Singing High and Low

Lower and upper register vocal fold phonation can be contrasted regarding the:

• Length and thickness of the folds
• Tension of the folds
• Vocal fold mass
• Muscle activity (TA or CT)
• Glottal closure (TA, LCA, IA)

Lower Register

Also known as the modal register, the lower register is characterized by the following:

• Length: The vocal folds are shorter and thicker.
• Tension: There is less tension in the mucosa, which are vibrating more slowly on lower pitches, while the inner body muscles (TA and Vocalis) are more tensed.
• Mass: More of the mass of the fold is active in the vibratory cycle; the process of opening and closing begins lower on the vocal folds (remember they have depth as well as length), thus closed quotient is greater because the process begins at the lowest part of the fold.
• Muscle activity: The lower register is dominated by TA (thyroarytenoid or vocalis) muscle activity; TA activity decreases as pitch ascends in a well-coordinated voice.
• Glottal closure: In a developed lower register, glottal closure is firm.

Phonation in the lower register involves vibration of the entire vocal fold, with the folds first closing then opening beginning at the bottom of the fold and then moving to the top in a wave-like fashion.

In modal or lower register phonation, the vocal folds contact each other completely during each vibration, eliminating the gap between them and obstructing the air. The folds are squared when seen in a cross-cut view. 

This is the divergent vocal fold shape. (Titze 2008).

The body of the folds is thicker, shorter, and stiffer, but the mucosa is more relaxed.  This produces lower pitch. Because the wave action begins lower in the depth of the fold, the singer is using more of the mass of the vocal folds to produce sound.

VOCAL FOLD CONTACT IN THE LOWER REGISTER

*Image by Reinhard (Public Domain) via Wikimedia Commons

This is how the vocal folds work in the lower register. Air coming from the lungs creates a vibrational wave in the folds that begins from the bottom of the fold and travels to the top. The folds open and close rapidly, converting aerodynamic energy to acoustic energy. When you sing a middle C, this happens 256 times per second (Hz).

Upper Register

The upper register is characterized by the following vocal fold characteristics (as compared to the lower register):

• Length: The vocal folds become progressively longer as pitch ascends.
• Tension: There is more tension and stiffening as pitch ascends and the folds vibrate faster for successively higher pitches.
• Mass: Less vocal fold mass is in vibration; there is a gradual elimination of the vibrating element (E Herbert Caesari); vocal fold opening and closing begin higher on the depth of the folds. 

Because of the stretching of the vocal folds and the increasing tension on them as the pitch rises, the edges of the folds become thinner, and the contact surface becomes smaller. 

This is the convergent vocal fold shape. (Titze 2008). 

There is less amplitude of vibration and the pitches produced have fewer high harmonics. Sympathetic vibration is no longer felt in the chest cavity when singing in the upper register.

• Muscle activity: The cricothyroid (CT) muscles become more active. These muscles lengthen and thin the folds by tilting the thyroid cartilage at the front of the larynx. The ligament takes over as the tension-bearing element as pitches ascend.
• Glottal closure: In beginning singers, glottal closure is less firm and the singer’s vocal quality is breathy. Vocal training develops a firmer glottal closure for greater resistance to subglottal air pressure, resulting in stronger and clearer vocal sound.

VOCAL FOLD CONTACT IN THE UPPER REGISTER

*Image by Reinhard (Public Domain) via Wikimedia Commons

When singing higher notes in the upper register, the vibratory pattern begins higher on the vocal fold. The folds are lengthened, thinner, and tauter due to the cricothyroid muscles (CT) tilting the thyroid cartilage forward and down.

Because the folds are attached to the arytenoid cartilages in the back of the larynx, when the thyroid tilts forward and down the folds are lengthened like rubber bands stretching.

When this happens, there is less vocal fold vibrational mass employed in the production of tone and less contact.

If singers attempt to hold on to the TA-dominant thicker and shorter vocal folds of the lower register to sing high notes (in other words, yelling), they will experience strain and ultimately, vocal abuse.

Most untrained singers try to do this in the beginning because the chest voice in singing is similar to the speaking voice and therefore feels familiar. It’s hard to let go of what you know!

But once singers discover the ease and power of the mix, they never go back to pushing the chest voice too high.

Transitioning Between Registers

When singers try to sing high pitches while attempting to hold on to the TA-dominant phonation (heavy mechanism, mode 1), they experience strain. Eventually the voice cracks or breaks.

We call this a flip.

Some pop singers today attempt to compensate for lack of skill in the upper register by yodeling or flipping to falsetto for higher pitches, making an inadequate technique sound like a style choice.

Pushing the lower register too high and flipping into a weak falsetto to sing high notes is technically incorrect and musically unsatisfying.

There is a better way!

This better way is known as mixing.  Mixing is a vocal technique that allows us to maintain the timbre of the lower register throughout the vocal range.

Mix can be compared to shifting gears on a bicycle to go up a steep hill, or shifting gears in a manual transmission automobile. Shifting gears prevents a car engine from burning out. In the same way, singers must avoid burning out their irreplaceable voices by “shifting gears” at exactly the right time.  

When we want to sing ascending pitches from lower to upper register smoothly, there must be a shift from the thyroarytenoid (TA) dominant phonation (shorter, thicker folds) toward a cricothyroid (CT) muscle dominant phonation (longer and thinner vocal folds).

When this is combined with resonance adjustments (F₁ transitioning to F₂), the singer moves imperceptibly through the break.

When we transition through the bridge correctly into a connected upper register mix, it feels like we are doing less rather than more. As we sing higher pitches, the folds lengthen, thin, and begin the vibrational wave process higher up on the folds rather than at the bottom of the folds, so less vocal fold mass is engaged.

The folds are lengthening and thinning, so when we are singing well in the mix it feels like we are doing almost nothing at all! 

It should feel easy to sing in the mix, rather than pushed or strained. So, we are working less hard but far more efficiently when we are mixing correctly.

Mix sounds strong but feels easy!

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