As usual in this forum, intentional misunderstanding reigns supreme.
On 9/11, there were no shortage of testimonials from first responders and the public who witnessed the sound of explosions from the
World Trade Center.
Yet members who worship at the alter of denial continue to grasp at any straw that will allow them to continue in their desperate belief that all the perpetrators have been accounted for.
Unquestionably, explosive devices, unless somehow activated in a vacuum, are sound generators.
What I have been trying to point out is that the recording and perception of sound can be strongly influenced by many factors.
Simply put, a typical floor in a building rigged for commercial explosive demolition will have its windows removed as well as its furnishings.
At the time of detonation, the waiting public often hears a countdown followed by the easily heard reports of exploding cutter charges.
A generated sound which is reflected off every hard surface and freely radiated, unresisted by furnishing's absorption and a windowless perimeter.
This situation accounts for why commercial demolitions are clearly heard and why recording devices can more easily pickup the explosion's high frequency sound component.
A typical floor in the World Trade Center on 9/11 was fully furnished and enclosed by sealed windows. From inside, only the loudest sounds generated in the city below would be heard (sirens etc.).
A core detonation would generate sound waves radiating outward, encountering sound absorbing furnishings and finally sound blocking windows.
Of course the windows would yield to the pressure wave but during all this, a good deal of the high frequency sound would have been absorbed and deflected. The sounds escaping the building would be mostly powerful low frequencies (bass which travels well) while its remaining high frequency component (treble which is easily absorbed and/or reflected), would dissipate in the city environment.
For reasons already stated, most usable recordings from 9/11 reveal heavily mixed rumble and boom with little of the telltale high end frequency that makes an explosion discernible from the sounds of structural collapse.
The fact that on-the-scene reporters were obviously using directional microphones further inhibited recording devices from properly 'hearing' background sound.
Unlike microphones, well placed human ears, as revealed by eyewitness testimony, identified the sound of explosions prior to, and during, the rumble of collapse.
http://911review.com/coverup/oralhistories.html
Witnesses to the Towers' Explosions
http://whatreallyhappened.com/WRHARTICLES/911_firefighters.html
9/11 Firefighters: Bombs and Explosions in the WTC
In all instances, and in particular WTC2 and WTC1, once their global collapses were underway any concern about the sound from a massive use of explosives could be ignored and hand waved as only noise from huge collapsing towers.
Case in point, the south tower (WTC2), showed a steady falling stream of what appeared to be molten iron from a corner column area. This activity ceased only moments before that critical corner failed and global collapse ensued. Nano-thermite could quietly initiate this cause of the observed initial topple, and once observed, explosive charges could be triggered according to plan.
