Why Your Voice Flips—and Why That’s Normal

You don’t have to micromanage your voice to sing well. In fact, the more you interfere, the more you might be getting in your own way. 

Hi, I’m Drew. I’ll be your guide today on The Voice Science Podcast. If you’ve ever wondered why your voice flips, cracks, or shifts gears—this episode is for you. We’re unpacking what’s actually happening and why it’s a normal, even essential, part of how your voice works. This episode was written by Timothy Wilds and edited by Josh Manuel.

Most people take voice lessons for one reason: they want to sing better. That can mean hitting high notes, singing on pitch, or just feeling more confident. Whatever the goal, it usually comes down to replacing worry with the kind of confidence that comes from real understanding and repeatable skills.

Let’s build some confidence by learning about one behavioral habit of the human voice. It’s core to what we explore inside VoSci Academy, launching July 25—a space for singers ready to move from confusion to clarity.

By behavioral habit, I’m referring to how the human voice, based on its anatomical structure and function, is most likely to behave. That idea alone may strike you as odd. I find that many singers assume they tell the voice what to do. To a degree, a singer does have the ability to design the sound elements of their singing. But the best designers start with an understanding of the natural characteristics of what they are working with.

Let’s take a moment for an illustration. As a rule, people like to eat. It is essential for survival, but it can also be pleasurable. The difference between eating to stay alive and having a gastronomic experience depends on more than the eater’s discerning palate. It has very much to do with the person preparing the food. Does the cook have knowledge of the ingredients? What cooking preparations or methods will release the best texture and flavor? Take the incredible, edible egg for example. Overcooked it turns to rubber. It will curdle if added to hot liquids too fast. The key is knowing the ingredient’s nature and characteristics–how is it going to behave.

Let’s apply the same method to singing. Most students are surprised to learn that their voice already has a plan for how to easily sing every pitch in their vocal range. This “factory-installed” instinct is guided by two muscle groups: the thyroarytenoid (TA), which shortens and thickens the vocal folds for lower notes, and the cricothyroid (CT), which lengthens and thins them for higher notes. These shifts aren’t choices—they’re built-in reflexes your voice already knows how to make. In some voice training worlds, this would be described as the difference between thick folds and thin folds.

You may be accustomed to thinking of your low pitches residing in your chest voice (voce di petto) and higher ones in head voice (voce di testa). The two zones, chest and head, are also referred to as vocal registers. The 19th-century vocal pedagogue Manuel Garcia II defined registers as “a series of homogenous sounds produced by one mechanism, differing essentially from another series of equally homogenous sounds produced by another mechanism.” Note the emphasis here on the defining quality of the sound of the voice in the differing registers. Two centuries later, voice science has expanded the meaning of vocal registers. Dr. Minoru Hirano, the 20th-century laryngologist, the originator of the Body-Cover model of the vocal folds, believes they are defined primarily by the specific “vibratory patterns of the vocal folds.” Hirano’s more modern definition, largely the result of scientific advancements unavailable to Garcia, moves beyond a somatosensory and auditory interpretation and draws focus on true vocal fold vibratory patterns to define registers.

This shift in muscular dominance between the TA and CT muscles—what we call the passaggio—is remarkably consistent across singers. For AFAB singers, it usually occurs between C4 and F4; for AMAB singers, slightly lower, between B3 and E4. These transitional zones are easy to discover when sliding from low to high pitch at a moderate dynamic and simply observing how the voice behaves. The singer will experience what feels like a gear change or a flip in the mechanism. This isn’t a mistake—it’s the natural behavior of the human voice. This is why this voice trainer eschews the use of the words crack or break–words that generally cause embarrassment and prompt an apology.

So, what is the benefit of understanding how my voice is likely to behave given where I am in my vocal range? Simply put, it is calming and that is a step towards building confidence. Rest assured that your voice already has a plan for how you will easily phonate every pitch in your vocal range. Your voice is not clueless about how a AFAB sings a C5, or a AMAB a G4. It’s all in the design and you can trust it. Your confidence will grow because you’ll understand how your voice is likely to behave.

This is what we’d call the natural behavior of the voice: it knows what to do, and it does it well—when we let it. But once you understand these habits, you can also shape new ones. But you may be asking: “Am I a slave to the chest vs head, thick vs thin dichotomy?” Are there other choices?” Absolutely! Understanding this fundamental behavioral habit of the voice gives you a foundation to build upon. Remember the earlier reference to the singer as a designer who understands what they have to work with? You are now ready for the next level!

Moving from the foundational level to the next is like shifting from nature to nurture. The behavioral habit of the voice, as defined, is a natural approach to singing. Taking that information and practice, a singer can nurture a variety of different vocal qualities, sounds, and colors. An excellent example of this would be belting, which requires that the singer maintain a level of thickness in the folds into a higher vocal range than normal, meaning, at a pitch level where the voice would have naturally switched to a thinner fold mass. Belting is a nurtured quality and you can learn all about it when you listen to VoSci podcast episode 2.

If recognizing the behavioral habit of the voice switching from thick to thin, chest to head is difficult for you, sing slides from low to high pitch, and vice versa. Observe what the voice is guiding you to do. If switching is difficult, it could be because you are beholden to one register over the other. For example, when sliding from high to low, you don’t flip into thicker folds, in other words, you are cricothyroid dominant. This is a condition I have often seen in singers who complain that they have lost their lower range, with little volume below C4, middle C. I’ve seen this particularly in AFABs with extensive choral experience who have sung under directors who discouraged a chesty sound from either sopranos or altos.

In contrast, singers who are thyroarytenoid dominant, will carry thick folds higher, avoiding the necessary thinning out of the folds to ascend easily to higher pitches. The result is a plateauing of the voice. This is the common complaint from AFABs who swear they have lost their upper range, virtually everything above B4.

If you find yourself in either of these boats, do not worry. Remember: your voice knows exactly what to do. The roadblock at present is nothing more than a phonatory habit you have practiced but it can be retrained.

If today’s episode reminded you that your voice isn’t broken—it’s just following a habit—you’re not alone. Understanding how your voice naturally behaves is the first step toward lasting change.

VoSci Academy opens July 25th. It’s our signature platform for singers who are ready to stop guessing and start growing. Inside, you’ll find structured guidance, practical tools, and science that backs it all up.

Become one of our Founding Members and help shape the future of voice education.

This has been The Voice Science Podcast—where voice science meets the art of singing. We’ll see you next time—and until then, keep singing smart.