Cambio nello squillo – a change in Singer’s Formant

My father passed away with an unresolved mystery when it comes to technique.  We would spend hours listening to Caruso and Bjoerling, talking about what it was in their high notes that was different.  What made their squillo, the high ringing quality, or Singer’s Formant different?

Years ago, I started to train myself to actually hear the harmonics in my voice and learn how to strengthen them.  I started to hear things in recordings of my favorite tenors that I could never quite put my finger on before. I tried to crack the mystery my dad and I never resolved together.  I could hear that the ringing quality of the high notes of tenors from before the 1940s was different than that of their modern counterparts.  I would attribute this to recording equipment, to changes in overall approach, but I really couldn’t figure what exactly I was hearing.

I found the solution thanks to reading the writings of Richard Miller.  In his books, for the first time I saw a representation in graphic form of the harmonics in the voice of some of my favorite tenors; and I noticed very clear differences when it comes to what in Italy we call “squillo” –  Singer’s Formant

Being the science geek that I am, I found and figured out a way to use software to isolate the sounds of these harmonics; and that is when I found that halfway through the 1900s a shift in tenor vocalism occurred in the approach to resonance. 

Singer’s Formant

The high ringing overtones of the tenor high voice, can be significantly strengthened when certain conditions are in place.  I am not going to go into the science of this, but will say that when the voice is efficiently produced, or when the sound is very focused, and when the larynx is relaxed low, and the throat is relaxed and in a yawn position –  the squillo, or Singer’s Formant, eventually can develop.  As the tenor’s ability to sing with appoggio increases, the squillo gets stronger.

I like to think of this Singer’s Formant as a little microphone implanted in our throats that picks up and amplifies only sounds between 2,300 hz. and 3,500 hz.  Now to my point… The tenors in the early 1900s, and a handful after 1940, all enhanced the lower part of that 2,300-3,500 hz range.  Typically the harmonic strengthened was the 5th.  Tenors after the mid 1900s amplified the upper part of that frequency range, usually the 6th and 7th harmonics.  What this means is that the ringing squillo of tenors from the early 1900s was lower in pitch compared to those that came after.

Finally I had figured out what I was hearing.  Caruso’s and Bjoerling’s squillo was a lower pitched squillo compared to tenors like Pavarotti, Corelli, Tucker, Del Monaco, and others.  Here is a clip where I compare two titans: Corelli and Lauri Volpi, two great Manricos from different times.  I will show you the different pitch enhancement of their squillo.  Corelli’s ring is higher pitched compared to Lauri Volpi’s.

Comparison Corelli Lauri Volpi Singer’s Formant

Here are graphs showing what you hear.

Corelli 6th Harmonic Enhancement

Lauri Volpi - Di Quella Pira, 5th Harmonic

The difference in the pitch of their squillo confers different qualities to the sound.  The modern tenors are a bit brighter sounding, while the old timers have more of a dark velvety sound.

For a very long time I tried to understand how to get to the 5th harmonic enhancement like Bjoerling and Caruso had.  I could not.  I tried singing more toward an OO, like they do, to see if the vowel would track the harmonic, but I still could not get it. I kept strengthening the 6th and 7th.  Many modern tenors singing  an OO vowel continue to enhance the 6th and 7th harmonics.  Why wasn’t I able to do it?

I will just give you the answer of many years of study… (1) I carried too much chest voice up, and (2) I had not yet developed the OH-EH mix – voce magra phonation, and (3) I was singing with canna aperta.  Think of the sound as having a sort of tube going through the larynx and up to the mask.  This tube can be wide (canna aperta) or it can be narrow.  If you sing the passaggio in an OH-EH mix in thin voice, and you keep ascending toward the top, aiming to continue the forward ringing quality of the passaggio.  The air feels like it is moving through a narrower tube in the throat.  It’s not a muscular tightening, or at least I don’t think so.  It feels like the space where the air passes through is narrower, but the throat is not constricted.  It is as though the sound were pressing inward toward the larynx. The sound is squished, not the throat.

If you cough gently, you feel where your vocal folds are. When one sings with the OH-EH mix in the passaggio, the tongue is oriented forward, and my sense is that the tongue is not pressing on the larynx.  The OH-EH mix really narrows the sound in the passaggio, and the voice feels like it is striking the maxillary sinuses. It’s a feeling of really thin edge.  If this position is taken up past the passaggio without changing, and the lips are brought forward, the sound will strike more toward the frontal sinuses and the cheeks.  But remember, that is the consequence and not the cause.  You can’t force your voice to go there.  It goes there because of the way the cords are working… it is the thin cry, the tongue forward thanks to the OH-EH mix, and this narrowing of the vowel.  The sound is now compressing inward toward the larynx.  It feels like the voice has reduced the width through which the air can pass.  The voice compresses, not the muscles… The vowel gravitates toward an OO because of this narrowness.  You can sing an AH if you want, but if your sound is narrow, it will come out OO. 

Here is my humble attempt at imitating Caruso, and I am able to tune the 5th harmonic here as I imitate him. 

Comparison 5th Harmonic Caurso-Li Vigni

These are the graphic readouts for the Bflat in La Fleur from Carmen, with Enrico Caruso and my humble imitation.  You will notice from the graphs that the 5th harmonic is particularly strengthened; and also a quick drop of harmonic intensity occurs after the 6th harmonic.  The result is a very compact sound with very little higher, noisier harmonics. The sound is not as bright, but the ring is intense.

Caruso Bflat 5th Harmonic

Li Vigni Bflat 5th Harmonic

Caruso’s vowel is very pure!!!  It’s absolutely, perfectly efficient because the thin voice is balanced with the breath pressure so exactly as to produce a completely efficient sound.  Compared to my attempt, Caruso, besides having an infinitely better quality voice, also has stronger squillo.  I suspect he is able to harness the breath with thin cords much more effectively.

Here is Del Monaco.  You will notice very powerful squillo, but as you can see from the graph, his power is in the 6th and 7th harmonic, and not in the 5th.

Mario del Monaco-Musica proibita 6th Harmonic Dominance

Del Monaco 6th Harmonic Dominance

 Here is Gigli singing the B natural from Pazzon Son, Manon Lescaut.

Gigli_pazzo 5th Harmonic

Gigli 5th Harmonic

Bjoerling 5th Harmonic Dominance

… and last, but not least, let me compare two high notes, one by Caruso, and another by Tucker.  Both have powerful squillo, but as you will hear in the clip, the harmonic being enhanced is different.  Caruso enhances the 5th and Tucker the 6th.  Why the difference in harmonic selection?

Comparison A Natural Caruso – Tucker

Li Vigni – Ou se divine la presence, High C – 5th Formant Dominance (old school if I may say so myself)

The lower harmonic selection requires:

  1. cry mechanism, less chest voice
  2. a continuation of the OH-EH mixed vowel intention (notice Caruso’s note right before the top. It is a perfect OH-EH mix)
  3. compression of the vowel vibration inward toward the cords, or feeling of narrowing of the imaginary tube through which the air passes through the larynx… the sound squishes the space inward toward the larynx.

The Higher harmonic

  1. carries more chest upwards
  2. has a wider imaginary tube through the larynx
  3. the sound leans into the larynx more
  4. the soft palate is pulled upward very much

The secret of the older high note sound lies in not letting the compression of the sound stop the air.  While the secret to the other is to think very much open throat sound.


35 responses to “Cambio nello squillo – a change in Singer’s Formant

  1. This is an amazing post. And I know some people might sneer at “imitating” singers like Caruso, but I remember when you visited Amsterdam and imitated Corelli – you do have a talent for tuning your voice very precisely and I remember being shocked how well you imitated Corelli. I can clearly hear you are hitting the high note exactly like Caruso(albeit with YOUR voice).

    This is very interesting stuff! Do you think favoring higher squillo harmonics may have correlated with higher pitch tuning?

    Also, how would you think this more velvety sound with lower squillo harmonics, yet very intense, would fare in today’s theaters with today’s orchestras? (As compared to voices today).

    Also I am wondering, does Joseph Calleja have the old school squillo tuning too? Does Roberto Alagna have the modern one?

    • Tuning the 5th harmonic rather than the 6th and 7th is not about pitch tuning. This is why I posted the Caruso-Tucker comparison. They are both singing A naturals… even though the Caruso clip is a little fast. This is not about pitch. The old timers from A natural upward strengthened the 5th harmonic across the board. I haven’t found one exception in famous tenors.
      As to the issue of orchestras, they would do just fine. An example of this is Fisichella who is a 5th harmonic singer and can be heard just fine. Surprisingly, and this may shock you, Giacomini has a big 5th harmonic peak, associated with an equally strong 6th – and dominant 2nd formant. Perhaps this is why his voice is so powerful and loud.
      I thought of Joseph Calleja during this study too. For example, his La Donna E’ Mobile B natural is 2nd formant dominant, and then has almost equal strength between 5th and 6th harmonics. Alagna has no particular dominance in the squillo but is pretty even. Florez is 6th and 7th harmonic dominant.
      What do I gather from this? For example, Giacomini shows us that carrying too much chest does not stop you from tuning the 5th. But Giacomini is very pressurized. Caruso is definitely lighter. Giacomini is also very powerful in the higher harmonics, while the old timers have weaker harmonics above the 5th.
      There is probably much more to this puzzle than I am aware of, but I think I understand it pretty well. The issue for me is how to make the 5th a dominant harmonic. The steps I outlined are a sure path.

      • “Tuning the 5th harmonic rather than the 6th and 7th is not about pitch tuning.”

        “This is very interesting stuff! Do you think favoring higher squillo harmonics may have correlated with higher pitch tuning?”

        I know that, sorry for being unclear. What I meant, in light of recent discussion on higher pitch tuning that occurred in the last century, where middle A was put on 440HZ, I wonder if the modern approach to the top correlated with that, as you wrote in your post that it sounds “brighter”:

        “The modern tenors are a bit brighter sounding, while the old timers have more of a dark velvety sound.”

        I didn’t expect that about Giacomini indeed!

        • My personal feeling on the matter is that with the expansion of the middle voice that came with Caruso, it was a natural consequence to try to expand that open throat, wide feeling, also to the top. Hence, we the advent of the true 2nd formant dominant tenors. I believe Pertile was the daddy to all that, but there were others. By the end of his career, Merli sounded like Giacomini does now… there was a real revolution in vocalism, and I believe it was due to the expanding middle voice and the way it fed a different top voice. People like Melocchi sought for “maximum opening of the throt” which means, wide sensation of this imaginary tube I am talking about.
          It’s a good observation about orchestra tuning, and I would add also volumes. Orchestras are huge today. I remember singing a lighter role in Germany and thinking “Holy Cow, this is Wagner…” You have to compete, and its both squillo and lower harmonics that need to be enhanced, and the modern approach to tenor vocalism allows that. You know after all, singers like Beczala, whom I absolutely love, are not that dissimilar from Bjoerling, but you won’t hear Beczala singing Manrico any time soon. Why? Because his approach is too lyrical… He is not going to sacrifice his line to seek greater volume to compete with these monstruous, luscious sounding symphonic orchestras…

  2. I have another question: would you say one or other method of singing high notes is harder? Does one face different challenges? What about the impact on stamina? I would say the “modern” approach, since it requires more chest, may impact stamina negatively?

    • I think the older method makes the voice more directional. Typically, except for some exceptions, the 5th harmonic singers did not have dominant 2nd formant on top, but rather had pretty equal harmonic strength, except for that one peek in the 5th. This means the voice comes at you like a laser, but when they turned around in the theater, the voice drops in intensity (loudness). Singers that are strong in the 2nd formant, like Corelli, Pavarotti, and modern singers, have both the squillo, and also the powerful 2nd formant dominance, which makes them loud even when they are not looking outward all the time.
      I don’t think one is harder than the other, per se. I think they both require a lot of stamina. But the older way is lighter in the throat… it is based on a lighter mechanism, and isn’t as loud in the house, I think.

  3. I don’t find any sound file for “Caruso – Li Vigni, Bflat, 5th Harmonic.”

  4. @Milesrind

    I downloaded it!

    Another question: what about voices like Merli and de Muro Lomanto? I feel De Muro Lomanto had some kind of odd combination of quite obvious thickening up top(more chest) yet still it sounds absolutely “old school”?

    Also, is the Gigli we hear on 20’s recordings the Gigli we hear in 40’s recordings when it comes to harmonics?

  5. There is no sound file linked for the caruso-livigni comparison, nor is there a link to the tucker-caruso sound file.


  7. This is definitely the analysis that we need to have. Upon listening to the Corelli-Lauri Volpi comparison we hear a noticeable difference in formants. Indeed in this case, the vibrato of Corelli is faster than that of LV. LV seems to be under pitch, but is he? The vowel seemingly the same in approach, so it must be something different. I think that you analysis is heading in the appropriate direction. Franco seems to have more frontal resonance, as did Del Monaco and Tucker.

    I would be curious to hear/see the differential on the italian “i” sound, is it is a frontal vowel which possesses great squillo potential in the upper register. I have always been interested in Caruso’s method and have spent years trying to dissect his technique. If you listen to the old lp’s you get a greater sense of his squillo and point. The breath will go from a “wide” position to an immediate point seemingly at will, and at the most appropriate of times.

    There were two things that I came away with:

    1) I’ll never be able to sing like him;
    2)His breath always preceded the notes, and as he ascended he knew when to “release” to set himself up for the money note. This release was seemingly a momentary suspension of the facility with the breath staying in motion, hence, the ability to sing on the “cry.”

  8. I remember listening to the old LPs… nothing quite like em. Yes, Caruso’s voice was incredibly resonant! I think you are right about Caruso… it did go from wide to extremely focused very fast. This is because of the vowel compression.

    Just the other day I had a great email discussion with Steven O’Mara, who is also a 5th harmonic singer when he wants, or a 2nd formant dominant singer when he decides. I think much of the change has occurred because of the volumes of orchestras.

  9. This is Caruso’s E lucevan le stelle that has been restored in a way just a few other recordings can approach. It’s one of the most clear recordings of him. The squillo is jaw-droppingly strong.

  10. Here is my question: how does one adjust the voice to manipulate specific harmonics for the desired effect? What is the exact process involved, phonation?

    • Clarification: which part of the mechanism allows for freedom of balanced phonation thus allowing a singer to manipulate his/her harmonics at will?

      • The whole thing. I’m sorry if that sounds flippant. It is not meant to be. It’s the truth. There is no single part. It’s the whole thing working together. The part collaborate in different ways to produce various effects.

        • You are not sounding flippant!

          Of course balanced phonation is a symbiotic process, but understanding how to manipulate specific harmonics is a completely foreign concept to me. If singer X can fluctuate between dominant 6th and dominant 5th at will- how does he/she accomplish this? What makes the difference sonically speaking?

          • There are some definite points. For example, singing the high note in a modern way is bringing up more chest, which will equate to more volume in the house. This means there is a deeper sense of resonance in the pharynx along with the mask. The imaginary tube passing through the larynx is much wider and the sound is not as concentrated forward, but feels strongly in the back of the head as well, like a soprano would. This is because these sounds are typically 2nd formant dominant ( and the 2nd formant harmonic for the tenor feels more hollow in the larynx and strikes the back of the head – the space above the soft palate – along with the mask). That set up generates typically 6th and 7th harmnic strength in the Singer’s Formant region. The narrower tube singing as I described in the post generates 5th harmonic strength. I find the OH-EH mix triggers this narrowing easily.

  11. It seems to me the ones who tune to the lower harmonic also are the ones who could diminuendo high notes easily when required. Do you think this is due to the headier mix? Also they tend to have continued singing longer.
    Are you sure it’s not actually easier and conducive to a longer career to tune the old fashioned way?

    • I am afraid it is not so cut and dry. It is perfectly possible to push while tuning the 5th harmonic. Many of these tenors, including Caruso, Gigli, and others could not really diminuendo high notes from full voice easily.

      I don’t know that singing this way is less stressful on the larynx. My hunch is that it probably is.

  12. Now that you know how to do both types of high notes, which do you choose in performance?

    Also, that harmonic isolating thing you’re doing is really cool. After hearing it isolated and then hearing the original phrase you can really hear the harmonic clearly. Is this a program you can share? I’d like to train my own ear using this approach. Or do you use an equalizer that’s part of a standard audio program?

    • Certain repertoire instinctively pulls me toward a modern aesthetic. If you listen to my recordings, I am almost always lean toward a more modern approach. However, I have recently decided that I am going to try performing the older way, just because I want to get a feel for it and see how effective it all is for me.

      I recently was speaking with Maetro O’Mara, who is a wealth of knowledge, and he was telling me how singing the older which (which he does often, as his high notes are often 5th harmonic tuned) does not pack the same punch in terms of volume IN THE HOUSE. You have to have a sensitive conductor in order to sing that way and not get squashed by relentless orchestras.

  13. I’ve been thinking about this post for over a week now, and recording myself and making adjustments to see their effects. Incredibly thought-provoking, thank you.

    I’m noticing that I tend to have an even higher harmonic than the 6th reinforced in my own high notes. For example on A or Bb on an “ah” I am getting some strength on H6 and H7, but the biggest peak in the SF range is H8.
    My H1, H2, and H3 are laddered correctly, with H3 being dominant and H2 sitting between it and H1.
    Do you have any ideas why this might be the case? I have a lyric weight voice.

    • Short of hearing you I can make a guess. I think that on A natural, your H8 is right on the edge of the frequencies the Singer’s Formant would normally pick up… being around the 3500 Hz. However, a lifting of the larynx could shift all the formants higher. The fact that your H8 is your strongest peak in the singer’s formant to me suggests that you may be singing in a speech level way, which makes the voice (as I woud say) quackier. Though you might have sufficient release to trigger a 2nd formant dominance, the high SF range seems way too bright… “witch voice” exaggeration? Hmmm… send me a clip.

  14. Jack,
    You said that “The high ringing overtones of the tenor high voice, can be significantly strengthened when certain conditions are in place.” Is that exclusively the “high voice” or can the middle and low ranges be “strengthened?”

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