The Fletcher Munson Curve Explained

Confused by the Fletcher Munson Curve? We break it down into an easily understood explanation. 

fletcher munson curve

Many people may go about their day to day lives thinking that mixing music is a relatively straightforward task. After all, you just listen to the music and either boost or tone down certain parts as needed until it sounds good, right? There’s actually a lot more to music recording and mixing than what meets the eye. Our ears are incredibly complicated, and when mixing music their complexity needs to be accounted for.

The Fletcher Munson phenomenon is a major part of music recording and mixing. It can play a huge role in whether the song you’re listening to sounds great or gives you a headache. This phenomenon is portrayed visually by a graph known as the Fletcher Munson Curve. Through this curve, people are able to see exactly how the phenomenon affects people listening to music in their day to day lives. It’s the scientific level beneath the songs we love to sing that helps to explain just what makes them sound so interesting to the human ear.

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What is it?

The Fletcher Munson phenomenon describes an issue in which the human brain perceives the various sounds (frequencies) in a song differently depending on the volume the frequencies are set at.

Our ears are sensitive to loudness and frequencies. The Fletcher Munson Curve shows how our ears are sensitive to equal loudness throughout the frequency range.

For example, while listening to a song at a low volume, the person will perceive that the higher and lower frequencies will be less pronounced, whereas the mid-frequencies will seem louder. Meanwhile, listening to the same song at a high volume will cause the high and low frequencies to sound louder, and the moderate tones to drop in volume.

In reality, the notes of the song didn’t change at all. It’s the same song regardless of the overall volume, the human brain simply perceives it differently. The Fletcher Munson Curve is a graph that displays this phenomenon as it occurs, and assists those who create and record music in finding the right strategy for creating a great sounding song. It also causes music producers to consider how they want to attract people to their music, and keep them interested in it. 

Why is it Significant?

The main idea is to create music that people want to listen to. If the music is somehow jarring or annoying, people aren’t going to purchase the songs and albums that are created. Generally speaking, it’s better for the music to sound better as the volume increases. For this reason, when many people who record and edit music work, they make sure to listen to the songs at a high enough volume that they will be able to recreate what happens when a potential customer might hear the song and decide to turn it up.

mixing desk

If the music sounds worse as it’s turned up, it’s going to become a problem. Most of us like to turn up the music we like to sing and dance to from time to time, so it’s important that music be enjoyable while at a higher volume. Music that people want to turn up is music they will also want to purchase because it sounds good, which is hugely important for those who are recording the music. If you decide you want to record your own music, it’s a good idea to keep in mind that the volume can affect a person’s perception of sound.


The Fletcher Munson phenomenon can cause a problem when those who are recording or editing music aren’t aware of it and listen to the music at a low volume during the process. The low volume may cause the high and low notes to sound ineffective, and the person may choose to boost them. However, once someone listens to that edited song at a higher volume, the high and low notes will sound loud and potentially even jarring. This leads to songs having a low quality sound that potential customers won’t enjoy.


Naturally, those who sell music want to keep sales going. They want to music to sound good so that it sells well, so it’s important to keep in mind issues like the Fletcher Munson phenomenon and have answers ready to address it and keep the music sounding wonderful. The main idea is to keep a good balance of frequencies so that the listener finds the overall sound pleasing. Luckily, there is a relatively easy fix to make sure the phenomenon doesn’t damage the listening effect. Simply listen to the song at a higher volume while editing in order to match what potential customers will experience.

Relation to Headphones and Speakers

Variations of these equal-loudness contour graphs are used to represent the frequency response of headphones and speakers.

When purchasing a new set of headphones you should always check out the frequency response to see how the headphones react throughout the frequency range. Studio type headphones have a flat frequency response that faithfully reproduces sound. There will be no big dips or peaks in the graph. These represent drops or boosts in loudness. If you seek something a bit livelier, then day to day headphones like those you get with an iPhone will have peaks in the low end to give you that bass boost.


Overall, the Fletcher Munson Effect plays a large role when it comes to what music sounds good and what music makes you want to cover your ears. If ignored, it can result in music that sounds terrible when it’s listened to at a higher level. 

That would be the exact opposite of what most music recorders are going for. Seeing as how most creators want to share the music and have people enjoy it, keeping Fletcher Munson in mind is going to be a great way to help make sure the songs sound great and people want to purchase and share the music they create or edit. The Fletcher Munson Effect can be a useful tool in the success of musicians and producers everywhere.

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Image Credit: By Lindosland at en.wikipedia [Public domain], via Wikimedia Commons

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