"Readiness' implies that a military service member can fulfill a mission from all aspects, including having trained properly to master the skills to undertake a given mission, as well as being in the right state of physical, psychological, and overall health.

Our senses have an important function in service members' health and readiness. They are interconnected, meaning they work with each other to allow us to function, move, and communicate.

In the case of hearing and sight, for example, the two dominant senses work together to create the perception of what we experience in the world, according to Dr. Mike Pattison, program manager of readiness and operations optometry at the Defense Department's Vision Center of Excellence (VCE) in Falls Church, Virginia.

"Studies involving sight have found that the visual cortex uses signals received from both the eyes and the ears when viewing the world," he said.

Added Dr. Felix Barker, VCE's director of rehabilitation and reintegration: "Vision and hearing guide nearly all human behavior - as two of our most important senses, they allow us to remotely sense opportunities and threats at great distances compared to other senses such as smell and touch.

"This ability extends to interaction with the environment at a safe distance," he said. "A great example of this is driving, where vision and hearing enable us to safely move through our environment using technological solutions that greatly enhance our access to our world."

Dr. Amy Boudin-George, a clinical audiologist at the DOD's Hearing Center of Excellence, at Lackland Air Force Base, Texas, said "our hearing allows us to listen to others, while our vision allows us to see their mouths, expressions, and gestures to help us confirm what they are saying."

And, said Pattison, "where the visual input is unclear such as at dusk or in a dark building, hearing takes on a more prominent role. Hearing helps us monitor our environment for potential threats or opportunities in directions other than where we are looking, which results in shifts in where we look when necessary."

In fact, he said, "studies have found that the brain has to work harder to hear when we are not looking at what we are listening to."

This is especially true with radio communications, which place all the emphasis on hearing, said Boudin-George.

In the military, this is important because hearing and vision are key to accurate situational awareness and mission success, allowing for coordination within a service member's unit and other units and forces, she said.

"Service members must be able to recognize, identify and locate threats," she said.

"In situational awareness, we rely on our hearing and vision to help us locate the sound source, identify a weapon or vehicle by sight or sound, and understand whether the sound is moving toward us or away from us."

And the more we can use both vision and hearing, the more accurate we can be at those tasks, she said.

Barker calls this combination a "360-degree threat detection system" that can provide service members the "ability to acquire threats detected," as well as "the opportunity to identify, engage and, when necessary, destroy the threats."

Likewise, military operations rely on communication and observation technologies that can enhance service members' sight and hearing, thereby extending their awareness and allowing them to take precautionary measures and enable overall mission success.