Navigating The Passaggio

The passaggio! Well, what can we agree on about the passaggio? How many are there? Which ones are we talking about?

Let’s talk about ‘the’ passaggio. The dreaded one, the one that feels like a brick wall to some.

What can we say and agree about it? Well, it’s where things get tricky, I think there’s consensus about that.

So why does it get tricky there?

Partly and possibly understandably because the muscles in the larynx are required to pull more, stretch more, create more stiffness etc. which all require more effort.

Partly because the resonator itself provides resistance (or more general a term: impedance), which is frequency dependent and also dependent on the shape of the resonator.

Partly because the resonator dimensions affect the vocal fold vibrations. We know this instinctively from the days when we used to make tones with a grass straw. You remember, you put a nice piece of grass between your thumbs, and then the magic happened when you cup the hands just the right way so that you can get a nice vibration from the grass straw when you blow into it. Without cupping the hands correctly, the straw would sometimes not vibrate at all, and you’d have to reset the hands to enable it to work. So from this we know that the resonator shape has or can have an effect on the source vibrations.

We generally assume that the passaggio typically exists on certain notes. The dreaded one for males is usually said to be somewhere between F4 and Bb4 depending on voice type etc.

And some singers go as far as being able to tell exactly on what note ‘their’ passaggio sits, or what notes are safe and which ones lie beyond.

However, I think most singers have found that on ‘good days’ their passaggio seems to be higher, and on ‘bad days’ it seems to be lower. So there is certainly a form dependency at play here as well. In good form on a good day higher notes are possible, in bad form on a bad day not.

Next, it’s probably fair to assume that when people ‘test’ where their passaggio sits, that they do this with vowels that lend themselves for singing higher notes with. So they tend to use mostly bright sounding vowels and then assume that because they’re using mostly the same resonator setup to make such vowels, that their passaggio is set at a certain pitch in general. Or they say, that their passaggio sits between notes x and y, which are close together.

So as an experiment, try to determine where the passaggio is when singing in a Father Christmas style.

The passaggio should be much lower than before, and in fact, notes that used to be easy would now seem to be beyond the passaggio. Correct?

We can say then that the passaggio is not fixed at a certain point and that it varies with day to day form, the resonator setup and possibly how the resonator affects the source vibrations.

The impedance of the resonator:

Inside the resonator we are basically dealing with air that’s being moved and compressed. When we move air it needs to accelerate and travel from a to b, that means the mass of the air is relevant. If the mass is large it resists mucho, and this property is called inertia.

When we compress air, we essentially store energy in the compression. The compressed air has a desire to expand. There is resistance because the expansion moves air also towards you. It’s bouncy and this is called compliance.

So, inertia and compliance offer resistances in opposite directions. With inertia the resistance decreases as the air is accelerating. With compliance the resistance increases the more the air gets compressed.

Resonances happen when the effects of inertia and compliance cancel each other out, more or less.

Both, inertia and compliance are frequency dependent. But with compliance, the higher the frequency the lower the resistance.

Yet with inertia, the higher the frequency the higher the resistance.

When we sing we create frequencies along the harmonic series. For each of these frequencies, the vocal tract is resistive. The total resistance or impedance of the vocal tract is then the sum of all those impedances at each frequency.

Depending on how a vocal tract is shaped, i.e. what vowel shape , Father Christmas, Micky Mouse, etc., it has a different overall impedance.

When people talk about impedance, this is usually put into context with flow and pressure. When the pressure is high, flow is also high and vice versa. However when pressure is high and the impedance is high, then flow is low etc.

With pressure it’s important to note that pressure in this context is always a relative pressure, so the difference between absolute pressures at point a and point b is what matters. And therefore flow is measured as from a to b as well, and with that the impedance between a and b can be calculated.

So, a resonance is when the impedance is low and therefore the flow high. Therefore a certain vocal tract shape can offer a low impedance for certain frequencies to enable higher flow or output. Bright sounding vowels are just that, they provide a lower impedance at certain frequencies compared to dark sounding vowels. In fact, with a dark sounding vowel, the overall impedance could be so high that no flow is possible at those frequencies.

When we use twang (slight modification of the vocal tract), we essentially lower the overall impedance of the vocal tract. We can hear that because some of the higher harmonics become louder, i.e. they flow more. Or in other words, we enable a higher resonance (lower impedance) at a certain frequency, which overall lowers the impedance of the vocal tract and thereby enables us to sing higher notes in general.

In order to still sing certain, higher, notes even when a vocal tract setup is not ‘ideal’, i.e. in order to still create flow, we could increase the pressure difference between points a and b by increasing lung pressure (takes effort) or singing on high mountains. (https://www.youtube.com/watch?v=DpJUkzU96Kc) (Listen to the how easy the high notes sound.)

So, to improve how to navigate the passaggio:

– explore the dimensional possibilities of the vocal tract to lower its impedance overall

– develop laryngeal muscles and coordination

– increase lung pressure

– falsetto (develops laryngeal muscle coordination and also lowers the impedance of the resonator at higher frequencies due to the larger opening at the glottis)