Teaching The Brain To Understand The Location Of Sound
The world is full of strange and indistinguishable sounds coming at us from all directions. But being able to tell where a noise is coming from, can mean the difference between life and death in dangerous situations.
Now, an evolving new field of study shows promise for better hearing in very noisy environments and avoiding danger among the din.
For soldiers in the field, it’s important to be able to pinpoint where the sound of gunfire is coming from. Same goes for people working in potentially dangerous hard hat areas and people wearing earbuds, that block the sounds around them without realizing the potential danger.
“Hearing is sometimes called the forgotten sense,” says John Casali, professor of industrial systems engineering at Virginia Tech and founder of the Auditory Systems Lab.
Casali points out that the ear is extremely sensitive to sound, because it’s pretty much always on. “Our hearing is even on when we're asleep, albeit, at a lesser sensitivity level. And it is a sense that's always available, present, and ready to deal with acoustic stimulation in our vicinity. That's why it's so important."
And using ear protection in a noisy environment actually makes things worse for the wearer.
“So, there's a tendency when that occurs to take the hearing protector off or, you know, loosen it. And this is one of the reasons that we think that hearing loss and tinnitus, or ringing or whistling in the ears, is the most prevalent injury among veterans today.
That dilemma is something Colonel Brandon Thompson experienced himself.
"There's a trade off between trying to function and complete the mission but maintain a level of protection for hearing," Thompson says." And oftentimes, soldiers will err on the side of getting the mission done, as opposed to protecting their hearing.”
That’s what led Thompson and his colleagues to come up with a way to teach people how to hear better in noisy places. Thompson is a former graduate student at Virginia Tech, now an assistant professor of systems engineering at the U.S. Military Academy at West Point.
Thompson explains, “Anything that you put over the ear or inside the ear is going to train how you locate sounds. And our study shows that we can retrain that ability to locate the sound in a fairly short period of time and in a setting that everyone would have available” such as an office, or any small room.
But it's important to note, PALAT is not a device that enhances hearing. It’s actually the training on the device, that teaches a person to better isolate and pick out certain sounds amid a steady background noise. It’s a sound they invented for testing purposes and even gave it a name.
They call this 'Dissonance.'
(Monotonal droning sound playing)
And once you learn to tune it out, to sort of hear around it, you’ve got it and, you can take it with you anywhere, because there’s nothing to carry but the memory of certain sounds that are important.
To test the system, instructors played sounds people could easily recognize, who were then asked to determine which direction it was coming from.
“We played the sound so that they can recognize it and then they have to respond," Thompson explains.
"You’re trying to train the brain what is sounds like when the noise is coming from behind you. It may sound like it's coming from in front, but it is coming from behind. And so that repetition of knowing where it's coming from and listening, is what causes the brain begin to map or learn it.”
Thompson won the prestigious Briggs Award from the American Psychological Association for his dissertation, for developing a device they call PALAT, which stands for Portable Auditory Localization Acclimation Training.
Soon they’ll test PALAT in different locations: The U.S. Military Academy, the Office of Naval Research, the State Department, among others.
The long term goal is to increase something they call Auditory Situation Awareness, a new field in the study of sound, not only to aid the military, but also, for our increasingly noisy world.
***Editor's Note: Radio IQ is a service of Virginia Tech.