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Stennis Space Center had a giant horn installed in the times when they were testing the Saturn program engines. The purpose was to see what the acoustic conditions were like before testing and thus wait with a test if the sound propagation could cause damage in nearby houses:

Reverberations of the Saturn tests were quickly felt. The acoustical impact was quite evident in the immediate area around the city of Huntsville, and the long-range sound propagation occurred at distances up to 160 kilometers. The result was a rash of accidental damage to windows and wall plaster, followed by a rash of damage claims (sometimes filed by citizens on days when no tests had been conducted). Aware that climatic conditions caused very pronounced differences in noise levels and long-range sound propagation, engineers began taking meteorological soundings and installed a huge acoustical horn atop a tower in the vicinity of the test area. No ordinary tooter, the horn was over 7.6 meters long and had a huge flared aperture over 4.6 meters high. Its sonorous gawps, bounced off a network of sound recorders, gave acoustical engineers a good idea whether it was safe to fire the big rockets on overcast days.

(Stages to Saturn, p80)

Knowing that its testing program depended on public acceptance, NASA continued its acoustic studies, which were initiated in December 1962. The U.S. Weather Bureau and GE personnel operated the MTF Acoustics Laboratory where data were recorded and analyzed for prediction of sound propagation. GE personnel sounded a giant acoustic horn, and the Weather Bureau sent balloons aloft carrying instruments for predicting sound-level propagation to the surrounding communities. The acoustics experts set up measuring devices in the communities surrounding the MTF. The specialists sounded the giant horn several times simulating the test-firing sound levels; recorded the sound levels; and also sent weather balloons aloft to measure atmospheric conditions. The resulting data were fed into computers to determine a sound profile of the area. These tests were done because atmospheric conditions have a direct and major effect on sound travel and intensity. A temperature inversion can cause sound, which normally goes up into the atmosphere, to bounce back to the ground.

(Way station to space, p125/126)

MTF: Mississippi Test Facilities, the name of SSC before it was renamed.

Is this horn still at SSC? Is it used or are more sophisticated methods used nowadays?

Pictures of the horn would be awesome also.

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    $\begingroup$ This mentions Huntsville, which is where Marshal Space Center is, not Stennis. They certainly did do testing of rocket engines at Marshal once upon a time. $\endgroup$ – PearsonArtPhoto Sep 24 '20 at 11:25
  • $\begingroup$ @PearsonArtPhoto that's confusing... The horn is also mentioned in chapter 7 of "Way station to space" (end of p 125 and top of p126), where it is explicitly stated that it is installed at MTF. $\endgroup$ – Ludo Sep 24 '20 at 11:34
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Partial answer -

The confusion arises because the horn started out at Huntsville and was later moved to the Mississippi Test Facility.

enter image description here

I don't know if it's still there and/or still used, though. It also isn't as big as the dimensions given in Stages to Saturn, perhaps they refer to the installation in Huntsville.

Source: Horn Tower (has more pictures)

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