikipedia.org/wiki/Vantablack is arguably "blacker" than other "black" materials).

You're technically correct (the best kind of correct), but your point is moot. Very few words that describe absolutes can be used "correctly" in practice. The logical conclusion is that these words (despite their dictionary definition) don't refer to actual absolutes but rather extremes: silence is not the absence of noise, it's just the presence of a significantly smaller amount of noise.

Heck, even words like "pregnant" aren't absolute in practice. With "pregnant" the implication commonly is "will give birth" (which is why we have euphemisms like "expecting"), so someone who is nearly due can be said to be "more pregnant" simply because they are closer to giving birth (and therefore also have a higher chance of delivering successfully) whereas someone within their first months of pregnancy may often not even want to disclose their state because so many things can still go wrong.

In practice "silent" or "black" is no more absolute than "cold" -- and it would be silly to expect people to refer to zero kelvin when they say "cold", don't you think?

Disclosure: I spent way too much time around linguists as a student.

Thanks for your explanation.

Considering that other animals can produce or hear sounds that humans can't, I guess I shouldn't have used the word 'any'? :)

When I think of silence I tend to think of passively cooled heatsinks or cases for PCs that do not produce any noise that I can hear (even up close). Compare that to a slow-spinning fan that can be effectively silent at a certain distance, but still produces an audible sound if you get really close.

> In practice "silent" or "black" is no more absolute than "cold" -- and it would be silly to expect people to refer to zero kelvin when they say "cold", don't you think?

You're right, although what one person thinks of as cold may not be what another person thinks of as cold. e.g. temperatures in winter in the UK vs Russia or the North Pole. It's all relative.