Vocal Folds and Hydration

Gillyanne & Jeremy tackle two controversial AMAs in this episode:
What they REALLY think about "thick and thin folds", and why the topic of vocal fold hydration is so confusing.

Gillyanne and Jeremy go in depth into vocal fold behaviour, why the terms thick and thin are misleading, how we can change pitch and volume while singing, and which words they now use in their teaching.
And in answer to four people's questions on hydration, Jeremy shares some of the research findings on hydration (systemic and topical), why the answer to "how long does it take to hydrate" isn't as straightforward as it sounds, the different types of dehydration, and why you can drink too much water.

Mentioned in the show:

My supporting article on hydration and the vocal folds is here:
https://vocalprocess.co.uk/hydration-vocal-folds/

The Voice Clinic Handbook (2nd edition, Harris et al) https://amzn.to/3ch17HN

Verdolini-Abbott et al papers
https://pubmed.ncbi.nlm.nih.gov/7823546/ Dependence of phonatory effort on hydration level
https://pubmed.ncbi.nlm.nih.gov/12003510/ Biological mechanisms underlying voice changes due to dehydration

Sivasankar & Leydon The Role of Hydration in vocal fold physiology 2010 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2925668/ 
 

Hartley & Thibeault Systemic hydration: relating science to clinical practice in vocal health 2014 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4157110/

Leydon, Wroblewski, Eichorn & Sivasankar A meta-analysis of outcomes of hydration intervention on phonation threshold pressure 2010 https://www.jvoice.org/article/S0892-1997(09)00074-5/fulltext

Marshall et al Systemic but not local rehydration restores dehydration-induced changes in pulmonary function in healthy adults https://journals.physiology.org/doi/full/10.1152/japplphysiol.00311.2020

Hydration video tutorial from the European Federation of the Association of Dieticians http://www.efad.org/en-us/euhhac-hydration-resource-center/tutorial-on-hydration/

US National Athletic Trainers’ Association Position Statement “Fluid Replacement for the Physically Active” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5634236/ 

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Transcript

Jeremy   0:00  
So the first thing you've got is the surface area of the vocal folds. The second thing you've got is the speed of movement of the vocal folds together. Now this is actually how fast together they clap. This is not about how many times per second they clap, which would be pitch. This is about how fast they move together and move apart. And,

Gillyanne Kayes  0:20  
yes, what I want to say because I'm guessing where you're going is to talk about volume. Yeah. I think as singing teachers, we can fall into the trap of to access that volume, we must make our vocal folds thicker. Yeah. And that's not what you were talking about. You were talking about speed of closure. So that can contribute perceptually to what some people might think of as a thick fold. Totally. Are you happy with that?

Jeremy   0:49  
Absolutely.

Gillyanne Kayes  0:50  
We didn't even discuss this one.

Jeremy   0:51  
That's really good.

Announcer  1:04  
This is a voice, a podcast with Dr. Gillyanne Kayes and Jeremy Fisher. 

Jeremy   1:14  
Hello, and welcome to series two, episode nine. I just had to go back and count them. Welcome to this is a voice. I'm Jeremy Fisher.

Gillyanne Kayes  1:22  
And I'm Dr. Gillyanne. Kayes

Jeremy   1:24  
and welcome back. Well, thank you for that. How are you feeling?

Gillyanne Kayes  1:28  
Well, it's nice to be in the salad

Jeremy   1:30  
in the salad again. I don't I don't particularly like being in the salad. It's all that greasy dressing.

Gillyanne Kayes  1:38  
It's nice to be back in the saddle again, even if only partially so that was a great start wasn't it?

Jeremy   1:46  
even if we can't quite get the English right. But that's fine. So what are we doing today?

Gillyanne Kayes  1:50  
Well, we well, you actually and our trainer Anne Leatherland have been doing Popups while I've been busy recuperating. 

Jeremy   2:00  
Yes. 

Gillyanne Kayes  2:01  
And we've had some interesting questions come up. And we thought that we would start our series two nine by talking about some of these questions and riff around them.

Jeremy   2:10  
Well, the two Popups in question were the Belting & Power Sounds Popup and the My Singer Has A Voice Problem Popup. And a question came from each of them, which is really interesting. So we got to AMAs today, and we have a recording of the first one. So do you want to go straight in with that? 

Gillyanne Kayes  2:25  
Yes. 

Jeremy   2:26  
Okay.  This is Ashley.

Ashley  2:26  
Hello Gillyanne and Jeremy. Firstly, thank you for the brilliant Belting & Power Sounds Popup workshop a couple of weeks ago. My question has come out of this workshop, and is regarding terminology. So my question is, what does thick and thin fold mean to you? And how helpful or unhelpful is this term when we're talking about belt and power sounds on various pitches? Thank you both very much. And I look forward to hearing the podcast.

Gillyanne Kayes  2:50  
It's a corker of a question isn't it?

Jeremy   3:05  
It is a great question

Gillyanne Kayes  3:06  
It is a brilliant question. Actually, I really appreciate, Ashley, that you sent us that question. Okay, 

okay, strap in! 

Yes. Can I start? I've had plenty of time to think about this. I think what we should say first and foremost is that these terms thick and thin fold, they're descriptors, and they're not actions. And I think that's really important as teachers and singers that we understand it, it's not an action that we can do. I'm going to make my folds thick. I'm going to make my folds thin. And I would also say that they're not definitive sounds either. No, I think they're probably a range of different timbres, if you like. So, actually, I've got a story for you. When we started talking about this, for those of you who are listening, we were very much kind of of the mind that these are terms that we don't use very much nowadays. And then guess what happened? Yesterday, I was giving a session to a client. And it was a term that she came up with herself. When we were working on a kind of mechanism 1, a chest mechanism sound in a popular music song. And I said, Well, that was great. How does it feel? Oh, it feels thick and dense. And I've got to tell you, Jeremy, that I found myself saying, well, that's why we sometimes use the term thick folds. And what what that taught me is that there is a value in these terms, if you're building proprioception with your students, so this client had some proprioceptive feedback from using her voice in a different way. And the word thick was the word that she used. I didn't feed it to her. So I think it's important that we have that awareness, from a pedagogical point of view.

Jeremy   5:13  
Okay, but erm 

Are you going to argue with me now? 

I'm not... But I am, which sort of sums my life up really. Okay, the reason I'm going to argue, that I'm not going to argue is because you know that you and I like to come to a person that we're working with, and use the language that they're using as far as we can. And this is also really interesting, because when, when somebody in front of you says that's thick, in a way, you can't know what it is that they mean, because they're feeling it, they're translating it, they're, they're putting a word on it. And the word that they use might be different to the word that you use. So even if somebody does use that word, I will go, I will want more information. It's like, Can you describe it a bit better? Thick, as opposed to what? Can you demonstrate something that is not thick, so I can hear where you're coming from?

Gillyanne Kayes  6:04  
And this was a very different internal sensation for her than singing in her classical voice. Okay. And one of the things that we talked about later in the lesson, when we were exploring how to match that sound, further up in her vocal range, was the idea that the thickness that she felt lower down would not feel as thick as she went higher up. And I think that's also a really important point, because what often happens with the use of these terms is they become polar opposites. 

Jeremy   6:39  
Oh, it's not a binary system

Gillyanne Kayes  6:41  
They're not opposite states. It's not a binary system, as you've just said very elegantly, absolutely not. I've got another story. This is a few years ago, Jeremy and I were invited to do a masterclass in workshop at a college up in the north of England. And we were invited by someone we trained, who had inherited students from another teacher. And those of you who are teachers, you always know how difficult this is, they come with somebody else's language, somebody else's exercises, somebody else's concept. And you have to find a way to navigate that in a comfortable way with them, to move them forward. Rather than saying, Oh, well, this is all wrong, your teachers trained you incorrectly, that's actually not a positive way to work with a student, even if it's privately what you think. Which wasn't the case. And there was a young woman singing, I would say she was 17-18, singing, you know, really working very hard in a piece of contemporary musical theatre. And she was trying really hard. And it was solid, and it was loud. And I broke a bit of a rule because we got to the end, and I made a joke of it. And I said, Well, thank you very much for working so hard. But do you really need to sing the shit out of your thick folds? And we all had a bit of a laugh about it. And what we did then was we adjusted that the heaviness, the sub glottal pressure, the amount of effort that she was using, and you know what's so interesting, then, apart from the fact that was a better performance, and she had more ease. We heard more of her.

Jeremy   8:32  
Oh, that's really interesting. Yeah. And I come across this a lot. The whole binary thing, which is it's either thick, or it's thin, and it's got to stay thick and thick is thick, and you know, you're you're thick all the way up and all of that about the whole thick, thin thing, which is it's immovable.

Gillyanne Kayes  8:53  
Yeah, and I think it's something that singing teachers have grabbed, and they have grabbed it from clinicians. So as part of preparation for this, one of the things I did was I referred to our Bible, which is the Voice Clinic Handbook. Yeah. And I had a look at some of the way that Mr. Tom Harris talks about the thickness and consistency of the vibrating mass of the vocal fold. And he likens it to the idea that you have different thicknesses of string. So if you're thinking about a stringed instrument, the pitch and the tonal quality of that vibrating string, depend not just on the tensioning of it, which is largely what's responsible for the pitch, but also the thickness or vibrating mass of that string. So if you have a string that's overwound, or if you have, you know, a single sort of string of metal, if you like, or if you have gut strings, so steel strings, gut strings, overwhelmed strings, they all sound different. So when we're talking about the thickness and thinness of the vocal folds, that's actually probably the most significant thing that we're talking about. And should you head to the Voice Clinic Handbook and read this particular chapter, which is laryngopharyngeal mechanisms in normal function and dysfunction, I recommend that you read the next few pages, and you will discover that there is more than one way to skin a cat, which is actually one of the subheadings, which I rather like.

Jeremy   10:39  
There's something I want to to unpick having made a fairly dramatic statement. The difficulty for me is that this is not about the words themselves, but the way that they're applied to singing and singing teaching, and students and teachers, which it seems to be that if the sound is loud, it's thick folds. And if the sound is soft, it's thin folds. And first of all, that's so binary. And secondly, it's so inaccurate. And I want to say why it's inaccurate. Because let's talk about volume. And the relationship about with volume and how you can make your output loud. And there are several things that you can do. So we're talking about the surface area of the vocal folds that come into contact, essentially, the bigger the surface area that comes into contact, then the more air that's displaced, and the louder the sound. So if you just get your hands and clap them together, and you clap with your whole palm and all four fingers, then actually what's happening is that as your hands come together, they are displacing an amount of air. And because that surface area of your hand is quite big, it's displacing quite a lot of air quite fast. And therefore that's making the air around it disturbed in quite a big way. If you do the same thing, but instead of all four fingers, you just clap with two fingers, then you still getting a clap, but because that surface area is not moving as much air it's not as loud. So the first thing is, how much surface area are you using?

Gillyanne Kayes  12:15  
I think that's very sensible. And part of that surface area. equation, if you like, needs to take into account what's happening at the deeper layers. Because we have a layered system. 

Jeremy   12:25  
Haven't got there yet!

Gillyanne Kayes  12:26  
No, but I think it needs to be mentioned. And also, you know, I think we should be forgiven for being simplistic because we are not clinicians. But there's a considerable interplay going on between the intrinsic muscles of the larynx as well, in order to facilitate all of this. So it's really not a one stop or two stop shop.

Jeremy   12:48  
Okay, I have six or seven of these. So you sort of shortcut a bit, but I want to go back, okay, back. So the first thing you've got is the surface area of the vocal folds. The second thing you've got is the speed of movement of the vocal folds together. Now this is actually how fast together they clap. This is not about how many times per second they clap, which would be pitch. This is about how fast they move together and move apart.

Gillyanne Kayes  13:14  
And, yes, what I want to say, because I'm guessing where you're going is to talk about volume. 

Jeremy   13:21  
Yeah. 

Gillyanne Kayes  13:23  
I think as singing teachers, we can fall into the trap of to access that volume, we must make our vocal folds thicker. 

Jeremy   13:32  
Yeah. 

Gillyanne Kayes  13:33  
And that's not what you were talking about. 

Jeremy   13:34  
Nope

Gillyanne Kayes  13:35  
You were talking about speed of closure. 

Jeremy   13:37  
Is correct

Gillyanne Kayes  13:37  
So that can contribute perceptually to what some people might think of as a thick fold. 

Jeremy   13:42  
Totally. 

Gillyanne Kayes  13:43  
Are you happy with that? 

Jeremy   13:44  
Absolutely. 

Gillyanne Kayes  13:44  
We didn't even discuss this one.

Jeremy   13:46  
Nope. That's really good. Okay. So the next thing and this is a really interesting one, because this is also about output is how much downward pressure is there above the vocal folds 

Gillyanne Kayes  13:58  
Ah, you're talking about the supraglottic forces 

Jeremy   14:01  
Supra glottic forces, which is basically as the the the sound has been made at the vocal folds and the vibrations are travelling up through your throat, and is the throat completely open with no obstructions whatsoever, or are there things going on. And this is of course where SOVT comes in a semi occluded vocal tract. So for instance, you could back the tongue slightly which would interfere with the airflow up and out and that might make it stronger because you have more back pressure down onto the vocal folds.

Gillyanne Kayes  14:34  
Can I can I interject? This is the second edition of The Voice Clinic Handbook. 

Jeremy   14:39  
Alright

Gillyanne Kayes  14:39  
Can I come out with another factoid>

Jeremy   14:41  
You can. 

Gillyanne Kayes  14:42  
So, Harris et al. quote Titze 2011. And Titze says, it's a highly tempting generalisation that large vocal folds especially thick vocal folds, produce a lower frequency simply because they have more mass needs to be abolished /

Jeremy   15:00  
Hurray, 

Gillyanne Kayes  15:01  
Vocal fold vibration is a wave phenomenon. That's what Jeremy's just been talking about standing and travelling waves, in which the tissue does not move uniformly, and therefore no centre of mass, or the mass itself can be defined easily.

Jeremy   15:19  
Ooh I like that. 

Gillyanne Kayes  15:20  
Isn't it gorgeous? vocal folds dimensions do affect frequency, but differently for length, thickness and depth.

Jeremy   15:28  
Good. I'm liking that.

Gillyanne Kayes  15:30  
Yeah, so it's a real kind of interplay of ideas. And do you want to say a bit more?

Jeremy   15:36  
I want to go just right back to basics, which is, let's assume let's go with the thick fold title for the moment. And you go, Okay, I am singing C4, middle C, whether I'm a man or a woman, I am singing C4, and C4 in a woman is going to be middle low, and C4 in a man who's going to be middle high in their range. So my vocal folds are thick to a given amount of thickness.

Gillyanne Kayes  16:01  
You've set a vibrating mass, yes. Before doing anything to adjust

Jeremy   16:11  
Yes I am singing C4, to a given thickness to a given volume. I want to keep the same type of sound. And I want to keep the same type of volume. But I want to jump up an octave.

Gillyanne Kayes  16:27  
Oh, good luck with that.

Jeremy   16:29  
So now I'm on C5. 

He's a bass.

Yeah, well, I don't do C5. But but some guys do. C5 has never passed my lips. But some some guys do. And a lot of women do. So let's say I achieved that. And if you want to say I'm in belt, if you want to say that's fine. If you want to say I'm in a chest voice, or I'm in a power sound, whatever, that doesn't actually matter for the moment what title you give it, the point is that you are now vibrating at approximately the same volume, an octave higher. So your, your vocal folds are vibrating twice as fast. Are they still thick. Because if they are the same thickness, how did you make them vibrate twice as fast, something has to change. And if something has to change, I don't believe that you can take the same level of depth or thickness or mass or anything up an octave and it still be the same mass. So the whole business of my vocal folds are thick, and my vocal folds are thick all the time simply doesn't make sense the moment you bring pitch into it, because somehow the vocal folds have either got to tense or lengthen or do something to make them vibrate faster. And the moment they do that you have lost your quotes thickness level.

Gillyanne Kayes  17:48  
Or you may need to lose the lose some of the mass by not working so hard at the level of the vocalis, at the level of Thyroarytenoid.

Jeremy   18:00  
So we've done surface area, we've done what happens when you raise pitch we've done how much downward pressure there is, there's something else as well, which is how many muscle fibres in the vocalis are involved in phonation.

Gillyanne Kayes  18:15  
That's just where I'd got to.

Jeremy   18:17  
Yep. So it's also this idea that if your vocal folds are thick, then the muscle is on. And all the fibres are on and they're all tensed and everything is. And first of all,

Gillyanne Kayes  18:31  
Are we sensing a theme here, dear listeners?

Jeremy   18:34  
I'm not completely convinced that that's the case anyway.

Gillyanne Kayes  18:36  
I think that's important. Can I I'm going to interrupt because they are. The origin of the question was in relation to belting and power sounds. 

Jeremy   18:44  
Yes. 

Gillyanne Kayes  18:45  
And what I think you've nicely described is that even if you are in a power sound, whether you want to call it belting or not, as you go up a fifth, there will be an adjustment of the vibrating mass. And this seems to me to be the key thing. Because there is this idea of there's going to be for each individual. And maybe for each timbre that we're looking for, there's going to be a point of critical vibrating mass where you cannot vibrate any faster at that mass and therefore there has to be an adjustment. And there are a variety of adjustments. 

Jeremy   19:24  
There are a variety, that's the thing. Okay, the first thing that you might be able to do is to actually stretch the vocal fold from outside, which will tense it and a tensed vocal folds will vibrate faster. But there's another thing that you can do, which is to release some of the muscles inside the vocalis, which will actually have the same effect without stretching the vocal folds. Because the tensile strength inside the muscle goes down and therefore that can vibrate faster. There's a third thing that you can do, which is to release the muscle completely, which in our book is M2. Some people call it falsetto, some don't. But if you think about going up to that C5, you might go into M1, but you can use super glottal forces in order to make the sound stronger. And therefore, your your vocalis is not particularly active in the sound. But it's still another way of getting up to that C5, and you can make it extremely powerful with acoustic forces.

Gillyanne Kayes  20:26  
So just just because it's loud, doesn't mean it's necessarily thick. 

Well, yes.

Is that 

Jeremy   20:32  
Yeah, absolutely is. Yeah. I know. And by the way, some people don't even acknowledge the fact that there is what was it adducted falsetto, which is in the science literature, but they go oh, falsetto is always breathy. No, it absolutely isn't. There is a thing called adducted falsetto, and that's partly due to the super glottal forces. So you can have an extremely powerful adducted falsetto.

Gillyanne Kayes  20:58  
So where does that leave us? I think for us, the way that we work with our singers and with our teachers, is that if these terms are discussed, and I mean, let's face it, they were in my first edition of Singing and the Actor, you know, they've been out there for a while, that we will talk about it as being a continuum. And we prefer to say thinner, thicker, and that there's more than one way to thin the vocal folds. And there's more than one way to get a heavy perceptually thicker sound. 

Jeremy   21:30  
Yeah. 

Gillyanne Kayes  21:32  
And I think that's really important. I also think, you know, we've been talking about the vibrating mass of the vocal folds. And we've already said that, if you're an octave higher, you're never going to be as thick as you were an octave lower. And I think it's highly unlikely. Let's put it that way. And because from a mechanical point of view, that's not going to be very functional. So back referring to the question, we think you could be making a power sound on a thicker or thinner vocal fold on an M1 or an M2. And we're not saying that M1 and M2 necessarily equate with thick and thin. 

Jeremy   22:13  
They don't

Gillyanne Kayes  22:14  
We're not going to go there. I think the terms are they useful? My advice is use with caution.

Jeremy   22:24  
Okay, I'm gonna throw some questions to people. Let's assume that we are talking thicker and thinner. So my first question you've already heard, which is how do you raise pitch? And just asking that question alone will make you think, how do you raise pitch and keep the vocal folds thickness exactly the same? That's a curious question. My second question is volume. How do you sing the same note at different volumes?

Gillyanne Kayes  22:57  
Yeah, what are you doing? 

Jeremy   22:59  
What do you do? And the moment you start asking yourself those questions, you might go, Well, I don't know. It's like join the club. There are certain things that we do know. And there are certain things that we don't if you think for instance, about the one thing that we haven't mentioned, which is breath pressure

You're talking about sub glottal pressure

Subglottal pressure, which is,

Gillyanne Kayes  23:19  
We have, we mentioned it in passing, it whizzed by

Jeremy   23:22  
we did we did, we waved at it as it went by, it's a combination of the amount and speed of air that's coming up from the lungs and the amount of the vocal folds resist it. So subglottal pressure, as far as I'm concerned, is directly underneath the vocal folds. And is caused by both amount and air speed from underneath, and the resistance of the vocal folds from above. And I mean, in its simplest terms, you can have you can hold your air back, or you can feed it upwards. You can make your air go very fast through vocal folds. Or you can make it go slowly, you can trickle it through. So

Gillyanne Kayes  23:59  
the airspeed is only happening in the open phase.

Jeremy   24:02  
Yes, yes. Yes. 

Gillyanne Kayes  24:05  
Just to be clear, 

Jeremy   24:06  
Isn't that exciting? So I mean, if you like this instantly, three questions that you ask yourself, which are all completely useful questions, and they all part of singing, they're all part of performing. They're all part of artistry, that you go well, the moment I put those questions in, how can you have thick and thin 

Gillyanne Kayes  24:26  
as opposites 

Jeremy   24:27  
well, even just the words thick and thin, do not include any variations on the same note or on different notes

Gillyanne Kayes  24:35  
and the other factors such as the subglottal pressure, etc, etc, and supraglottal

Jeremy   24:39  
And in a way, that's why I don't use them at all anymore, because in a way, they're so vague. And also in a way, they're so easily applicable to 55 million different things. And one person can say that's thick folds and the next person listening can go No, that's not

Gillyanne Kayes  24:56  
and you know what I mean? kind of thinking back You know, because obviously, it was in my book. And you know, that's what was out there in terms of some of the pedagogical knowledge that was being put out at that time that I wrote the book. I think it felt like, 25 years ago, 30 years ago, it felt more concrete than what, you know what my lovely singing teacher when I was training as a classical singer, you know, the most physiology I got from her was breathe out to sing,

Jeremy   25:29  
which is very sensible

Gillyanne Kayes  25:30  
Kind of bit of a no brainer, but you know, Yes, okay. But it wasn't terribly helpful. She taught me to sing a phrase wonderfully. But it just seemed more concrete at the time. And the thing is, it's just not as simple as that. I think that's what we'd like to say,

Jeremy   25:47  
Yeah, I'd go with that. So in a way, I don't use thick and thin at all anymore, I'm much more interested in using M1, M2 and all the variations that each one of those can have. Because in M1 - and M1 and M2 refers to the vibrational mode of the vocal folds and what the vocal folds themselves are doing, how they're working, and what's on and what's off. And I think what's interesting about M1 and M2 is that within those, you either of them, you can change the surface area of the vocal folds, you can change the speed of the movement, you can even change how close together or far apart the vocal processes is are, you can change how much downward pressure there is, the only thing you can't do in M1 that you can do an M1 is to change the number of muscle fibres involved in phonation. It's pretty much the only thing you can't do. And because you can do that now we're on M1 and M2, a whole world of colour and variety, and descriptors open up.

Gillyanne Kayes  26:48  
Yeah, I mean, we've both found that enormously helpful. And I will say, I cannot imagine myself now ever saying to a student, can you thicken your folds? Can you thin your folds? 

Jeremy   27:01  
And the question would then be how? It's really interesting because these essentially, these words, although they're very strict, simple and straightforward, are conceptual. And they cover a multitude of sins. And I think that's why I don't use them anymore. Is because they're so vague. 

Gillyanne Kayes  27:17  
Cool. Are we done with that Ashley?

Jeremy   27:20  
have we answered your question? 

Gillyanne Kayes  27:22  
Are you any clearer? 

Jeremy   27:26  
So we use them, essentially...

Gillyanne Kayes  27:28  
Use with caution. 

Jeremy   27:29  
We use them when somebody else uses them. But even then, we don't decide what that person means we actually find out what they mean themselves. Yeah.

Gillyanne Kayes  27:38  
And then feed it back to them. Yeah. And reframe if necessary,

Jeremy   27:42  
and reframe if necessary. Yeah.

Gillyanne Kayes  27:44  
Okay. All right. Well, that was rip roaring.

Jeremy   27:49  
We had the next Popup that we did was the, my singer has a voice problem with Carrie Garrett. And it was such a great Popup course, it was such a great workshop. And we had some very interesting things happen afterwards.

Gillyanne Kayes  28:04  
So Carrie Garrett, highly specialist...

Jeremy   28:07  
Highly Specialist Speech & Language therapist voice, and also a singing teacher and also a singer. Yes. So she actually comes from all angles. And that was really great on that course, because we had somebody who was not just experienced in the voice clinic, but also experienced as a performer and experienced as a performer in contemporary commercial music, not just classical.

Gillyanne Kayes  28:27  
And I wasn't there for that at all. In fact, I haven't seen it. Carrie did an in-person day for us back in 2020. 

she did

In February 2020, I think, and because obviously, we're not doing in -erson courses in that in that way anymore. At the moment, we asked her if she would do us a two hour Popup.

 it was very interesting, because we made a statement

about hydration.

Jeremy   28:58  
And the whole thing about hydration. And it was interesting because four different people came up afterwards and said, but I thought it was... and the statement that we made was it takes about four hours for water to get into your system and as far as the vocal folds, and basically to hydrate you. And people came up and they said well, I thought it was two hours. And somebody else said Well, I thought it was a one hour. Well, I thought it was 25 minutes. Well, I thought it was instant

Gillyanne Kayes  29:24  
Eight was another one we heard. And I think the last one was about 25 minutes. Yeah. So we were not daunted.

Jeremy   29:32  
No, I mean, we

Gillyanne Kayes  29:34  
We both headed off down rabbit hole.

Jeremy   29:36  
We did. We did and boy are there some rabbit holes. So the first thing that we did was we went to the literature to find out who has the definitive answer. How long does it take to hydrate? And I've actually written an article about it, which I'm going to publish with this this podcast.

Gillyanne Kayes  29:54  
Do you want to say a little bit first of all about systemic versus topical?

Jeremy   29:59  
Yes. So the first thing is, what type of hydration are we talking about? There's two types. Basically, one is systemic, which is your entire body. And the other is topical, which is basically spraying on to the surface. Bear in mind that if you drink something, it can't be topical, because when you drink, your vocal folds close completely, and the water goes, nowhere near your vocal folds, if it did, you'd cough. So the only way that you can get topical water onto your vocal folds is by steam or nebulizer.

Gillyanne Kayes  30:33  
So we don't hydrate the vocal folds directly, we hydrate the body, 

Jeremy   30:39  
we hydrate the body. 

Gillyanne Kayes  30:40  
And the idea of the systemic is that therefore, that water has gone into the body. And it assists with efficiency of vocal folds vibration, and I'm going to let you talk a bit more about this, I might ask you questions as we go along. Okay,

Jeremy   30:55  
so the first thing I went to is what is hydration? And the moment you go into the question, what is hydration? You go into the question, what is dehydration? And there was an even one that I've not heard of which is euhydration, eu hydration, which is a balanced hydration. So hydration, dehydration, and there's another there's that there's a further one isn't there?

Gillyanne Kayes  31:19  
You've just said it, eu

Jeremy   31:21  
know, there's there's like super hydration where you have too much. Okay, but I'll come to that in a moment. So the question first is, what's dehydration? What are the effects of dehydration. And to that you go to various papers, and a lot of people have done studies on dehydration and their effects. And I'd want to shout out to Katherine Verdolini-Abbott, because she has done some great papers with Titze, on the effects on the vocal folds of hydration, they're very good. So and we will put links to them. Certainly, you can read the abstract, you might not be able to read the whole thing. And she chose particularly as her feature phonation threshold pressure. Phonation threshold pressure is what is the least amount of energy force that you can use to get your vocal folds vibrating, what is the gentlest sound that you can make and the least effort that you can do essentially. And what she discovered really, and I am paraphrasing here, so Katherine, if you are listening, then I do apologise if I get it wrong. What they discovered is that dehydration affects the phonation pressure threshold pressure, I was a problem with that phrase PTP

Gillyanne Kayes  32:33  
Just say PTP,

Jeremy   32:34  
PTP. It affects the PTP, to make that threshold go up, so you have to work slightly hard. So

Gillyanne Kayes  32:40  
the effect for the singer therefore is it's going to feel more effortful to make a sound,

Jeremy   32:45  
we are talking tiny, we are talking fractional, but they have to work slightly harder. It's almost like the vocal folds are slightly sticky,

Gillyanne Kayes  32:53  
and they might need a higher breath pressure. So they're having to take a bigger breath to get the vocal folds vibrating. Yeah.

Jeremy   32:59  
And again, I don't think the effect is enormous, but it's there. And if you're a highly experiencing, you're going to notice it

Gillyanne Kayes  33:06  
well. And I think you might also notice something like that over time. You know, if you're talking all day on zoom, yeah. Assuming that, you know, perhaps your hydration levels aren't what they need to be your systemic hydration levels. Then as you go through the day, you might find that you're having to push harder, take more breaths, in order to continue speaking, I would say those are the sorts of things that might be a sign that your phonation threshold pressure is increasing.

Jeremy   33:37  
Yep. So and Verdolini's... I think the first paper came out in 1990. It was certainly 1992. And I came right up to date with 2020.

Gillyanne Kayes  33:50  
He's done a survey of the literature,

Jeremy   33:52  
we are Jeannie van der Linde and et al because she works with a lot of different people really interesting what she's doing. She is doing research on hydration and voice quality, mostly on female voices. That's quite interesting. Look up those, again, I'll put links in I want to go the place to go when you're looking on it sort of generalised topic like this is somebody else doing the literature review for you. And there are three, I think, really good papers to to have a read of. And the first one I want to start with is Sivasankar, and Leydon 2010. At the role of hydration in vocal fold physiology, they have some cracking stuff in this. It's quite a tough read because there's this graphs and charts and things. But it's absolutely worth working your way through because they looked at a whole load of other people's research and analysed what they'd done. And what they said and I'm quoting "Data from animal and human subjects studies have revealed that systemic and superficial dehydration are detrimental to vocal folds physiology". Yeah, okay. dehydration. dehydration, systemic and superficial dehydration - keep up! - are detrimental to vocal folds physiology, the negative effects of dehydration on voice support a clinical focus on hydration intervention. So they, you know, this is what they they 

Gillyanne Kayes  35:16  
they recommend

Jeremy   35:17  
no if you like this is what people were recommending. "While there is some evidence for increased systemic and superficial hydration in promoting laryngeal health, further research is needed to validate current clinical recommendations". Now, this was really fascinating, what they were saying in 2010. And interestingly, we were asking Carrie about this, and she was asking around, and it's been really fascinating hearing what other people have said, which is we all have recommendations, and there isn't that much research to back the recommendations up, which is really fascinating. 

Gillyanne Kayes  35:55  
Or it could be more from what you've told me from the reading that you did, is that there's no firm concurrence of opinions on timing. And that's the key thing, isn't it?

Jeremy   36:09  
Because, or even amount,

Gillyanne Kayes  36:11  
and amount. Yeah, because I can remember being told two litres of water a day, and then taking on board the four hours in advance of whatever you needed to do. And I know that singers in drama schools and actors in drama schools, they're always walking around clutching their bottles of water, their litres of water, and voice clinicians, speech and language therapists very typically are advising more water and more hydration for their clients. And there are good reasons for this. But it's interesting about these kind of rules that people come out with. So what did you find out Jeremy, in terms of amounts?

Jeremy   36:54  
Ooh Yeah. 

Gillyanne Kayes  36:55  
Are you ready for that?

Jeremy   36:56  
That was really fascinating.

Gillyanne Kayes  36:57  
I was really surprised when he told me

Jeremy   37:00  
the first place I think you should go. If you're interested in this. There's a brilliant three minute video on hydration. It's a tutorial video by the European Federation of the Association of Dieticians. And I'll give you the link in the show notes. It's absolutely packed with information in three minutes. And it's really fascinating, because the first thing I didn't realise was that the recommendations are for different amounts of water for men and women. Obviously, different amounts of water for children. But even within the women, you've got different amount of water for women, a different amount for pregnant women and a different amount for lactating women. And actually, it's the lactating women that need the most water. But even within that this is where the fun starts is the recommendations. And there are two different bodies that they refer to. It boils down to approximately two litres a day for men, and one and a half litres a day for women. But

Gillyanne Kayes  37:59  
I'm so glad because I find it really hard to drink two litres of water.

Jeremy   38:03  
Yeah, but it depends where you live. Because in Europe, the recommendation is two litres a day for men and one and a half litres a day for women. But if you're in Poland, it's half a litre more for each one. And I have no idea why Poland is different. Because Mexico is two and one and a half and China is two and one and a half. So in general around the world, it's two litres a day and one and a half litres a day. So that was really fascinating. So

Gillyanne Kayes  38:34  
it doesn't actually depend on where you live. It's just the finding

Jeremy   38:36  
it's different. It's the findings. But now let's go to where your water comes from. Which is is it liquid? Or is it from food? Because 

And what kind of liquid?

What kind of liquid, Absolutely. So if you just go with liquid and food 70 to 80% of your liquid intake comes out your water intake comes from liquids, so it can be water, but it can also be tea, coffee, alcohol, beer, soft drinks, it can be anything that's all counted as liquid intake 70 to 80%. 20 to 30% comes from food which you really wouldn't necessarily notice

Gillyanne Kayes  39:13  
soup is an obvious one 

Jeremy   39:14  
Well, meat. Yes. I mean, literally anything you eat has water content into some kind

Gillyanne Kayes  39:20  
and didn't you look at a study where they had to stop their subjects eating lettuce? Yes, because that's the high water content. Lettuce, cucumber tomatoes.

Jeremy   39:29  
Yep, there was a Oh, I gotta mention that study because it is amazing. This is Marshall et al March 2021. It's absolutely up to date. They go in depth into hydration on pulmonary function. Now they're dealing with with breathing in particular. But the way that they've written up their paper is amazing. They are so detailed. They've got every they list every piece of equipment, but not just that. They actually have catered for excuse the pun, almost every variable that might happen. And one of the things that they did was they took a food diary before the people did their experiment. And they had to do the experiment over two sessions, because one session was on systemic hydration, which was drinking, and the other was on topical hydration, which was inhaling, and they had to do the two on separate occasions. And so what they insisted that the subjects did was that they ate exactly the same thing. Each time.

Gillyanne Kayes  39:30  
They're really controlling variables

Jeremy   40:32  
Really controlling variables. 

Gillyanne Kayes  40:34  
mm, nifty

Jeremy   40:36  
And they checked the quality, they check the water content in the atmosphere, they did all sorts of things in that paper,

Gillyanne Kayes  40:42  
did they find any difference? in things like body mass index? How did they How did they control for that? and gender?

Jeremy   40:51  
Well, I want to go to.. Erm gender they did, they did spot a difference, too. But I want to go to a different paper, because this is where I thought let's go to the sports people. Because I'm really interested that the sports people might have something to do with this. And I've got to find the reference for it. Because

Gillyanne Kayes  41:11  
obviously, if you go to the gym, there's always water on hand, isn't it? And you're told to stay hydrated?

Jeremy   41:18  
Yep. Can't find it. Nope, lost it, okay, can't find the reference at the moment, but I will put it in the show notes. It was something like the American Association of Athletics Trainers put out a statement in 2017. And they were talking about systemic hydration. And one of the indicators of a lack of systemic hydration is body mass index. So if your body mass changes more than 2%, over a very short period of time, it indicates that you're dehydrated. And it also, of course, is not across the board. Because it depends, it depended for them what type of athletic activity that people were doing. So you had your standard athlete if there is such a thing, and they could go anything up to 5% body mass loss, and they were still okay, past 5%. And they were starting to get performance drop off. And also brain fog. So they weren't able to concentrate as well. But if you are a long distance aerobic athlete, so I'm assuming marathon runner, you only had to drop 2% and and your performance nosedived. And it's really interesting, because I'm thinking of singers, and particularly opera singers, as being more of your athletic, long term aerobic. Yeah,

Gillyanne Kayes  42:45  
yeah. Like the long distance runners. Yeah.

Jeremy   42:47  
But then interestingly, you can't really separate musical theatre from opera because in musical in opera, there's not that much athletic dancing, and musical theatre. There is.

Gillyanne Kayes  42:59  
And also, I mean, you know, when performances are the norm, you would probably perform two or three times a week, maybe four at the most, whereas as a musical theatre singer, it would be six to eight shows. So your vocal load is potentially higher than the operatic voice.

Jeremy   43:21  
I'm going to I'm going to pick that up. Because actually, I was corrected on that years ago, when somebody said, I think it was in Australia. And somebody said, I am a member of the Australian National chorus. We sing six days a week

Gillyanne Kayes  43:33  
now, right? Yes, well, that's

Jeremy   43:34  
correct. And that's a fair comment.

Gillyanne Kayes  43:37  
I'm glad you did pick up on that. Actually,

Jeremy   43:38  
I want to go one more place, which is what type of dehydration are we talking. And actually, this is, in a way, this is really important, because we're talking about hydration, but hydration is the opposite of something. And, you know, you must drink water, you must drink water, because you need to keep hydrated, but from what? So I want to talk about dehydration. And there are two types. And they are really interesting to know about. The first one is hyperosmolar, which is water loss and an increase in sodium. So your water drains away, but your salt is left there. And that's hyperosmolar. 

Gillyanne Kayes  44:16  
So you've got an intensification of some of the electrolyte 

Jeremy   44:20  
You do. and the second one is hyponatremia, which is both water and salt loss. 

Gillyanne Kayes  44:27  
And there's a famous actor

Jeremy   44:31  
Anthony Andrews was doing the role of Professor Higgins in My Fair Lady in the West End and collapsed. Fortunately not on stage. He was he just finished the show and gone home I think. But he collapsed and he ended up on a drip in hospital for three days. And he in fact, he was unconscious. Not for the three days but he was unconscious, and that was hyponatremia because he'd been drinking too much water and he estimated that he'd been drinking between five and seven litres a day. Just any time he went off stage, he was swigging the water before, during and after 

Gillyanne Kayes  45:04  
And probably visiting the loo.

Jeremy   45:05  
 And because of that extreme use of water, he'd actually diluted his tissue salts so far that he lost consciousness.

Gillyanne Kayes  45:13  
So it is possible to drink more water than is good for your body. It is and I just want to say about this, you know, thinking about the the litres of water, you know, the two litres or the one and a half litres. I would expect Jeremy to need to drink more water than I need

Jeremy   45:34  
I can I just say I'm rather larger than Gillyanne is

Gillyanne Kayes  45:36  
And my BMI is 19.3 or something. 

Jeremy   45:40  
And mine... isn't

Gillyanne Kayes  45:42  
Yeah, no, indeed. Yes, it is. Yeah. So where can we leave them? I

Jeremy   45:52  
I want to go back to the original question, which is the original question was how long does it take? And the answer is, I couldn't find out. 

No. We did try. We really tried. 

I mean basically, if anybody out there has the answer to this, which is how long does it take, and they can give me paper references. Fantastic. Please. Email in or speakpipe in speakpipe.com/Vocalprocess and actually, you know, put, because I actually really am interested to know and I know that in some papers, the only way to 25 minutes, and in some papers, they waited an hour or two hours. So which is where I think this confusion comes from. It sort of depends which paper you read, who says what, but in a way, it's it's a bit the same really as the thick and thin folds because you have to ask the right questions.

Gillyanne Kayes  46:45  
It also depends where you start. I mean quite a lot of these studies, because they had to have their had to start people off on the same baseline. They had to start them off in a state of dehydration, otherwise there's nothing to measure. Yeah, hopefully most of us aren't in that state. So when we get to... Jeremy's grinning at me

Jeremy   47:06  
well now because I want to talk about dehydration, because in a lot of the papers, they didn't de hydrate them naturally. They gave them decongestants. diuretics. So you are unnaturally dehydrated before you start. And then the question becomes, when you ingest the water and you wait an hour, is the body reacting as it would normally do each day? I mean, there's just so many questions.

Gillyanne Kayes  47:28  
So let's see if we can find a place to leave the listeners. So again, we're going to say things to think about. Is there an impact on your voice? Have you noticed an impact on your voice dependent on how much or how little water you drink? Yes, just maybe keep a diary for a week. And notice it if you're using your voice. There is an impact on the body generally and on your homeostatic balance that that is unquestionable. Yeah. Well, Jeremy's quoted a very nice study on impact on voice from Kitty Verdolini-Abbott and colleagues, your body mass index might make a difference. The environment that you're working in, might make a difference. I can remember doing presentations, where I was having hot air blown at me from a rather old fashioned overhead projector, and finding that I was losing my voice at the end of the day, because I was hot, and it was very drying. Be aware of things like that. Also, what activity are you doing? Are you a dancer? Are you dancing and singing at the same time either as a, you know, a pop backing vocalist, or as a musical theatre singer, it's highly likely that you're going to need more water than you would if you were standing still and singing. Yes. And think about your vocal load. How many hours a day are you working? How long are you speaking for at a time and find out what works for you. And when you're advising your students, bear in mind that they may be a different size from you. And they may be working in a different environment and give them advice that allows them to be flexible.

Jeremy   49:23  
There's one more thing I would say which is we're talking we talked earlier about people swigging water during lessons, and I'm going to say too late. Because what we're really talking about when we're talking about hydration is body water balance. And that's input/output. It's like what level of hydration is your body in general. And if you just drink those two glasses a day or two, I'm sorry, to one and a half or two litres a day in general, then your body water index should be enough to keep you hydrated. And then all you're doing really is replacing stuff that You then use in a performance situation, you're not trying to swig all your water intake down in one go. So

Gillyanne Kayes  50:07  
we're keeping our levels up generally. I'm glad you've said that, because it just occurred to me that this whole sort of story, this whole narrative has come about maybe for two reasons. One, which is anecdotally, many of us do not drink enough water. And the second is, there's a tendency for people to drink the water when their throat feels sore when their throat feels dry. And what we're saying is, it's likely that that's too late, hence the advice from singing teachers and coaches and clinicians to hydrate earlier.

Jeremy   50:46  
So in answer to the question that came up, is it four hours? Is it two hours? Is it one hour? Is it 25 minutes? The answer is yes. 

Find out what works best for you 

Find out what works best for you. Okay, I think we're probably done.

Gillyanne Kayes  51:04  
I think the overall title of this podcast should be "it depends".

Jeremy   51:10  
So if you have any questions that you want to ask us for the next podcast, then please go on to speakpipe.com/Vocalprocess, ask the question, we will play it

Gillyanne Kayes  51:21  
and we'll put some references to articles and to the Voice Clinic Handbook, and so forth and to that little video

Jeremy   51:29  
Oh, the video, which is lovely

Gillyanne Kayes  51:31  
In the show notes, yes. And we look forward to hearing from you. Bye,

Jeremy   51:36  
bye bye. 

Announcer  51:49  
This is a voice, a podcast with Dr. Gillyanne Kayes and Jeremy Fisher.