"Scott M. Kozel"
comcast.net> wrote:>>
>> The sound of air rushing is something that is quite easily swallowed
>> over long distances.
>>
>> The very low frequency component of jet engine noise travels
>> extremely far distances, because that is what low frequency sound
>> does. The low frequncy rumble of aircraft taking off at the Portland
>> airport used to rattle my windows, when I lived some 8 miles from the
>> takeoff path of the runway. The high frequency component was lost
>> completely, but that low frequency stuff was terrible.
>
> You made that up out of whole cloth.
I'm not quite sure what part you think he made up. If it's the
suggestions that low frequency sound propagates farther than higher
frequencies, then he didn't make that up.
http://web.mit.edu/aeroastro/partner/projects/project1-qanda.html
It's also true that sounds that are generated close to the earth's
surface attenuate faster than sounds that are generated above the earth,
which is also a difference between the sounds generated by rail and those
generated by aircraft.
> When we lived in Florida, we
> were in a quiet neighborhood 5 miles from the regional airport, and
> in-line with the main jet runway, and we never noticed that phenomena,
> and that was at a time when airliner jet engines were much noisier
> (first generation turbojet engines, on B-707, B-727 and DC-8), than
> later engines.
I lived within a mile of a major airport, with a heavily-used rail line
running along the airport boundary between us. Only occasionally could I
hear the rail traffic, mostly when the wind was blowing in the right
direction. On the other hand, the aircraft maintenance base would often
run up engines for testing, which could be clearly heard. It was the low
frequency sound of the engines that could be clearly heard.
> Besides, it would take sound 40 seconds to travel 8 miles, making it
> rather difficult to correlate it to the airport in any case.
Aircraft sounds are distinctive enough that you can tell where they came
from.
