Making Sense of Formant Tracking Charts part 1: The Tenor issue and a shoutout to Italian Tenor

Following the commentary from George and Baritonobasso I will work on changing the color scheme and deal with the phonetic/phonemic issue. With this post I wanted to kill three birds with one rock (stone. I used to say rock for years). 1) I wanted to start discussing the formant tracking issues now that we have the charts available 2) I wanted to address the C4 to C5 octave relative to some private talks I’ve had with Martin Berggren 3) I wanted to bring support to a concept that Italian Tenor (a frequent contributor to NFCS) has brought up often, “the deep” [u].

1) A. The first thing to remember about any vowel chart is that it is created with the purposes of the author in mind. Despite a rather broad international experience, my formative musical years took place in the United States. My chart therefore concentrates on the four operatic languages most sung in the U.S. In fact a different chart should be made relative to every national school. Italian and Spanish have 7 vowels-sounds, English 12 German 13, French 14. For Scandanavian Slavic languages and Asian languages, there are vowel qualities that are not represented here. I would welcome charts following our principles here that reflect a more accurate scheme for formant tracking (vowel modification)for those specific languages. Nevertheless the 16 vowels represented on my charts form a full enough spectrum to satisfy most linguistic situations.

B. A vowel chart is a beginning not an end. It should be understood that vowel modification is worthless if the phonation mode is not efficient. Achieving an inertial state in the vocal tract will only have an effect on a lean, muscularly balanced phonation mode. In the best case scenario, a resonant vowel adjustment will yield sensations that the singer will come to recognize and reproduce easily as long as the instrument is healthy. Once the singer has a clear proprioceptive experience of 1st and second formant resonance, then s/he will be able to track formants more spontaneously and instinctively.

2) A. The register shift for the tenor voice is probably the most important issue. Proper execution of this change reflects positively on several aspects of the instrument, including correct muscular balance of the voice, efficient phonation, appropriate laryngeal depth and of course appropriate tuning of the vocal tract (formant tracking). It is important to know that all of these conditions must exist simultaneously in order for a smooth and comfortable register change to occur.

B. The misconception about “pure” vowels. We only need to hear the average soprano sing in her upper range to know that vowels cannot be sung as they are spoken. This is true throughout most of the range. Depending on the circumstance, certain vowel qualities are not possible. In effect, every note has a different resonance necessity and therefore a different formant balance (vocal tract partition/shape). Furthermore there are acoustic regions where more than one vowel intersect. This means that one vowel adjustment will sound like two or even three different vowels depending on context (surrounding consonants, etc). In other words, intelligibility does not mean that someone is singing the spoken form of a vowel.

C. Providing all other conditions are met, the vowel chart can be followed to accomplish the acoustic shift from formant 1 to formant 2 between C4 and C5. The acoustic shift should occur around F4#. Contrary to popular belief, this change does not depend on voice type. Second formant tuning is more appropriate from F4# on, however, a lighter tenor will feel less stress singing a first-formant dominant F4# then a heavier voice. Regardless, the larynx will rise for an F4# sung in first formant dominance. The distinction is that the muscular shift happens earlier for a dramatic tenor than a leggiero, but the acoustic shift happens in the same place. This can get confusing. It suffices to say that the resonance adjustment needs to happen around F4# for any tenor, in fact sometimes on F natural depending on the vowel modification involved. The leggiero who keeps F1 dominance up until A4b like some do will experience a more difficult shift when they finally do go to F2 tuning.

3)Italian Tenor from NFCS has often spoken about the “deep [u]” relative to the tenor high range. According to the chart, Italian Tenor is correct relative to the two notes that define a tenor’s existence. There are more Bbs and B naturals then high Cs written for tenors. Those are the notes that occupy most tenors’ minds. It just so happens that the best second formant vowel for Bb and B is [U], and as previously stated, the larynx must be low to achieve F2 tuning. Italian Tenor’s “deep [U]” is totally consistent with acoustic expectations.

This video of Carlo Bergonzi singing “O Paradiso” from Meyerbeer’s L’Africaine is an interesting example of the deep [U] concept. The first Bb at 1:30 is perfectly tuned. Likewise, the final Bb is tuned to some form of [e] or [ø] very consistent with the tuning of B4b according to the chart. It is important to know that the Italian score (like the French original) has the Bb on an [a] vowel. Bergonzi changed the text setting in the cadenza (traditional practice) to accommodate a more resonant vowel. This means that he was very sensitive to F2 tuning.

By the same token, there is a tendency to make too much of a good thing. Lip rounding as with the deep [U] lowers the first formant and encourages F2 tuning. However, flexibility and subtlety is important. Bergonzi uses the same [U] on the first Gb at 0:49 which sounds comparatively slightly tense until he gently modifies to someting closer to [u]. The same Gb sung on an [u] vowel at 2:07 is perfect. The [u] vowel is far enough from the suggested [Λ], however some form of [u] lies precisely at the formant frequency that would coincide with the 5th harmonic (H5) 930Hz. Bergonzi has a tendency to round the lips consistently. This is not a bad strategy because in the [a] to [u] vowel spectrum, this strategy works well in the passaggio and above. However, more precise tuning is important on certain notes. My studying of Bergonzi’s beautiful voice reveals some difficulties where the rounding lips actually takes him away from ideal resonance. However, on the whole the approach is logical and practical relative to F2 tuning.

Additionally this should show that the chart is a point of departure and not the final word on formant tracking. In the case of Bergonzi, he found a vowel sound between [U] and [u] that coincided with H5 of F4# (Gb in the score). The lesson here is that a vowel spectrum includes many formant frequency pairings for which there is no standard vowel name. Live singing goes beyond the limits of vowel definitions. However, the concept behind the chart can certainly explain something that may appear to be anomalous.

Happy Thanksgiving to all!

© 11/26/2008

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