Friday, October 31, 2008

Spontaneous Formant Tracking: A point of logic Part 2

The C4 to C5 region is of particular interest to baritones, tenors and women. Before we continue with formant tracking with respect to these voice types, it is worthwhile to outline once again certain basics:

1. Definition: Formants are acoustic frequencies bands covering 30-50 Hz of acoustic space, which, depending on their range, define what we hear as vowels.

2. The vocal tract works better when its reactance is inertial. Simply put, this inertial state of the vocal tract helps maintain efficiency at the glottis even when the folds barely touch. This inertial state depends in large part upon formant tracking. The vocal tract reactance is inertial when the formant is above the corresponding harmonic of the standing wave (fundamental pitch and all its harmonics is referred to as the standing wave). We have our good friend, Martin Berggren to thank for this important detail.

3. Four Rules for Modifying Vowels

A. All formant frequencies decrease uniformly as the length of the vocal tract increases

The vocal tract length increases when the larynx lowers.

B. All formant frequencies decrease uniformly with lip rounding and increase with lip spreading.

Lip rounding and lip trumpeting have the same effect (see details on the NCVS page)

C. A mouth constriction lowers the first formant and raises the second formant.

This includes the raising of the tongue principally as in going from the [a] to the [i] vowel whereby the space below the tongue increases (lowering the pitch. Larger spaces have lower pitch) and the space above decreases (raising the pitch. Smaller spaces have higher pitch).

D. A pharyngeal constriction raises the first formant and lowers the second formant.

The reverse of letter C.

In order to follow these rules, we must establish what the default position of the vocal tract should be. I proceed from the following:

The larynx cannot fall to its naturally low position without the jaw being released. The laryngeal position that produces accurately resonance notes in the speaking range (male between 110 and 150 Hz and women between 220 and 260 Hz) should be the default. Therefore:

1. The larynx should maintain that basic low position.
2. The jaw should always return to the [a] position and the tongue and lips should articulate for all changes (consonants and vowels).

If the jaw had to close for vowels and the larynx had to rise, the variables would be too many and since both would narrow and shorten the larynx, the voice would have a thinner quality.

The key to good resonance is establishing healthy phonation and a "natural" resonance space. By natural I mean that the most comfortable laryngeal level must be accomplished. It is just as unproductive to sing with a depressed larynx (forced too low by tongue depression) as it is to sing with a raised larynx (usually from pressed voice, i.e. excessive medial pressure resulting from inadequate sub-glottal pressure).

Assuming that phonation is normal, the resonance strategy should happen as follows:

Modify the vowel as close as possible to the given vowel while tracking the appropriate formant that would render the vocal tract inertial.

1. It is important to figure out which formant (first or second) is the easiest to tract (i.e.
without raising the larynx and requiring the least migration from the given vowel. There
are two reasons for maintaining a naturally low larynx: A) a long vocal tract tends to be more
inertial. B) A longer vocal tract reinforces lower partials, necessary for balance of chiaroscuro
by not losing the natural darker colors of the voice (particularly important for voice types
requiring more dramatic colors).

2. The frequency range of the formant must be above the respective harmonic in order
for the vocal tract to be inertial.

Following these basic principles, the rest becomes a matter of logic. It is also important to understand that the other three upper vowel formants can also have a profound influence. By concentrating on the first two formants (because we have definite information on what influences them) we can accomplish the inertial state that we refer to as "resonant." Once the singer becomes familiar with the feeling, it becomes easy to track it. Habits begin to form and the process of vowel modification (resonance tracking or formant tracking) becomes practically an instinctive one. This is the goal! The science only gives us a path to experiencing what true resonance is. The refined product is a personal experience and should seem quite natural in the end.

Looking at the /a/ formant chart for C4-B4, we can make some clear decisions relative to the lower passaggio and middle range of women and the middle to high range of men. What is difficult to understand sometimes is that the acoustic choices can be the same for baritone and tenor or soprano and mezzo in the Eb4 to G4 range. A tenor is perfectly capable of tracking F2 on Eb4 for the /a/ vowel. However, the modification would sound extreme because the voice does not sound very stressed on Eb4. The operatic ear accepts vowel modification where the longitudinal tension (tension along their length) on the folds is high. It is perceived that a modification is made to relieve excessive tension (good formant tracking does). A speech-like (F1) non-resonant Eb4 in the tenor voice may sound more "natural" to the average listener than a covered (F2) resonant version because the F2 version requires too much vowel modification for a note that is easy for that voice type. The same note sung covered by an baritone or bass sounds acceptable to the traditional operatic ear. The same may be unacceptable to a musical theater audience who expects speech-like vowels throughout the range. The most important fact we should know relative to resonance strategy is the following:

Although formant frequencies in the F1 region coincide with the lower modal voice (vocalis-dominant) of the male singer and F2 frequencies with the upper modal voice (CT-dominant) in traditional classical singing, formant choices are not absolute. They depend greatly upon genre and style. It is crucial that we do not make the error of making resonance tracking the magic pill for vocal imbalance. Vocal imbalances have a muscular component that is quite independent of acoustic strategy. When the muscular aspect is correct, good acoustic strategy can have a substantial refining effect. The same can be said relative to the female acoustic passaggi.

In the modal range (vocalis and CT both active; what we call the real voice) we deal with a two register muscular modal distinguished by vocalis-dominance on the lower end and CT-dominance in the other. Both male and female voices behave this way, with approximately a one-octave differential between bass and contralto, baritone and mezzo, and tenor and soprano respectively. The modal range covers a little more than two octaves for each voice type. F1 dominates approximately in the lower three-fourths of the male range in the operatic context and F2 takes over in the upper one fourth. For tenors the ratio might be two thirds to one third. In the female voice the ratio is more complex. Because vowel formants are pitch-dependent, there are two formant changes in the female modal range. Roughly one fourth F1-dominance in the chest range, two fourths in the middle range and one fourth in the head range. In short, the male and female voice behave the same muscularly but radically different acoustically because of the octave differential.

This installment Spontaneous Formant Tracking has been long coming, and so I will publish it. The third installment will follow and will address specific strategies for each voice type. I would like YOUR help in the third installment. Please send me requests relative to specific arias or songs that give you trouble, or that you feel could be better addressed. I will analyze the situation and find solutions based on the premises we discuss here. In fact, I would be interested in clips of you singing the phrase in question. I will analyze it acoustically and consider muscular balance as well. I will send you recommendations and see what happens afterwards. I think this would help us all understand the issues we are dealing with.

Happy singing and Happy Holloween!

© 10/31/2008


thetruth said...

What exercises would you recommend to keeping voice in its "real voice"?

For the most part,well to me, it sounds like my talking voice and my singing voice sound very much alike..Is there a such thing as over thinking singing? Cause I think my biggest downfall is when Im joking around, I can execute a lot of different notes and when im constantly thinking of the note and the pitch that its supposed to sound like and as soon as it sounds the slightest off, It kills my mood lol and then I find myself thinking it all sounds bad.

It could also be my idols where I draw inspiration from, though highly original, It seems as If I cant take it and mold into something different in my voice but Im mimicking those sounds. BTW I SENT U AN EMAIL A WHILE BACK, DONT KNOW IF U GOT IT BUT I SENT THE VIDS I SAID I WAS GONNA SEND.


Toreadorssong's Vocal Technique Blog said...

Could you send the vids again. I did not get them. As for exercises, the real (modal) voice depends upon an interaction between vocalis and CT. The fact is that the middle voice tends to involve both sets of muscle. The issue relative to modal voice is whether the singer can keep a modal coordination near the extremes. Young tenors have a tendency to sing falsetto in the upper end because they lack the strength and coordination to find the proper vocalis activity. Sopranos and mezzos often to to a pulse (fry) range too soon in the lower range because they lack the CT strength and/or the vocalis control to have just the right balance to produce a coordinated low range. It also takes a teacher who can hear the difference as soon as it happens and bring the students sensitivity to it. The exercise is simple. For the low range (the balance is significant for men as well)sing a clear (not pressed not breathy) tone at mp one octave from the lowest note which will tend to be modal. Bring this quality down in a five-note scale attempting to maintain the phonation quality of the middle voice. On the bottom note, crescendo carefully without going into fry quality (open chest voice). The reason we want to keep the volume soft at first is that if there is lack of strength in the CT, the increased sub-glottal pressure will make it buckle and the tone will become totally vocalis dependent. Pitch depends on the product of mass, length and tension of the folds. There are several ways that a given pitch can be configured. By getting the right muscular coordination it is possible to accomplish a modal (real) sound close to the bottom of the voice.

For the top, begging just below the passaggio also at mp and do a five note scale up and down slowly. Sustain the top note and crescendo slightly avoiding the tension that is potential if the CT is stressed beyond its ability to handle sub-glottal pressure. Volume is a big determinant of balance. Good balance becomes stronger over time. Imbalance also becomes stronger over time. That is why, it is crucial from the first moment that principles of balanced phonation be applied, even when the results are not immediate (due to weakness in certain muscles and/or hyperactivity in others.

thetruth said...

do you have an alternate email address, maybe a yahoo one? ive sent it twice to ur google lol.

Toreadorssong's Vocal Technique Blog said...

You may also send it to or

The problem may be in the spelling: (one r two ss)

Blue Yonder said...

This has really been an information-packed post, AND it turned me on to the NCVS tutorial page, which I subsequently spent some time reading.

Here is one major barrier I face in understanding formant tracking and resonance in general: I've read the terminology (thanks to you!), but I don't know what to listen for, since I don't know how the terminology translates into what my ear hears. Can you point me to any video/audio clips of what different resonance tracking strategies sound like (including the bad ones) for both men and women? I'm also interested in hearing what it sounds like when a male or female singer move back and forth between F1/F2 while negotiating a line in that tessitura.

Any help you can provide in teaching my ear to recognize formant strategies and resonance vs. non-resonance is greatly appreciated!

Toreadorssong's Vocal Technique Blog said...

Dear Blue Yonder,

Thank you for your excellent comment. I am working on a more complete post relative to vowel charts and formant tracking. I will work also on a post dealing specifically with hearing formant changes with examples for both men and women. The changes are generally more subtle in women than they are in men. For starters, listen to Pavarotti explain the acoustic change from F1 to F2. Phonation remains more or less constant but the resonance changes. He begins his explanation at 3:15.

At 5:00 Marilyn Horne demonstrates clearly the F2 to F1 and then to F2. That is F2 down to F1 and then back up to F2 range. Notice that she rounds the vowel in the lower passaggio just as Pavarotti does when he demonstrated the "cover."

Derek said...

Toreadorssong- Thanks so much for your excellent blog. I've been reading for a while and also follow your tech posts on NFCS with great interest (sadly I'm now in China and can't access forums here). I'm just beginning to wrap my head around all these vocal science concepts, but what I do understand has greatly helped me in my own progress.

I have specific questions about [i] vowels (which are still what give me the greatest grief) and formant tracking- do you happen to have a chart like you have for [a]? I think I understand the concepts you talk about for [a] as you have laid out in the various posts about formant tracking, but am having some difficulty in applying that particularly to front/high-front vowels.

Thanks for all the great posts~

Toreadorssong's Vocal Technique Blog said...

Hello Derek,

Glad the /a/ chart has been helpful. I am preparing the next post and will include charts for /i-I-e-E-ae/. I hope to have it up by the middle of the week.

Warmest Regards and thank you for your comment.


ramos_troy said...

JRL, to achieve inertial reactance in the vocal tract, I think you must have meant that the formant should be slightly below the harmonic being tracked, not above it. In fact, this is exactly what was illustrated in your C4-B4 vowel formant chart.

For example, to track H3 with F2 on the note D4, one ought to modify toward an UH (cup). But as you can see from your chart, the H3 is at 1200 Hz, while the F2 of UH is around 1190 Hz which is slightly below H3.

~~~ Troy :-)

Toreadorssong's Vocal Technique Blog said...

Dear Troy,

Your comment is timely. I just corrected the vowel charts (two charts, one for front vowels and one for back). The old charts did not consider inertial reactance but rather proximity to the harmonic in question. The new charts reflects this new information. Thank you very much for your comment. A long awaited post will come out today.