Sound Localization: Judging Sound Direction (page 2)
Surprisingly, you and your friends probably will have had a harder time determining the precise direction of sounds that happened in front of them!
How do people tell where a sound is coming from? Different animals have heads and ears that are capable of capturing sound in different ways. Owls have flat facial disks that act like satellite dishes, capturing sound. Many bats have large pinnae (“ears”) that collect sounds.
People have pinnae too—but we call them ears. The part of the ear that processes sound is actually on the inside of your skull, and the things we call ears are our sound-collectors, or pinnae.
Our pinnae sit on the sides of the head. This means that it’s easy to hear sounds that are coming directly from the left or the right. When a sound is above us, below us, or behind us, it can be harder to pinpoint exactly where the sound is coming from. However, we make up for this weakness with our eyes! Humans usually use our eyes to detect things that are right in front of us, because our eyes point forward.
We can still accomplish sound localization and determine where a sound is coming from even when that sound isn’t directly to the left or the right of us. A sound that comes from behind us and to the right moves into our ear pinnae and gets amplified in a certain way—meaning the sound is louder in one of our ears than it is in the other. Then, the brain takes that information and decodes it. Over time, we will have heard many sounds from this direction, and we get trained to realize that the particular amplification pattern this direction produces means that this sound comes from behind us and to the right.
A sound that comes directly from the back of your head is hard to figure out because it doesn’t move as easily into your ear pinnae. It might echo off something in front of you, and that could help. Usually people turn their head slightly when they hear a sound behind them, and this helps their ears capture the sound and helps their brain decode it.
Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state’s handbook of Science Safety.