Fletcher-Munson Curves
Fletcher-Munson curves show how human ears hear sounds differently based on their pitch and volume. Two scientists, Harvey Fletcher and Wilden Munson, created these curves in 1933 during their research at Bell Labs.
What the Curves Tell Us
Our ears don’t hear all sounds equally. They pick up some frequencies better than others, even when those sounds have the same actual volume. The Fletcher-Munson curves map out these differences in how we perceive sound.
Middle Frequencies
People hear sounds in the middle range of frequencies (around 1000 to 5000 Hz) most easily. This happens because our ears evolved to be especially good at catching human speech, which falls into this range.
Low and High Frequencies
The curves reveal that we need more volume to hear very low or very high sounds compared to middle-range sounds. A deep bass note must be played louder than a mid-range note for our ears to think they’re equally loud.
Real-World Uses
Audio engineers use these curves when they design sound systems and mix music. They help create better-sounding recordings by adjusting different frequencies to match how people actually hear them. Radio stations also use this knowledge to make their broadcasts sound clear to listeners.
