Even in loud settings with tons of different noises, we seem to have a knack for focusing in on the most important sounds, particularly sounds of danger. If we're anything like bats, it's because our neurons make those sounds louder.
Our ability to know what sounds to focus in on and which to ignore is still not well understood. That's why Georgetown researcher Bridget Queenan decided to investigate how mustached bats pick out which noises to focus in on. Bats are particularly good subjects because they navigate the world using echolocation, meaning their brains are constantly full of the pulses and feedback of their natural sonar.
In particular, Queenan wanted to understand how bats pick out warning noises from other bats:
"What we are trying to figure out is how a bat can fly around echolocating - screeching and listening to its own individual sounds bouncing back - amidst a whole colony of hundreds of other echolocating bats – and possibly hear another bat saying 'watch out! Bats actually do make these cautious calls quite a bit. In fact, bats have a whole host of communication sounds: angry sounds, warning sounds, and sounds that says 'please don't hurt me."
The answer seems to be in the circuitry of the brain. When the bat's brain registers the presence of known warning sounds, certain neurons dampen the strength of other neurons that are responsible for less important sounds. As far as the bat is concerned, that means the more important noises come in loud and clear, allowing it to avoid trouble. Queenan suspects this same auto-focusing on danger occurs in the human brain as well.
According to Queenan, this process isn't just helpful - it's essential to our survival. Of course, for humans, there might be a curiosity aspect as well:
"All organisms are constantly assaulted by incoming stimuli such as sounds, light, vibrations, and so on, and our sensory systems have to triage the most relevant stimuli to help us survive. As humans we are not only sensitive to a child's cry, but we notice flashing ambulance lights even though we are engrossed in something else. We want to know how that happens."