Harm Schutte

Change in Singing Voice Production,Objectively Measured

*Harm K. Schutte, †James A. Stark, and †Donald G. Miller

Sackville, New Brunswick, Canada and Groningen, The Netherlands

Summary: Although subglottal pressures in conversational speech arerelatively easily measured and thus known, the higher values that sometimesoccur in singing (especially in tenors) have received little attention in theliterature. Still more unusual is the opportunity to measure a large-scalechange over decades in the application of pressure in singing production. Thisstudy compares measurements of subglottal pressure in a tenor/singing teacher(JS) at two points in his career: in his early thirties, when he was a subject inHS’s dissertation study on the efficiency of voice production; and recently, in hisfifties, in connection with JS’s forthcoming book on the history of the pedagogyof Bel Canto. Although a single case study, its points of special interest includethe high values initially measured (up to100 cm H2O) and the reduction of thisfigure by more than 50% in the maximal values of the recent measurements. Thestudy compares these values with those of other singers in the same laboratory(both with esophageal balloon and directly, with a catheter passed through theglottis) and in the literature, as well as discusses in detail the problems pertainingto the measurement (repeatability, correcting for lung volume, etc.).As a sophisticated subject, JS makes some pertinent observations about thechanges in his use of subglottal pressure.

Key Words: Subglottal pressure—Air flow rate—Singing voice—Tenor—Measuring procedure.

Accepted for publication January 30, 2002.Paper presented at the 26th Annual Symposium: Care of the

Professional Voice, The Voice Foundation, Philadelphia, PA,June 1997.

From the *Department of Music, Mount Allison University,Sackville, New Brunswick, Canada; †Groningen Voice Re-search Lab, Department of BioMedical Engineering, Facultyof Medical Sciences, Groningen, The Netherlands.

Address correspondence and reprint requests to Harm K.Schutte, Groningen Voice Research Lab., Dept of BioMedicalEngineering, Faculty of Medical Sciences, Ant. Deusingloan 1,9713 AV, Groningen, The Netherlands. E-mail: [email protected]

Journal of Voice, Vol. 17, No. 4, pp. 495–501� 2003 The Voice Foundation0892-1997/2003 $30.00�0doi:10.1067/S0892-1997(03)00009-2

49

INTRODUCTION

Although subglottal pressures in conversationalspeech are relatively easily measured indirectly,1–3

and thus known, the higher values that sometimesoccur in singing (especially in tenors) have receivedlittle attention in the literature. In general, research-ers have reported subglottal pressures for conversa-tional speech ranging from about 7 to 10 cm H2O,reaching around 10 to 12 cm H2O for loud speech,and about 40 cm H2O for shouting. Some authorshave reported subglottal pressures in singing to reach40 to 70 cm H2O, with the upper limit rarely above60 cm H2O.4,5–9 Furthermore, Schutte has measuredeven higher levels, especially for tenors, who havereached 100 cm H2O or more on high, loud notes.10,11

5

mailto:[email protected]

mailto:[email protected]

HARM K. SCHUTTE ET AL496

The Groningen Voice Research Lab has now hadthe unusual opportunity to measure a marked changein the levels of subglottal pressures in the singing ofone such tenor-subject (one of the authors) spanninga period of more than 20 years. This study comparesmeasurements of the subject, a professional tenorand singing teacher, at two points in his career, firstwhen he was in his mid-thirties and was a subject inSchutte’s dissertation, The Efficiency of Voice Pro-duction (1980)11, and second, when he was in hismid-fifties and writing a book on the history ofvocal pedagogy.12

Although this is a single case study, its pointsof special interest include the high values initiallymeasured, and the marked reduction of this figurein the maximal values of the recent measurements.The subject associates this difference with a deliber-ate change in his vocal technique—a change thatwas based on his interpretation and application ofsinging methods described in certain historical voicetreatises. In this study, we will also discuss in detailthe problems pertaining to the measurements of sub-glottal pressures.

METHOD

In measuring subglottal pressure in professionalsingers, one might encounter a few typical problems,depending, among other things, on the measurementtechnique employed. At present, one can choosebetween five techniques:

I. Direct Measurements

1) Direct measurement by using a needle insertedthrough the cricothyroid membrane has obvi-ous psychological drawbacks for the singer.One would be very reluctant to do this withsingers in the midst of their careers, al-though some important data have been ob-tained in the past by using this technique.13

2) Direct measurement by means of a catheterwith wide-band pressure transducer, which ispassed through the glottis, recording thepressure changes above and below the vocalfolds.14

II. Indirect Measurements

1) The technique of using intra-oral pressuremeasurement, interpolating a value for the

Journal of Voice, Vol. 17, No. 4, 2003

subglottal pressure from a following andpreceding occlusive (/bæp/method after Ro-thenberg15), is routinely accepted for pressuresused in speech, but is questionable for themeasuring of the high pressures singers tendto use15.

2) Using an esophageal balloon: a) while keepingtrack of the changing lung volume during pho-nation; b) The Van den Berg maneuver (ex-plained below). In this study, results are givenof both methods employing the esophagealballoon.

Van den Berg introduced the indirect method,named after him, in 195616. This method is based onan informed application of the principles of lungmechanics. Intrapleural pressure, that is the pressurebetween the pleura blades, is directly related tothe intrathoracic pressure and can be measured bymeans of an esophageal balloon, brought into thelower part of the esophagus. Changes in the intratho-racic pressure and thus in the pressure below thevocal folds during phonation are indirectly measuredin this way. However, changes in lung volume duringbreathing and singing influence the value of theintrapleural pressure. Esophageal pressure duringphonation thus has two components: (1) a negativecomponent, which is a function of lung volume,(the greater the lung volume the larger the nega-tive component), and (2) a further component,tracheal pressure, amounting to the pressure differ-ence between atmospheric pressure and pressure atthe trachea. This second component, also called sub-glottal pressure, is of course positive in the act ofexpiration against any barrier presented by the nar-rowed glottis, or other articulatory structures of thevocal tract. There is a well known relationshipbetween lung volume and esophageal pressure underthe condition of an open airway, and this can beused in distinguishing the two different componentsof the esophageal pressure. The easiest way to moni-tor the momentary value of the lung volume isby measuring the amount of air that is displaced bybreathing. This requires a pneumotachograph, con-nected to either a mouthpiece or a mask, either ofwhich produces an effective elongation of the vocal

SINGING VOICE MEASURED 497

tract and a distortion of its normal acoustic proper-ties. The mask influences at the very least the audi-tory feedback of the singer-subject, who must thencope with acoustic conditions of the vocal tract thatdiffer from the normal conditions of singing.

As the value of the subglottal pressure used insinging tones is simply added to the first (lung-volume dependent) component of the esophagealpressure, a phonation stop at the end of a tonewill reduce the value of the esophageal pressure bythe value of that pressure at the end of the phonation.This is the basis of the Van den Berg maneuver16;however, a proper and well-executed maneuver mustfulfill three conditions: (1) abrupt cessation of theact of phonation, because even a small decrescendowill result in an unwanted reduction of subglottalpressure; (2) maintenance of an open glottis for ashort period immediately following the cessation ofphonation (otherwise intrathoracic pressure reflectedin the esophageal pressure can remain high); and (3)avoidance of inhalation or exhalation directly fol-lowing the phonation stop, because any change inlung volume or transient pressure difference be-tween trachea and outside air will change the valueof the esophageal pressure. Both approaches tomeasuring subglottal pressure using an esophagealballoon (II2a and b) are depicted in Figure 1. De-tailed information on the reliability and accuracy ofthe method can be obtained from Schutte11.

In 1974, the airflow rate was measured to registerthe changes of lung volume. In this way, highlyreliable values were obtained for subglottal pressure.These values were also occasionally checked usingthe Van den Berg maneuver. In 1996, a higher level ofsophistication in experimental procedure, as well asof singing skill, made it possible to use the Van denBerg maneuver exclusively. This avoids the disad-vantage of the elongated vocal tract and its disturbingeffect on the singer’s strategies for optimizing reso-nances. There were in principle no experimental pro-cedural differences in obtaining subglottal pressure.

The only difference existed in the choice of thepitches used in the measurements. In 1974, the mea-surements were aimed at obtaining aerodynamicdata (and calculated efficiency) over the full dy-namic range, divided into steps of five decibels, atpreselected fundamental frequencies (A2, E3, A3,

E4, G4, and A4)11. In 1996, data of subglottal pres-sure were obtained over the whole fundamentalfrequency range in semitone steps for three subjec-tive levels of loudness. The whole range was firstproduced at a comfortable level, then fortissimo, andfinally pianissimo.

To avoid the inherent tendency to adjust subglottalpressure incrementally in adjacent semitones, eachphonation was removed from the previous one bya perfect fifth plus or minus a semitone (see Figure2). The phonation series starts with the G abovemiddle C, and then the middle C is sung. The thirdtone is then one semitone lower than the first sungtone, G-flat above middle C, and then follows Bbelow middle C. This is continued until the lowestattainable pitch is reached. Upward, the series startswith A-flat above middle C, followed by E-flat, aperfect fifth above that tone, then A-natural, and soon, until the highest possible pitch is reached. Inthis way, the singer could concentrate fully on theproduction of a tone of optimal quality, judged byhis experienced and trained ear.

All signals on both occasions were registeredon a Mingograph MT800, eight-channel ink writer,which was also used for monitoring the pressurechanges in the esophagus. In case of an imperfectVan den Berg maneuver or an involuntary increaseof the esophageal pressure due to swallowing, thephonation was repeated immediately.

RESULTS AND DISCUSSION

The results of the measurement series have beendepicted in Figure 3. The 1974 measurements consistof two measuring series, 2 days apart. The data havebeen lumped together, except for the data on G4(392Hz) and A4 (440Hz). Data on G4 (five instancesof phonations) were obtained only in the first session,and the data obtained on A4 (440Hz) show differ-ences due to an indisposition caused by travel fatigueon the first measuring day and will thus be shownseparately.

The 1996 data are depicted by open circles for thepianissimo tones and closed circles for the fortissimosung tones. The measuring points are connected withlines for the whole frequency range. It is interestingto note that the differences in sound pressure levelbetween artistically usable fortissimo and pianissimo



FIGURE 1. A verification of the indirect measuring method registering the changesin the esophageal pressure by means of the esophageal balloon, upon the abruptcessation of phonation, the so-called Van den Berg maneuver, is depicted. For a briefmoment after phonation, the lung volume is kept constant with an open glottis. Thepressure in the esophagus drops to the value pc corresponding with the lung volume atthat moment. The pressure drop delta-p equals ps � pr, which is the sum of the subglottalpressure (ps) during phonation plus a pressure (pr) that equals the product of the viscousresistance and the air flow rate during phonation. The pressure pr is negligible duringsinging, because the flow is relatively low.

tones amounts to no more than about 15 dB, whichis much lower than the usual decibel differencesbetween loudest and softest (threshold) sung tones ina voice range profile (phonetogram)11. It is clear thatpianissimo in artistic singing is not the same asthe softest phonation level. For this reason, we use themusical term pianissimo for this loudness level.At the other extreme of loudness, however, this dis-tinction does not apply, and the upper contour ofthe voice range profile is essentially identical tofortissimo.

The 1974 data do not contain information on all thesemitones over the whole dynamic fundamentalfrequency range, but is restricted to five fundamen-tal frequencies. Together with the 1996 data, theseare shown in Figure 3. Especially for the mid-range fundamental frequencies E3 (165Hz) and A3(220Hz), the softest tone in 1974 is considerablylow in SPL, which also explains the low subglottal


pressure on E3 and A3, approaching the lowest pres-sure for a sustainable tone.

The most salient difference between the data from1974 and 1996 measurements is in the values forsubglottal pressure in the upper part of the range.For the E4 and A4, the 1996 values for subglottalpressure are lower by about 30 cm H2O, makingthe pressures for fortissimo roughly equivalent tothose for the softest possible tones at the earlier date.Even on A3, subglottal pressure is higher by one thirdin 1974. With the exception of A4, the highest pitchmeasured in 1974, however, fortissimo SPL is onlymarginally lower in 1996, in spite of the reductionin subglottal pressure. (The 1974 values for G4, aswell as the “1974a” values for A4, are uncharacter-istically low. They were included in the figure for thesake of completeness, but were deemed aberrant,due to travel fatigue of the subject on the day oftheir registration.)


The attainment of the 1974 sound pressure levelsat the reduced subglottal pressures of 1996 is evi-dence of improved efficiency, the exact nature ofwhich is a matter of conjecture. An undesirable con-sequence of the change in technique is the apparentloss of the ability to produce the highest pitches(those above G4) with an SPL appropriate to highsubglottal pressure. The high SPL and relativelylow subglottal pressure of the “1974a” A4, however,are an indication that the subglottal pressure maynot be the decisive factor in the SPL. In any case, itis evident from the full set of data that the relationshipbetween subglottal pressure and SPL is not a simpleone, and that other factors, such as proximity ofharmonics to resonances of the vocal tract, can playan important role.

PEDAGOGICAL CONSIDERATIONS

The marked differences in subglottal pressures inthe case of our tenor-subject was due to his deliberatechange in vocal technique over a 22-year period,guided largely by his interpretation and applicationof vocal methods described in certain historical trea-tises on singing. At the time of the 1974 measure-ments, the singer was applying the advice of thecelebrated 19th-century Italian voice teacher Fran-cesco Lamperti and his equally famous son, Gio-vanni Battista Lamperti, both of whom seemedto advocate singing with high subglottal pressures.Francesco advocated “holding back the breath, andnot permitting more air [to escape] than is absolutelynecessary.”17 Giovanni amplified this comment bysaying that the breath should be “held back” by strongglottal resistance, resulting in “compressed breath.”This “compressed breath” was the foundation of hismethod18,19. In Germany, at about the same time,Georg Armin (1909) and Rudolph Schilling (1925)developed a theory called Stauprinzip, or “breathdamming,” which pointed to the use of high subglot-tal pressure and strong glottal resistance20,21. RichardMiller has described breath damming as “a techniqueof breath retention through marked sub-glottal mus-cular pressures. The flow of breath is stemmed bythe glottis as a result of muscular tension similarto that experienced in a painful groan or grunt.”According to Miller, this groaning utterance, called

FIGURE 2. Pitch protocol used in this study. See text forexplanation.

Stonlaut, is the primitive power of the vocal instru-ment, and that “a long list of successful Germansingers in this century have given allegiance to it,”including a number of Wagnerian Heldentenore22.Our tenor-subject, whose early vocal training hadbeen based on relaxation techniques with low breathpressures and high rates of airflow, modified histechnique by developing strong glottal closure andhigh levels of subglottal pressure, consistent with theconcepts of “compressed breath” and Stauprinzip. Itwas these higher pressures that were measured inGroningen in 1974. They were consistent withsimilarly high pressures in the other tenor subjectin Schutte’s measurement11, noted that the techniqueof Stauprinzip “has been rejected generally, be-cause it may lead to damage of the voice.” However,Schilling, in 1922, did not categorically dismissStauprinzip, and Schutte concurred that “withoutfurther investigation, this (the high subglottal pres-sure) is insufficient reason to discard this singingmethod completely”11.

Nevertheless, after learning to sing with thesehigh pressures, our tenor-subject became concernedthat he might be generating higher pressures thanwere optimal for his type of lyrical singing. He foundit difficult to execute mezza voce, diminuendo, messadi voce, or other forms of low-intensity singing. Aswell, he characterized the voice quality as “heavy”or “labored,” and lacking in “buoyancy.” He there-fore turned to the treatises of another famous 19th-century voice teacher, Manuel Garcia II, who alsoadvocated strong glottal closure, but with “steady,”“moderate,” and “prolongued pressure.” Garciamaintained that glottal closure should be achievedwith firm adduction of the interarytenoid musclesby “pinching the glottis.” He further maintained that



FIGURE 3. The results of the measurements in 1974 and 1996. In the upper part, thevalues are given for the Sound Pressure Level, measured at a microphone-mouth distance of30 cm. In the lower part, the values for subglottal pressure are given. See text for discussion.

the firm closure of the arytenoid cartilages had theeffect of shortening the vibrating portion of the glot-tis and reducing airflow rates, and gave a bright edge(eclat) to the sound source. Garcia’s vocal methodwas based on the coordination of glottal settingsand vocal tract adjustments intended to “put thesinger in possession of all the ‘tints of the voice”23,24.Garcia’s pupil, Hermann Klein, renewed the call for“compressed breath,” but noted that the singer “mustbe guided by ease and economy of breath pres-sure”25. He said that Garcia’s first rule was to “re-press the breathing power and bring it into properproportion with the resisting force of the throat andlarynx”26. In interpreting Garcia’s advice, our tenor-subject again modified his technique, this time byreducing the subglottal pressures while maintaining


strong glottal closure. The Groningen measurementsof 1996 confirmed the reduction of both subglottalpressures and airflow rates compared to the 1974measurements. In the singer’s opinion, this was ac-complished by consciously reducing the degree ofcontraction of the expiratory muscles during singing.The chief vocal exercise used to achieve this wasthe messa di voce, that is, the crescendo-decrescendoof a long note.

CONCLUSION

What seems to us remarkable in this study is thedegree to which the subject was able, through con-scious application of a principle, to change sub-stantially the levels of subglottal pressure used


habitually in singing. The high levels of the 1974measurements resulted from a singing technique ac-quired deliberately, and the reduction reflected inthe 1996 measurements was equally the result of adeliberate change. The fact that SPL was only af-fected marginally by the reduction is also remark-able, considering that subglottal pressure is generallyrecognized as the controlling factor in vocal loud-ness. Finally, the fact that this subject was able,without damage to his vocal folds, habitually touse pressures in singing that many authorities mightconsider excessive (eg, Proctor, who regards 25 cmH2O as unusually high pressure in singing) is anindication that singing methods advocating high sub-glottal pressures (eg Stauprinzip) are not necessarilyphysiologically detrimental.

REFERENCES

1. Rothenberg M. The Breath-Stream Dynamics of Simple-Released-PlosiveProduction.Basel,Switzerland:Karger,1968.

2. Rothenberg M. Interpolating subglottal pressure from oralpressure. J Speech Hear Dis. 1982;47:219–220.

3. Lofqvist AG, Carlborg B, Kitzing P. Initial validation ofan indirect measure of subglottal pressure during vowels.J Acoust Soc Am. 1982;72:633–635.

4. Netsell R. Subglottal and intraoral air pressures during theintervocalic contrast of /t/ and /d/. Phonetica. 1969;20:68–73.

5. Proctor DF. Breathing, Speech and Song. Vienna, Austria:Springer-Verlag; 1980.

6. Khambata AS. Anatomy and physiology of voice produc-tion: the phenomenal voice. In: Critchley M, Henson RA,eds. Music and the Brain. London: William HeinemannMedical Books; 1977:59–77.

7. SearsTA. Someneural andmechanical aspects of singing. In:Critchley M, Henson RA, eds. Music and the Brain. London:William Heinemann Medical Books; 1977:78–94.

8. Wyke BD. Ventilatory and Phonatory Control Systems.London: Oxford University Press; 1977.

9. Baken RJ, Orlikoff RF. Clinical Measurement of Speech andVoice. San Diego, CA: Singular Publishing Group; 2000.

10. Catford JC. Fundamental Problems in Phonetics.Bloomington, Indiana: Indiana University Press; 1977.

11. Schutte HK. The Efficiency of Voice Production. 1980.Thesis University of Groningen.

12. Stark J. Bel Canto: A History of Vocal Pedagogy. Toronto,Canada: University of Toronto Press; 1999.

13. Rubin HJ, LeCover M, Vennard WD. Vocal intensity: sub-glottic pressure and air flow relationships in singers. FoliaPhoniatrica. 1967;19:393–413.

14. Miller DG, Schutte HK. Characteristic patterns of sub- andsupraglottal pressure variations within the glottal cycle. In:Lawrence VL, eds. Transcr XIIIth Symp Care Prof Voice.Part I: Scientific Sessions. New York: The Voice Foundation,1985:70–75

15. Rothenberg M. A new inverse-filtering technique for deriv-ing the glottal air flow waveform during voicing. J AcoustSoc Am. 1973;53:1632–1645.

16. Van den Berg Jw. Direct and indirect determination of themean subglottic pressure. Folia Phoniatrica. 1956;8:1–24.

17. Lamperti F. A Treatise on the Art of Singing. New York:E. Schuberth; 1871.

18. Lamperti F. The Technics of Bel Canto. New York: G.Schirmer; 1905.

19. Brown WE. Vocal Wisdom: Maxims of Giovanni BattistaLamperti. New York: Taplinger; 1957.

20. Armin G. Das Stauprinzip oder die Lehre von dem Dual-ismus der menschlichen Stimme. Strassburg: Carl Bongard;1909.

21. Schilling R. Untersuchungen uber die Atembewegungenbeim Sprechen und Singen. Monatsschr Ohrenheilkd Laryng-orhinol. 1925;59:51–80,134–153,313–343,454–467,643–668.

22. Miller R. English, French, German and Italian Techniquesof Singing: A Study in National Tonal Preferences and HowThey Relate to Functional Efficiency. Metuchen, NJ: TheScarecrow Press Inc; 1977.

23. Garcia M. Traite complet de l’art du chant. In TwoParts. Paris: Chez l’Auteur; 1847. Reprint ed. Geneve:Minkoff; 1985:Part I:24; Part II:18–21.

24. Garcia M. Hints on Singing. New York: The Joseph PatelsonMusic House, 1982. Translated from the French by BeataGarcia. New and Revised Edition. Hermann Klein, editor.London: E. Ascherberg. 1984:13, 22.

25. Klein H. The Bel Canto, with Particular Reference to theSinging of Mozart. London: Humphrey Milford, OxfordUniversity Press; 1923:21–24.

26. Klein H. Thirty Years of Musical Life in London, 1870-1900. London: Heinemann; 1903:36.


Documents

Harm Schutte