The science behind the sound

Weather affects the sounds you hear in the summer from heavy rain and rolling thunder, but it also influences the strength of sounds you hear from Fort Benning.

On a partly sunny day, the blast from a tank will be quieter as opposed to one on a cloudy or stormy afternoon.

This is because low lying clouds cause sound waves to bend or refract back down to the ground – making the noise sound louder.

“We typically see an uptick in public complaints about noise in the summer when we have lots of thunderstorms and low clouds – that’s causing the sound to travel more easily through the atmosphere and seem louder,” says Matt Nichols.

Matt Nichols is an environmental scientist with Fort Benning’s Environmental Management Division. Nichols’ says when it’s a cloudy or stormy day the sound from blasts can reach up to 120 decibels – which is not enough to cause damage to your ears or home, but is noticeably louder than on sunny days.

“So in a best case scenario with ideal atmospheric conditions, hopefully around 90 decibels. On a bad day with low cloud cover, as much as 120 decibels,” says Nichols.

Stronger winds and wind traveling in the same direction as the blast contribute to louder noise as well.

The cooler the temperatures outside, the louder the blasts sound too.

“Sound actually travels better through cold air because it’s a denser medium for the sound waves to propagate through,” adds Nichols.

This helps explain why blasts sound louder at night – especially on clear, cool ones.

Typically, temperature decreases with increasing height. On clear nights – this is the opposite. Once the sun sets, the ground cools quickly and allows the surface to be cooler than the warmer air above. This is called a temperature inversion. That inversion refracts or bends the sound waves downward (just like low clouds) – making tank blasts more noticeable.

David Rogers lives less than a mile from post in Upatoi. His house is near the northeast quadrant of Fort Benning – where some blasts are conducted.

“It varies, but you know it’s mainly during the winter time – some time maybe into March or April – you can hear them. Whenever they shoot, you know it out here cause you can hear it inside the house and all. It doesn’t actually make anything break or fall or anything, but can just feel the shutter of the house,” says Rogers.

After 25 years, David says he and his wife have gotten used to the noise.

“It doesn’t bother me – it does bother my outside cat. I have cat that’ll take off running whenever they start shooting over there at Fort Benning. We also have a neighborhood computer alert system out here that they send out when they’re going to be shooting – normally what size shells they’re going to be shooting – but you definitely know when they’re shooting the tanks and all that out here,” adds Rogers.

Regardless of the noise, Operations Sergeant Major – 129^th Infantry Regiment and Master Gunner Derek Ates says the tank firings are necessary for training.

“The overall good of us training is we’re protecting America’s freedom whenever we deploy to other countries. So in order to do that efficiently, we must conduct this training at live fire caliber – so that is shooting the main gun rounds on the tanks. We have simulators and things that we use, but there’s nothing like firing the real tank so that solider knows how to operate it correctly and how to employ it correctly,” says Ates.

Tank firings are conducted throughout the year, day and night, rain or shine to properly prepare soldiers for war. For more information on when and where tank firings will occur, along with how to sign up for updates from Fort Benning click here.

TIPS ON HOW TO REDUCE OUTSIDE NOISE IN YOUR HOME

Double-pane windows. Most sound enters your home through your windows (the path of least resistance). Double-pane windows will not only reduce outside noise, but provide better insulation – reducing energy costs as well.
Soundproof curtains.
Bookshelves with books.

EFFECTS ON HOMES

A blast would also have to occur within 500 meters of a building or house to cause any damage. Anything farther than that is not at risk to structural damage.

“The army has done a lot of studies on noise – obviously because the army is in the business of blowing things up. Most people in the public tend to have concerns about noise when it reaches around 120 decibels, but we’ve studied this and found any actual physiological damage to your health or damage to a structure won’t occur until 150 decibels – which is much much louder,” says Nichols.

This is good news for realtor John Bunn who sells houses near Fort Benning, around Columbus and Harris County. He says he’s not had anyone ask about tank firings when they’re looking for homes, rather Fort Benning benefits business.

“There are definitely benefits. I think people are really proud to be Americans…are proud to live near the post, and they’re really proud that the army is there. It’s such a great asset to the community, and I can’t imagine this area being here without Fort Benning,” says Bunn.