As 9/11 researcher Jim Hoffman points out at 911research.com, the continuous and rapid explosions of the Twin Towers would make distinct explosions nearly impossible to hear, except perhaps by those who were standing right next to the towers. A news clip from Fox shows witnesses in Midtown commenting that the explosive roar of the two skyscrapers' demise sounded like “another large aircraft flying overhead.” These roaring sound waves were heard miles away.
Furthermore, sounds strongly suggesting explosions can indeed be heard in numerous videos of the towers' destruction, including these videos of WTC 1 and WTC 2, obtained via a Freedom of Information Act lawsuit filed against the National Institute of Standards and Technology by the International Center for 9/11 Studies.
Similar sounds can be heard in videos of the destruction of WTC 7, such as this one, which has been analyzed by physics instructor David Chandler. These new videos corroborate the many eyewitness reports describing loud pops and other explosive noises at the onset of the destruction. These reports were also obtained through an FOIA lawsuit, their release having been denied by the Port Authority of New York and New Jersey when first requested by The New York Times.
Those who would still contend that the sounds heard on 9/11 were not on par with acknowledged controlled demolitions should note a peer-reviewed paper by Danish chemist Niels Harrit, Ph.D., and other scientists, which documented that active thermitic materials were present in the WTC dust. The partially ignited and unignited residue of this energetic material indicates that thermite and nano-thermite played a significant role in the destruction of the WTC skyscrapers.
The literature on these materials states that their shockwave characteristics can be "tuned" for various purposes, which might include reducing the overall volume or sharpness of the blast sounds. Such a capability would make these materials ideal for use in “deceptive” controlled demolitions, in which the muted blast sounds would instinctively be blamed by at least some observers on the toppling buildings' floors hitting each other as part of a "natural" collapse.