SOVTEs have become all the rage in voice studios, and for good reason. There's good science behind them, and singers have found they can be useful in a variety of situations. One reason I love SOVTEs is that they help us to better get to know our voices and how they work. The more I get to know my voice, the more in awe of it I am.
While they all operate with the same general principle at the core, partially closing off the vocal tract in order to increase back pressure, not all SOVTEs are exactly equal in how they work. Choosing the right one can be both a matter of preference and the right fit for the situation at hand. Below are some different types of SOVTEs and when you might choose one over another.
Sustained semi-occlusion
Exercises with a sustain semi-occlusion include:
straws in air
humming
hand over mouth (one of my favs for equipment-less SOVTEs)
The benefit of this type of exercise is that they are easy to do for just about anyone and the pressure can be at least partially adjusted for straws and hands over the mouth. I think these exercises are great as a first step for singers who are getting used to SOVTEs and want to try them out on their own. There's very little risk of them doing it wrong! It's a great way to set students loose to experiment on their own time, if they feel safer doing things on their own before doing it in front of you.
Oscillatory semi-occlusion
These exercises include:
lip trills/buzzes
tongue trills
The main characteristic of these exercises is that they have two sources of vibration, one of which is the vocal folds themselves. The other, in these examples, are the lips or the tongue. What's happening during lip trills, for example, is the lips are rapidly opening and closing, continually creating puffs of air that escape through the opening of the lips, then building up behind the lips when they are closed. It's very similar to how the vocal folds vibrate and rapidly release puffs of air during phonation.
I find these exercises can be difficult for folks that have a lot of jaw, tongue, or facial tension. Those muscles can kind of get locked up, and the laxity that is needed to get the tongue or lips to vibrate is really tough. Conversely, I often find that students that aren't quite getting an adequate air flow can very often get to a better air flow when they try to execute lip trills. Some authors, however, have noted that these types of exercises can help with tension in the extrinsic laryngeal muscles, or those muscles that are around the larynx, like the strap muscles, some neck muscles, and the like. I'd most likely use these together with my client in the studio so we can explore what happens to any tension they may be experiencing. For some, attempting these types of SOVTEs might even help them to feel the tension for the first time! Remember to give the singer a lot of tries and ample time to be able to adequately experience the sensations and changes they may be experiencing. We all need time to feel and analyze before we know what's happening.
Transitory semi-occlusion
These types of SOVTEs are found in some aspects of speech, like plosive consonants and semi-vowels. A plosive consonant, like [b], for example, involves closing the lips completely and then rapidly opening them while the singer phonates. Sounds like this are hard to sustain, of course, but could be helpful in working on onsets.
Similarly, semi-vowels like [w] or [j] (which sounds like a "y" in English) starts with a smaller mouth opening, but doesn't fully close it off, before opening to a taller vowel. [W], for example, starts with an "ooh" and then opens to whatever vowel comes next. I have found the [w] sound very helpful in onset work, especially for clients that have a tendency to spread vowels more than we want.
How do you choose?
Sometimes, honestly, it's a matter of trial and error. But if you know generally what result you are aiming for, perhaps you can look at the above categories of SOVTEs and get an idea of which one might be more likely to work than another.
Because some of these exercises can produce a pretty strong physical feedback for some singers, like buzzing in the face or in the mouth, some singers may not enjoy every exercise. It's important to let every singer have the autonomy to also choose or veto a particular exercise. I think trying new things is great, but every body is different, and there's no right or wrong way to experience these exercises.
What things have you noticed as you use SOVTEs? How do you decide which ones to choose? Let me know anything I've missed! I'd love to learn from you, too.
References:
Nix, J. P., & Simpson, C. B. (2007). Semi‐occluded vocal tract postures and their application in the singing voice studio. The Journal of the Acoustical Society of America, 121(5), 3087-3087.
Hijleh, K. and Pinto, C. (2021). "Realizing the Benefits of SOVTEs: A Reflection on the Research." Journal of Singing, 77(3), 333-344.
Andrade PA, Wood G, Ratcliffe P, Epstein R, Pijper A, Svec JG. Electroglottographic study of seven semi-occluded exercises: LaxVox, straw, lip-trill, tongue-trill, humming, hand-over-mouth, and tongue-trill combined with hand-over-mouth. J Voice. 2014 Sep;28(5):589-95. doi: 10.1016/j.jvoice.2013.11.004. Epub 2014 Feb 20. PMID: 24560003.