Changing the Bullet’s Sound Signature

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The US Pentagon wants to develop a quieter rifle bullet that will prevent the enemy from determining the location of the U.S. soldier who fired it. The defense administration seeks a technology that would reduce or change the sound signature, in terms of magnitude, frequency and/or duration, of a small caliber projectile through the use of active noise reduction methods, according to sbir.defensebusiness.org.

The Department of Defense research project, titled “Active Noise Control for Small Caliber Ammunition,” aims to apply advances in noise cancellation to the battlefield.

The Pentagon notes the possibility of dual-use applications for noise-canceling bullets, “including state/local governments, and commercial.” In addition, “Potential opportunities may exist to produce technologies which will reduce hearing loss in high-intensity sound environments.”

While noise suppressors fitted to a rifle can dampen the bang of a weapon being fired, “bullets traveling near or greater than the speed of sound generate a ballistic crack or sonic boom. This is the sound which is generated outside of the weapon and cannot be addressed by a simple weapon suppressor.”

A round from a 5.56- or 7.62-millimeter rifle generates about 164 decibels for someone standing three feet away from the weapon, according to nationalinterest.org. For now, the Pentagon isn’t interested in quieter pistol bullets, but it is interested in whether noise-canceling technology can be applied to larger crew-served weapons such as machine guns.

The Pentagon admits there are several technical challenges. It wants a meaningful reduction in both the sound of the bullet being fired and the sound as it flies through the air. Yet the solution should not affect the ability of the projectile to accept electronics now being fitted to smart bullets. Perhaps most important, a quieter bullet shouldn’t result in a less lethal weapon.

At the same time, a new American technology now lets soldiers detect the direction of gunshots. The Boomerang Warrior-X developed by Raytheon BBN Technologies provides immediate hostile fire location awareness to individual soldiers and gives unit leaders shooter grid coordinates, according to the company. These situational awareness enhancements improve coordinated team responses to hostile fire.

According to gpsworld.com, incoming shot announcements are transmitted to a built-in speaker or an earpiece while a lightweight display provides range and azimuth of the shooter position. The system compensates for the soldier’s motion and continually updates the threat’s location on a wrist display.

This summer, an undisclosed Gulf nation has awarded a direct commercial sales contract to Raytheon BBN Technologies valued at more than $10 million for the delivery of 2,000 Boomerang Warrior-X systems during the next 12 months.