The Science of the Singing Voice

Overview of the course

Winter 2006

Books

• Johann Sundberg, The Science of the Singing Voice. Northern Illinois University Press (1989)

• Peter Ladefoged, Elements of Acoustic Phonetics. Second edition. University of Chicago Pres (1996)

• Richard Miller, The Structure of Singing: System and Art in Vocal Technique. Wadsworth Publishing (2001)

• Richard Miller, National schools of singing: English, French, German, and Italian techniques of singing revisited. Scarecrow Press (2002)

• Garyth Nair, Voice – Tradition and Technology: A State-of-the-Art Studio. With CD. Singular (1999)

Intro: Sundberg’s demo

• Go to: The ugly voice poster

I. Digital audio files

• Audacity tutorial on digital audio

• Ripping CD tracks to .wav (Real, CDex)

• Saving .mp3 as .wav (Audacity,Cdex)

• Splitting and saving tracks from stereo (Audacity)

• (go to: CDEx, Audacity)

Our week 1 lab:A Sound Library of clips

• Making 1-channel .wav files < 30 sec

• Go to: Sound Library on web (logged in as a student)

II. Pitch• Frequencies of musical notes; each

doubling of frequency is an octave

• Semi-tone = almost 6%

• “in tune”: how close is close enough (20 cents?)

• “in tune”: steadiness

• Vibrato vs straight tone

Vibratos

• Dimensions of vibrato– Rate, range, amplitude vibrato

• Supposed good vibrato– 5.5 to 7 Hz, + .5 to 2 semitones

• What good a vibrato does, doesn’t do for the singer

• Examples of vibrato from classical, pop

Pitchtracking

• Hardest part: keeping track of F0 range

• Tuning forks and thin voices: don’t use cepstral method (sample file of tuning fork)

• Speech Analyzer: 500 Hz limit

• Problems tracking trills: changing step size and window length

Our week 2 lab: F0

• F0 matching

• F0 steadiness

• Measuring vibratos

III. Spectrum

• A bit on laryngeal anatomy and mechanism of vibration

• The voice source: F0 and overtones

• Line spectrum of source, FFT of output

• DVD “Human Speech”: speed of closing determines strength of higher harmonics

Partials, overtones?

• Partials = harmonics

• Overtones = partials above F0

Our week 3 lab: FFT

• FFT, LTAS in Pitchworks• FFT in Audacity: View-Plot spectrum (nice

for comparing window lengths)• pros and cons of Audacity/Pitchworks• Comparing spectra of different voice

qualities• Looking at strength of H1, number of

harmonics, amount of high-freq energy

IV. Recording the source

• Sundberg: All about the flow glottogram (Ug), from inverse filtering of Uo signal

2 key aspects of the flow glottogram

1. the maximum amplitude of the flow is directly proportional to the amplitude (in the source, not in the output) of the fundamental component

    and this affects the perceived “strength” of the voice, though not necessarily its overall loudness, which instead depends on the strongest partial

2. the maximum closing rate is proportional to the amplitudes of the overtones

Pressed, breathy, flow phonation • pressed phonation: high lung pressure combined with adducted glottis

– the adducted glottis requires more pressure to get vibration, but still, little air flows through the narrow and brief opening; low airflow = low amplitude of the flow glottogram, so a weak F0 component.

• breathy phonation: glottis is somewhat abducted so there is never complete closure – this means not only that some air flows through continuously, but also that the maximum flow is quite high; high airflow = a strong F0 component, but also a noise component in the voice (usually seen instead of higher-frequency partials)

• flow phonation: not so high lung pressure, and the most abducted glottis that will still give complete closure. This means the greatest possible amplitude of the F0 component without the noise. The amplitude of the F0 in flow phonation can be 15 dB or more greater than in pressed phonation.

A different view of the source: EGG

• Ch. 13 in Nair (1999) = “The Use of the Electroglottograph in the Voice Studio” by D. Miller and H. K. Schutte

• “one of the primary aims of training the classical singing voice will be to establish the habit of complete and abrupt closure, at least in mezzo forte and forte”

• Their sample sound file on next slide

Falsetto vs chest voice on [i]: little contact in falsetto

Our week 4 lab: EGG

• EGG: recording of each individual student, channels then split into separate .wav files

• Listen to EGG signal

• Spectrum of EGG signal

• Compare shape of pulses to examples

V. Resonances• A bit of source-filter theory and vowel

formants, including from DVD• “Singers formant”: extra energy around 3000

Hz (Sundberg says 2300-3000 Hz for basses, 3000-3800 for tenors), which allows a solo voice to stand out against an orchestra, or other singers

• (Sopranos don’t much need a singers formant against an orchestra, because any note above about B4 will stand out by itself. Similarly for amplified singers.)

Miller: singers formant

Singers formant

• Not really an additional formant, but a clustering of F3, F4, F5; when they are close together in frequency their strengths are mutually enhanced, giving one broad strong spectral peak.

• Male singers: enlarge the ventricle (just above the larynx), lower the larynx.

• It is not known how altos produce their singers formant.

• But I made a big difference in my voice by following male instructions

Speakers formant

• More like at 3500 Hz than 3000

• Property of speaking voices judged good

• Seen in some singing voices, especially in styles that are more like speaking

Our week 5 lab: resonances

• Looking at own voice and at recordings for singers formant; trying to increase singers formant

• Comparing vowels for the effect of different formant frequencies on strengths of different harmonics, esp., on strength of H1

VI. F1 tuning

• a strong voice matches H1 to F1, while a weak voice has no formant near H1

• Good illustration of this on DVD: the good voice and the bad voice samples

• Sundberg says that tuning H1 to F1 can add up to 30dB to the sound level.

• F1 is raised by opening the mouth more, or shortening the vocal tract (e.g. smiling)

When F0 is above F1

• F0 > F1 for many soprano notes• F1 cannot match F0, and also vowel

qualities are indistinct• trained singers tend to adjust the vowel

quality so that the F1 moves up, in the direction of F0.

• (Is this what I do? No, I generally have F1 tuned to H2 - see later slide.)

Sundberg: F1 tuning when F0>F1

The soprano challenge

• Recently a study of this effect, explicitly testing what Sundberg had said, got a lot of publicity:

http://www.phys.unsw.edu.au/~jw/soprane.html (this page saved to computer but without sound)

• They found that a trained soprano singing above about 440 Hz tuned every vowel’s F1 to the F0.

Miller on passagio & tuning “The crucial point in a correct execution of passaggio is to avoid pushing

the chest register beyond its natural limits by means of a forced, “shouty” production. This tendency, natural in most untrained voices, appears as a compulsion to tune the first formant to the second harmonic of the voice source in the attempt to extend the chest register upward. Singing teachers recognize this phenomenon in the undesirable raising of the larynx when approaching the upper range.” [this increases the frequency of F1] “The larynx raising is thus a maneuver of last resort to get the first formant higher in order to add a semitone or two to the chest register. (...) The typical high note which is “forced” in this way has a second harmonic with a level 15 to 25 dB higher than the first harmonic. (...) One reason for the strong tendency to tune F1 to H2 on high notes in the chest register is that the resulting resonance is quite powerful. (...) A compensatory adjustment for this loss that most accomplished (opera) singers employ is the tuning of F2 to a higher harmonic.”

Our week 6 lab: F1 tuning

• Mapping out a singer’s pitch range and F1 range; which vowels have F1 in the overall F0 range, and which vowels would be best to sing on a given pitch to get F1 near that F0 (e.g. if I can sing from A220 to A880)

• Trying to tune F1 to F0

• Passaggio out of chest voice

VII. Breathing in singing

Recall:

• Muscles that can participate in inhalation (expansion): external intercostals, diaphragm

• Muscles that can participate in exhalation (contraction): internal intercostals, abs

Breathing in singing

• Normal breathing: about .5 liters 12 times/minute, with active inspiration and passive expiration.

• Singing: much longer breaths, and more total air in a breath. More of the air in the lungs is exhaled by professional singers.

Subglottal pressure

• Pressures generated in speech are much lower than those in singing, but even singing pressures are less than those used by reed and brass instrument players, which in turn are less than those used in lifting heavy weights (with the glottis completely closed).

• In singing, pressure is higher for louder phonation and for higher pitches: A doubling of subglottal pressure gives about a doubling in loudness, and subglottal pressure also about doubles when F0 doubles.

Oral flow

• The flow of air out of the mouth depends on the pressure in the lungs, and the size of the opening through the larynx and vocal tract.

• In pressed phonation, subglottal pressure is high, but the glottis is nearly closed so airflow is low. In breathy phonation, the more-open glottis lets air leak out throughout the glottal cycle.

• Airflow tends to increase for louder or higher-pitched notes.

• Vibrato uses more air than straight tones.

Trained vs. untrained

• Classically trained singers have lower subglottal pressures than do untrained singers, and these pressures are lower in speech as well as singing.

• Trained singers have lower airflow rates in singing than do untrained singers, but the same airflow rates in speech.

• Trained singers thus have more efficient phonation: they use less air to get strong vocal fold vibrations.

Loudness control with

a. phonation: the right amount of vocal fold adduction (Sundberg’s flow phonation)

b. the vocal tract: formant tuning, singers formant

c. lung pressure: higher pressure and higher airflow through the glottis. The power of the glottal source increases by 6 dB for every doubling of the lung pressure

Sundberg: Ps vs. pitch

sound level (S), subglottal pressure (P) and oral airflow (A) from a professional singer’s ascending scale, showing how pressure increases a lot as pitch increases, even when airflow is fairly constant and sound level increases only somewhat

Sundberg: Ps vs. pitch

the clear relation of loudness, pressure and pitch in these quicker triads

Our week 7 lab: aero

• Pressure and flow for each student

• Did they show the relation of Ps, Uo, and F0 (with relatively fixed loudness) as in the Sundberg example figure?

VIII. Consonants

• 2 chapters each in Miller, Nair• Nair says that trained singers have greater amplitude,

more energy in more harmonics, and stronger resonances in their consonants, and that this helps smooth connections between consonants and vowels.

• Nair’s “resonance checklist” for consonants: jaw down, “proper tongue configuration”, raised velum, pharynx open and relaxed, larynx relaxed and low in the throat. No extreme lip spreading or rounding, because both tend to raise the jaw.

Consonants

• F0 perturbation effects from consonants• Miller is mostly concerned with agility in

consonant articulation so that consonants can be made quickly and take up little time relative to vowels, and he includes agility exercises

• Nair mentions lengthening of glides for dramatic effect, advises minimal noise for word-final consonants

Our week 8 lab: consonants

• Comparing sung consonants for relative vowel-likeness, speed

• Pitch perturbations

• Dramatic effect of lengthening, releasing, etc. of consonants

IX. Comparing singing styles

• Miller’s book on western classical traditions• Several comparisons of genres in the

literature indicate that on various measures, pop, Country-Western and Broadway singing are more like speaking than is classical (operatic) singing

• Vocal tract in classical singing has wider lower pharynx, wider oral cavity

Our week 9 lab: final projects

• Most students are comparing song samples, either commerical or recorded by them

• Projects are being constructed as webpages– Easy to combine presentation of text, graphics,

sound materials– When done, can be viewed by whole class

• Class on using Dreamweaver by ITC

X. Titze on warm-ups

• Titze explains warm-up exercises in terms of bringing all systems up gradually

• Acoustic loading for respiratory warm-up– increase the acoustic loading on the vocal folds

with humming, trills, singing into a straw - lets the vocal folds vibrate with more abduction, and with overall lower Ps for an easy start

– increase F0 so that Ps must increase