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MFDR – Four letters that help explain vocal power!


MFDR – What is it and why you should care

I wanted to share with you a concept we’ve been working with a lot recently: Maximum Flow Declination Rate. This one comes from the daunting world of voice science. The concept of MFDR really helps answer a question that many of us struggle with when trying to explain the voice: where does power come from? Ask 10 different voice teachers this question and you may get 10 different answers, and they may all be right! What understanding this concept will do is help you tie everything you’ve been told together.


What is MFDR?

Before I can explain MFDR, let’s back up for a quick second. Your vocal cords (or vocal folds if you want to sound extra smart) open and close generally hundreds of times a second when you make sound. This is also called phonation. It takes air or lung pressure to get your vocal cords to phonate.  Essentially, air is the gas for your engine.

Try this exercise to help you visualise it:
Put your hands together in front of your mouth, like you are praying, and blow air. Now, open and close your hands. When you open your hands, the air flows through them.  When you close your hands, there is no airflow through them.  This is similar to how your vocal cords interrupt airflow from your lungs when you phonate, only much much faster. For women, it can be up to and over a thousand cycles per second!


The Drop!

What Maximum Flow Declination Rate means is the fastest drop of airflow pressure possible in each cycle. In other words, we want to get from lots of flow through the vocal cords to zero as quickly as possible. When we accomplish this, the sound energy that is carried by the airflow gets very excited, and this excitation creates more vocal power! Here’s a video that I like to help this idea:

The faster the people in this ride drop from very high to very low, the more excited they become. So vocal power is not just about creating the sound, but exciting the sound. MFDR is how it’s done.


How do we get MFDR in our singing?

There are 3 ways to get the quickest drop of airflow in your singing.

#1.  Blow more air  

If there is more airflow during each cycle, and it drops in the same amount of time, it will drop faster.  This is good news for those who believe that air “support” is crucial for optimal singing. I think we can all agree that it is. However, we have to be careful not to put all our faith in the breath. It is only one part of the system and can’t fix every problem. We also need to be careful not to overload the vocal cords with air as well. Too much lung pressure and the vocal cords will have a harder time closing. This can lead to excess muscle tension when singing. Lots of air: good. Too much air: bad! 


#2.  More cord closure

If you’re new to this concept, using more cord closure means that every time your vocal cords open and close, or “phonate”, they stay closed a little longer in each cycle. Cord closure is gained by training the intrinsic laryngeal muscles in a careful and specific way.

We give closure a percentage value: sometimes called the “closed quotient” (how long they stay closed in each cycle) or “open quotient” (how long they stay open in each cycle). The closed quotient varies constantly, but advanced singers can maintain a range which, to listeners, will sound constant.  For example: 70-80%.  You need a certain amount of cord closure to create a rich, harmonic sound. If there is very little, your sound will be breathy. How this relates to MFDR is that a high closed quotient will give little time for air to flow through the vocal cords because the open part of each cycle is very short. This small amount of time means the air flow drops very quickly during each cycle, and hence can provide some vocal power.

Although this is one strategy for increasing power, we have to be careful of using too much cord closure. It can very easily lead to excessive muscle tension and vocal fold injury, which then causes the singer to need more lung pressure to sing. A vicious cycle of fatigue!


#3.  Inertance

There’s a little bit of “just go with it” when explaining inertance as it’s a word most singers have never heard before. I’m sure many of you have noticed that some vowels are easier to sing in certain situations than others. It’s a whole other discussion to explain why this is true (look up formants and harmonics at your peril!). BUT, what I can explain quickly is that the way you pronounce vowels can feedback energy to your vocal cords. This energy feedback is one important reason why certain words can feel easier than others. That energy, or inertance, also reduces how much air pressure it takes to get your vocal cords to phonate.  

It will give you a better MFDR too.  The energy feedback will delay how long it takes for the airflow to reach it’s peak in each cycle. Then, when it drops, it drops faster which will give you more power or excitement of sound energy in the air. The concept of inertance can be tricky to wrap your head around. The most important thing to understand is it’s effect. If you pronounce your vowels a certain way, it leads directly to more power with less physical effort from you. This doesn’t mean there’s a right and wrong way to sing, but there is definitely a more efficient or easier way to get power!


What is the best way?

This is where voice teachers will argue all day long. I think we, as an industry, have been guilty of over emphasising one of the 3 way to get MFDR in singing. The answer is that all 3 are important and each singer is different. However, all things being equal, it’s also true to say that the more you can achieve MFDR with your breath and inertance, the less you’ll create wear and tear on the vocal cords. That means delivering your breath and vowels in considered way! Obviously, all three have to work together to create the optimum in your system.



I hope this article gets you closer to understanding where a good deal of the power in your voice comes from. Big thanks to Dr. Ingo Titze for helping us to grasp this one, check out his book Vocology for more information on this and many other important concepts:
Vocology: The Science and Practice of Voice Habilitation – Ingo. R. Titze


Ryan LuchuckThis article was written by Ryan LuchuckRyan is one of Canada’s busiest vocal instructors, balancing a roster of over 200 students. Clients of Ryan Luchuck include Juno, SOCAN and Gemini Award wining artists and professional Musical Theatre stage leads. He is the co-founder of Vocology In Practice (www.vocologyinpractice.com), an organization of high level voice instructors. Through his work with ViP, he has mentored vocal instructors worldwide, including New Zealand, Korea, Switzerland, England and Brazil. Ryan has lectured internationally, including the prestigious Pepperdine University in California. He is endorsed by some of the most respected vocal experts in the world. In addition to his mastery of vocal technique, Ryan continues to perform, still working professionally on piano, guitar, bass and vocals. Visit his website for more information.

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