Equal-loudness contour

Imagine listening to music. Some sounds might seem louder than others, even if the music player says they are the same. That's because our ears are super picky!

They hear some sounds, like a squeaky toy, much better than others, like a deep rumble. An equal-loudness contour is like a special map that shows how loud sounds seem to us at different pitches, or how high or low they are. It helps us understand why our ears play favorites!

Long ago, smart scientists named Harvey Fletcher and Wilden Munson wanted to figure out this ear trick. They did experiments with lots of people to see which sounds they heard as equally loud. They drew lines on a chart, and these lines are called equal-loudness contours.

Think of it like drawing a treasure map for sound! Newer maps have been made since then, using even more information, to make sure they are super accurate for everyone.

Our ears are like super-sensitive microphones, but they are best at hearing sounds in the middle, like voices. They aren't as good at hearing very high-pitched sounds, like a tiny whistle, or very low-pitched sounds, like a big drum. So, even if a very low sound and a voice sound are at the same strength, the voice will seem much louder to you!

Equal-loudness contours show this difference, helping us understand how we hear.

Have you ever seen a 'Loudness' button on a stereo or TV? That button uses the idea of equal-loudness contours! When you turn the volume down low, that button makes the very high and very low sounds a little bit louder. This is so you can still hear them clearly, just like you would if the volume was turned up high. It makes music sound balanced and awesome, no matter how loud or quiet it is!