 The investigation cited as evidence the claim that no blast was audible on recordings of the collapse and that no blast was reported by witnesses, stating that it would have been audible at a level of 130-140 decibels at a distance of half a mile.Demolition proponents say eyewitnesses repeatedly reported explosions happening before the collapse of the towers, and have published videos obtained from NIST, together with indications about when such explosions could be heard in support of the sounds of explosions before collapse.NIST also concluded that it is unlikely that the quantities of thermite needed could have been carried into the building undetected.