[dignick]

Unfortunately, this is very wrong! Why does it have to be a sudden sound? The effect the article describes is the same as eg thunder, except an aircraft is continuously moving and emitting sound. The aircraft in the article is not heading directly towards the observer. It simply takes time for the sound produced at a given moment to reach the observer, but the light from the aircraft travels much faster, which is why the lag is observed. It is not ‘sound attenuation’ or ‘hearing threshold’.

[bernulli]

> "Why does it have to be a sudden sound? The effect the article describes is the same as eg thunder"

Well yeah, that's a sudden sound. My point precisely.

So why don't you hear from your observation point the airplane (or all airplanes for that matter) as it takes off, which is when it makes its first noise? And by all means, account for a few ms of light movement if that makes you happy.

[dignick]

> Well yeah, that's a sudden sound. My point precisely.

But you are saying that isn’t like an aircraft - why?

> So why don't you hear from your observation point the airplane (or all airplanes for that matter) as it takes off, which is when it makes its first noise? And by all means, account for a few ms of light movement if that makes you happy.

That is attenuation! The aircraft is far enough away that all the energy from the sound is absorbed by the air and objects between observer and aircraft. Attenuation does not affect the speed the sound travels. But when the aircraft is closer to you, the attenuation is lower so you can hear the sound.

[bernulli]

Because an aircraft does not make a sudden noise? At least where I'm from aircraft don't sound like discrete booms. I'm not sure I understand your question.

> But when the aircraft is closer to you, the attenuation is lower so you can hear the sound.

So we agree after all.

[danachow]

> But you are saying that isn’t like an aircraft - why?

Because last I checked airplanes in cruise flight have a pretty constant engine noise, that’s why.