Hydration and the vocal folds

But what if I’m wrong?

[a 10-minute read]

“I learned something new from someone’s course last week and I’m happy with it. Now I’ve come to your course this week and you’ve told me something different. It doesn’t match what I learned last week. Who’s wrong, me, them or you?”

A topic came up on our 2021 “My Singer Has A Voice Problem” Popup Workshop.


We said on the Popup that it takes up to four hours for water to get into the system. We had not one but four people comment with “but I thought it was 2 hours/1 hour/25 minutes/instant?”

Put yourself in this situation. What happens to you if you discover something that you say or think is contradicted? Consternation, fear, disbelief, anger? Take a moment to identify your trigger emotions. You might need to be aware of them before you regain the mindset to examine the different bits of information.

We took some time after the Popup to dig a little deeper into the research. And we ended up with some questions!

In the example of hydration, are we talking systemic or superficial/topical? And how are the biomechanical properties of the vocal folds assessed? Increased or decreased efficiency according to levels of hydration? And whose vocal folds – men, women, children, athletes, professional singers, hobby singers, non-singers?

These questions alone will probably tell you that the “facts” come from different perspectives, different foci, different possibilities. This might explain why you’re getting different answers from different people.

Don’t be upset by this, notice two things. Different people take the same facts and arrive at different conclusions. And different people take different facts and call their conclusion by the same name.

This might need some detective work on your part to sort out. And a knowledge of the difference between facts and experiences.

Some examples

Let’s take facts first. Here’s a Chimeric paper* on hydration published in a peer-reviewed journal. A 20-year-old physically-fit male athlete is dehydrated under laboratory conditions using diuretics and decongestants. The scientist has measured the hydration of his organs (the method of measurement is given in the paper). The subject then drinks plain water to a given level. The same hydration measurements are taken every 15 minutes. The subject’s organs reach an optimal level of hydration after four hours (the description of “optimal level” is referenced in the paper).

From this we can deduce that this 20 year old fit male athlete recovers hydration from an articifially-induced dehydration in four hours on that day in those circumstances, from a given level of dehydration to a given level of hydration.

The scientist would then go on to repeat the experiment and test many other subjects, identified by category in the next paper (age, weight, fitness, possibly original level of hydration) to build up a general picture of, lets say, national-level athletes and hydration.

*Chimeric = mythical or drawn from multiple sources. Essentially I made it up.

Facts rely on other facts. And many of those sponsoring facts come from science papers with remarkably narrow foci. It’s built into the way most research works.

Big Data

So let’s move to Big Data, where the subject list is in the thousands or millions. Certain trends appear. Those trends won’t include everyone, but there will be enough people in the data with similar results that the trends can be identified. That very lack of the personal/individual is Big Data’s greatest strength and also its greatest weakness.


Because it doesn’t always match the individual (you) or your experience. Let’s say you took part in a piece of Big Data research. You’re a forty-something female, relatively fit but perimenopausal. You find you need to drink small amounts regularly. You’re not actually drinking the “8 x 8oz glasses a day” or whatever is recommended, but if you drink the recommended amount you feel bloated. You find if you drink 6 small glasses throughout the day you’re perfectly functional. You can sing, you can teach for hours and you can still exercise and you feel balanced. You don’t fit the outcomes of the big data experiment. But you’ve been told the facts. Should you be following the recommendations and suffering the bloating?


Although we’ve gone slightly off topic, it’s relevant. It’s the difference between facts and experience.

And also the difference between “right” and “wrong”.

Look on facts as being recommendations, trends, possibilities, or if you like, specific generalities. Unless the research has been conducted on you personally and verified by other people getting identical results, facts are a rabbit hole that you can disappear down very easily.

So what’s the best thing to do with facts?

Take the facts as presented to you and “try them on for size”. What’s going to be useful for you as a teacher, as a performer, as a real person in the real world?

Checking the facts on Hydration

Let’s do exactly that, by checking the facts on hydration.

Surprisingly, there are very few concrete facts about hydration per se. Dehydration has been demonstrated to be detrimental to phonation pressure threshold (the minimum subglottal pressure required for the vocal folds to vibrate).

Here’s Sivasankar & Leydon in their excellent 2010 article The role of hydration in vocal fold physiology

“Data from animal and human subject studies have revealed that systemic and superficial dehydration are detrimental to vocal fold physiology. The negative effects of dehydration on voice support a clinical focus on hydration intervention. While there is some evidence for increased systemic and superficial hydration in promoting laryngeal health, further research is needed to validate current clinical recommendations.”

In fact it’s worth reading the whole article to give you a fuller understanding of how different researchers deal with de/hydration. It includes discussions on which papers worked on excised dog larynges, excised human larynges (bench studies), theoretical models, and real live humans. It’s free to read here https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2925668/

Their paper also discusses the methods by various researchers of creating dehydration and hydration (not all use water alone). They comment on hyperhydration, hypohydration, and the concept of euhydration (somewhere in the middle). It’s a long read but fascinating!

Hartley & Thibeault in their 2014 article Systemic hydration: relating science to clinical practice in vocal health state: “Existing voice literature suggests a relationship between hydration and voice production; however, the underlying mechanisms are not yet defined and a treatment effect for systemic hydration remains to be demonstrated. Literature from other disciplines sheds light on methodological shortcomings and, in some cases, offers an alternative explanation for observed phenomena.”

Leydon et al in their 2010 article A meta-analysis of outcomes of hydration intervention on phonation threshold pressure say
“We identified 34 studies that examined the effects of hydration on vocal function. Of these studies, 14 examined the effects of hydration on PTP. Nine of these articles met the criteria for inclusion in this analysis. We observed an average effect size of 0.33, indicating that, overall, hydration treatment demonstrated a tendency to reduce PTP. However, this decrease in phonatory effort did not reach significance at the 95% confidence level. The effects of hydration intervention varied considerably across studies (-0.19 to 3.96). We considered that two factors, pitch level of the task and vocal health of participants, may have contributed to this variability in findings. However, our analysis found that these factors could not account for differences in effect size.”

Quick shoutout to Katherine Verdolini Abbott et al papers from 1992 onwards on hydration and vocal folds, focusing on Phonation Threshold Pressure. And to Jeannie van der Linde et al for their 2019/20 research on hydration and voice quality. Check them out.

Coming up to date, this excellent research article by Marshall et al (March 2021) goes in depth into how Systemic but not local rehydration restores dehydration-induced changes in pulmonary function in healthy adults.
It’s a textbook article on the level of detail in the research process, with many factors accounted for. They’re examining the different effects on hydration levels of drinking (systemic) versus nebulising (topical) and it’s revealing. It’s a dense but enlightening read!



Where do you get your water from?

Even if you put data-driven papers side-by-side, you still need to check the parameters of their data. Is the data just from drinking water, or is it drinking ANY liquid including coffee and alcohol?

More importantly, is it just liquid intake or do you include water derived from your food (from meat to soup makes up to 30% of your full water intake)

Want to know about recommended intakes? There’s REALLY varied advice, which of course depends on food inclusion or exclusion.

Adult males – 3.7litres a day in Canada (Institute of Medicine), 3litres a day in China (Chinese Nutrition Society), 2.5litres a day in Europe (European Food Safety Authority). Exclude water from food and you’re down to 1.5litres a day in Belgium (Vlaams Instituut Gesond Leven). And women are generally advised to drink 0.5-1litre less than men.


2 types of dehydration

So is the definition of dehydration any clearer? As usual, it depends. There are two types of dehydration

water loss (hyperosmolar due to increased sodium or glucose)

salt AND water loss dehydration (hyponatremia) [Thomas DR et al 2008]

The actor Anthony Andrews famously collapsed and was hospitalised during a run of My Fair Lady in the West End due to hyponatremia caused by drinking too much water during performances.

For the purposes of this article we’re going with loss of body water with or without salt at a greater rate than the body can replace it. But even the effects of loss of body water can depend on the task – the US national Athletic Trainers’ Association in their 2017 Position Statement “Fluid Replacement for the Physically Active” differentiate between general athletes and those doing prolonged aerobic activity –
“In athletes, a deficit [of body water] greater than 5% is consistently associate with impaired performance”
“in studies of prolonged aerobic activity, performance was consistently reduced when hypohydration met or exceeded 2% body mass loss.”

Here’s a great 3 minute Hydration tutorial video (2018) from the European Federation of the Association of Dieticians. It’s packed with solid information on hydration and dehydration, and the different advice for men, women and children in different countries. It’s eyeopening!



And I’m going to add one more paper – Shirreffs’ 2003 paper Markers of Hydration Status, in the European Journal of Clinical Nutrition https://www.nature.com/articles/1601895

Shirreffs compares various methods of identifying dehydration with their pros and cons. The easiest (and one of the more accurate ones) is the colour of your urine. If it’s dark, drink more. Although there’s obviously a built-in time delay in the “reading”, it’s why the health workers tell you to “pee pale”.

The author goes on to say “It must also be remembered that classification of the state of hypohydration or hyperhydration depends on the physiological definition of euhydration, which is not as simple as giving the dictionary definition.”



What’s the conclusion?

“Wow, this is detailed, but what does it all mean?”

Let’s go right back to our original questions – What if I’m wrong? What if they’re wrong?

Probably the most important thing for you is not to be right or wrong, but to find out what is most useful to you personally. Which parts of that information are going to be most useful to you in your practice, as a singer in your own voice care, or as a teacher advising your students on voice care. Will the knowledge of saline-soaked dog larynges be useful to that belted F5 or your high C Hojotoho?

The best question to ask is, “how useful is this to me?” Or to put it another way – “Do I need to know this?”


And the answer to the question “how long does it take to hydrate?”

It depends.


Check out our This Is A Voice podcast, season 2 episode 9 where we talk more on hydration, and give our updates on the “thick folds/thin folds” debate.

If you want to confirm what’s useful to your voice use, check out the Learning Lounge, 15 years of practical voice training resources for the singer and singing teacher, for less than the price of one singing lesson. https://bit.ly/VocalProcessLearningLounge