In Reply to: Tracking down a noise posted by Awe-d-o-file on July 24, 2012 at 13:54:45:
Hi
If you live within say 30-40 miles of a large commercial airport, you might be experiencing atmospheric focusing and a jet run up test..
This has happened before because at larger airports, they have an area set aside to test and run up the engines on big jets. These are usually open at the top and the sides are louvered.
Anyway, when there is a warm air layer high above, this can cause sound to be bent back towards the ground forming a sound channel.
When they were developing the Saturn five engine at Marshal Space flight center in Huntsville, occasionally when test firing they would break windows in towns 20 miles away. To check to see if the weather could be causing a sound channel, the used large pneumatic speakers on towers and an array of microphones is the surrounding towns. When the mics were quiet, it was safe to fire the engine.
Anyway, if you sound is only once is in a while the sound could be coming from a fairly distant source.
If the sound is a continuous drone, it might be a pumping station or generating plant somewhere. The wind blowing across the openings in the great pyramid are 'blowing on a pop bottle" except around 3Hz.
Do you have a measurement style microphone?
Best,
Tom Danley
Danley Sound Labs
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Follow Ups
- RE: Tracking down a noise - tomservo 19:08:05 07/24/12 (3)
- RE: Tracking down a noise - pictureguy 00:11:34 07/28/12 (0)
- RE: Tracking down a noise - Awe-d-o-file 16:56:27 07/27/12 (0)
- Great Story on the Pyramids! - Pro Sound Guy 10:17:04 07/25/12 (0)