Semi-Occluded Vocal Tract

What is an SOVT?

Semi-occluded vocal tract exercises are frequently used in the voice studio and clinic as one of the most effective ways to increase efficiency and ease of singing. SOVT exercises involve a build-up of resistance in the vocal tract that creates back pressure. Pressure coming from below the glottis from the lungs meets back pressure caused by the resistance in the tract changing the way the vocal folds vibrate. Creating a “squared-up” position with greater contact area and less contact time increases the sustainability of the sound. There are three different categories of SOVTs:

  1. Steady-state semi-occluded vocal tract postures remain in a semi-occluded state during the duration of the exercise.

  2. Transitory semi-occluded vocal tract postures begin in a semi-occluded posture and then transition away from this state.

  3. Oscillatory semi-occluded vocal tract postures transition back and forth between semi-occluded and non-semi-occluded.

SOVT Exercises

    • Straw phonation

    • Nose pinch

    • Bilabial fricative

    • Humming and other nasal consonants

    • Closed [u]

    • [v] buzz

    • [j] and [w] glides

    • French glides (puis, oui)

    • Bubble phonation

    • Lip trill

    • Tongue trill

    • Raspberry

Incorporating SOVTs

SOVTs are a great way to begin your vocal warm-ups, soothe the voice after prolonged or high-impact voice use, and are a tool to create more efficiency in your repertoire!

  1. Lip trills: ensure a consistent vibration and focus the energy of the trill at the center of the lips. This requires high airflow and will get the most out of the exercise.

  2. Bubble phonation: place a straw into approximately 5cm of water. Use your lips to create a tight seal around the straw so there is no air leak at the mouth. Sing a vocalise or a section of your repertoire keeping the straw around 2cm deep in the middle voice and about 4cm deep in your higher range (above the passaggio for men, and the 2nd passaggio for women).

  3. Straw phonation: begin with a plastic straw and experiment with its diameter by pinching to create more resistance. Note the differences you perceive in the ease of singing with the straw and immediately after. Sing vocalises or passages from your repertoire through the straw.

Additional tips!

Some may experience discomfort with SOVTs that are particularly restrictive, like singing through a cocktail straw, for example. While these tools can produce strong effects, you will still see positive benefits from a larger-diameter straw. Find what works best for you!

Few singers may also experience negative voice effects through certain SOVTs. If it becomes harder to sing or the voice sounds more unstable, it is likely caused by a complete closure of the velopharyngeal opening. This is the soft palate sealing off airflow to the nasal cavity. A small leak in the nasal cavity has been proven to positively affect the aerodynamics of the voice by allowing the propagation of both high and low frequencies. Perform any SOVT with a nose pinch and ensure the sound has an element of nasality. It may help to feel the vibration in the nostrils as you pinch.

SOurces

Acoustic, Aerodynamic, Morphometric, and Perceptual Changes During and After Semi-Occluded Vocal Tract Exercise: An Integrative Review. Apfelbach CS, Guzmán M. Journal of Voice. (2024)

Major Benefits of Semi-Occluded Vocal Tract Exercises. Ingo Titze. Voice Science and Technology. (2018)

Spectrum Effects of a Velopharyngeal Opening in Singing. Gill BP, Lee J, Lã FMB, Sundberg J. Journal of Voice. (2020)

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