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The Impact of Vocal Warm-Up Exercises on the
Objective Vocal Quality in Female Students Training
to be Speech Language Pathologists
*Kristiane M. Van Lierde, *Evelien D’haeseleer, *Nele Baudonck, *Sofie Claeys, †Mark De Bodt,
and ‡Mara Behlau, *Ghent, yAntwerp, Belgium, and zSa
˜o Paulo, Brazil
Summary: Purpose. The purpose of this study was to determine the impact of a specific vocal warm-up (WU) pro-
gram—focused on the improvement of the dynamics of the extrinsic and intrinsic laryngeal muscles—on the objective
vocal quality in Dutch female students who are getting trained to be speech language pathologists (SLPs). Hypotheti-
cally, one can assume that the objective vocal quality will increase after vocal WU exercises in SLPs in comparison with
the matched control group that receives no WU program.
Methods. This was a pretest-posttest control group design study, in which 45 female future SLPs were randomly as-
signed into two groups. The experimental group received a well-defined vocal WU program, whereas the control group
took 30 minutes of vocal rest. Objective assessment techniques (aerodynamic, vocal range, acoustic measurements, and
Dysphonia Severity Index [DSI]) were used.
Results. After vocal WU, a significant increased DSI value, increased vocal performance (with lower intensity and
higher frequency), and increased fundamental frequency (F
0
) were measured.
Conclusions. Clinically, there is clear evidence that warming up the vocal mechanism is beneficial to the objective
vocal quality and the vocal performance in future SLPs. To what extent the repetition of these vocal WU exercises has
the possibility to maintain increased objective vocal quality in these future professional voice users is subject to further
research.
Key Words: Vocal warm-up–Objective vocal quality–Vocal muscle approach–Dysphonia Severity Index–Speech
language pathologists.
INTRODUCTION
It has widely been accepted that athletes should perform warm-
up (WU) activities immediately before a physically demanding
activity.
1–4
WU is intended to improve muscle dynamics and to
prepare the athlete for the demands of exercises. Focused on vo-
cal characteristics, several authors
5–9
stated that vocal WU pre-
pares body and mind for more strenuous or specific vocal
activity, prevents vocal injury, and provides optimum prepara-
tion for performance. According to Heurer et al,
10
the WU is im-
portant in voice training and prepares the vocal folds and
muscles for the demands of the day. AWU and cool-down rou-
tine includes muscular strength of motion exercises (useful for
relaxation and to heighten the patient’s tactile feedback system)
and phonation and speaking exercises. Vocal WU exercises are
expected to increase blood flow to the vocal folds and decrease
muscle viscosity and perhaps nonmuscular tissue viscosity.
11
Most studies that have examined the effect of vocal WU focused
on phonation threshold pressure (PTP) as shown in Table 1.
According to Baken and Orlikoff,
17
the PTP is described as
the minimal driving pressure for vocal fold oscillation. Ade-
quate speech requires a subglottic pressure of no less than
5cmH
2
O for at least 5 seconds. Studies evaluating the effect
of vocal WU on PTP show conflicting results. Although Vintturi
et al
13
and Motel et al
14
reported a significant rise of PTP, other
authors
7,11,16
found no effect. According to Milbrath and Solo-
mon,
11
PTP is not a sensitive or specific measure to study
changes in vocal function after vocal WU, because the results
failed to support any significant changes in PTP after each of
the vocal tasks. McHenry et al
16
used the acoustic parameter jit-
ter also to examine the impact of vocal WU. To what extent the
significant lower jitter values in males are reflected in a better
vocal function is not further discussed. We support the sugges-
tion of Milbrath and Solomon
11
that a more sensitive measure is
necessary to assess the impact of vocal WU exercises on vocal
function. Also, the comparison between the aforementioned
studies is somewhat difficult, because rather small experimental
subject groups (between four and 20 subjects)
7,11,12,14–16
with
heterogeneous vocal conditions (amateur, professional, or rec-
reational singers with or without vocal therapy training and
nonsingers with or without vocal complaints),
7,11–16
different
vocal exposure arrangements (varying between 10 and 45 min-
utes of vocal WU exercises),
7,11–16
different assessment
methods (self-evaluation, pressure transducer, acoustic mea-
sures), and speech samples (syllable, syllable string, counting,
sustained vowel)
7,11–16
were used. Moreover, none of these
studies
7,12–16
incorporated a control group. Only in the study
of Vintturi et al
13
a large subject group (40 female and 40
male young students) was used. In the study of Milbrath and
Solomon,
11
vocal rest was used as a placebo condition.
The purpose of this study was to determine the impact of
a specific vocal WU program—focused on the improvement
of the dynamics of the extrinsic and intrinsic laryngeal
Accepted for publication November 5, 2009.
From the *Department of ENT and Head and Neck Surgery, Ghent University Hospital,
Ghent, Belgium; yDepartment of ENT and Head and Neck Surgery, Antwerp University
Hospital, Antwerp, Belgium; and the zGraduate Program in Human Communication Dis-
orders, Center of Voice Studies, Federal University of Sa
˜o Paulo (UNIFESP-EPM), Sa
˜o
Paulo, Brazil.
Address correspondence and reprint requests to Kristiane M. Van Lierde, Department of
ENT and Head and Neck Surgery, University Hospital, 2P1, Dienst logopedie, De Pintelaan
185, 9000 Ghent, Belgium. E-mail: kristiane.vanlierde@ugent.be
Journal of Voice, Vol. 25, No. 3, pp. e115-e121
0892-1997/$36.00
Ó2011 The Voice Foundation
doi:10.1016/j.jvoice.2009.11.004
TABLE 1.
Summary of Recent Studies on the Impact of Vocal WU Exercises
Authors
Subjects (Number,
Gender, Age Range) Vocal WU Procedure Methods Speech Sample Results
Elliot et al
7
n¼10
7 females (22–44)
3 males (32–57)
Amateur singers
with voice training
Descending melodic
pattern on /mu:/ + pitch
changes+ different vowels +
different degrees of vocal loudness
Time: 30 min
Self-evaluation
Pressure transducer
Singing different
pitches in ascending
order 63/pa/ as soft
as possible on each
pitch
Better subjective
voice timbre
Easier to sing
at high pitches
No significant
difference in PTP
Great variability
on the PTP
Blaylock
12
n¼4 with
voice disorders
1 professional
singer (38)
2 recreational
singers (36,47)
1 nonsinger (46)
Followed medical
and speech
therapy
Sequence of vocal
exercises covering the spectrum
of the vocal range (tempo, vowels,
range, volume,
intensity)
Time: 15 min once a day
Weekly sessions with voice teacher
Perceptual evaluation of
the overall voice
quality (6 voice
teachers)
Comparative voice
analysis (wave-
forms, sonograms,
spectrograms)
Counting 1 to 5 (speak
and sing)
Free conversation
Sustained /ah/ /oh/
Rainbow passage
Improvement in
subjective
and objective vocal
quality over time
Vintturi et al
13
n¼80 (22 y /
18–45)
40 female young
students
40 male young
students
No voice therapy
or formal voice
training
Reading aloud a novel for 45 min Glottal flow
Intraoral pressure
Voice range profile
Three strings of five
/pa:pa/ normally,
softly, and loudly
(shouting)
Significant rise
in the intraoral
pressure of
males in soft
phonation
Change toward
hyperfunctional/
pressed voice
production
Motel et al
14
n¼10 (20.4y/1921)
Female soprano
singers with
normal voices
Sang regularly
in private
lessons, a choir
or musical group
Phonation threshold task:
Gliding to the highest phonatory
pitch + gliding downward to
the lowest pitch
Time: 10 min
Volume velocity
using a wide
bandwith differential
pressure transducer
/p/ syllable string of
seven syllables on
a single breath at
comfortable, low,
and high pitch levels
Significant increase
of PTP for
high-pitch
phonation
Milbrath and
Solomon
11
n¼8 (22.5 y /
20–28 y)
Females
complaining
of vocal fatigue
without laryngeal
pathology
Respiration (stretching and breath-
ing) + resonance (humming at
different pitches and singing /
ma:/) + phonation (sustained vowel
/i/, ascending and descending pitch
glide, sustaining several notes)
Time: 15–20 min
Pressure transducer PTP and PPE at three
pitches 73/pi/ at a
rate of 1.5 syllables/s
Results failed
to reveal
statistically
significant changes
in PTP or PPE
High between-subject
variability
Increase in PTP after
Journal of Voice, Vol. 25, No. 3, 2011e116
muscles—on the objective vocal quality using a multiparameter
approach (Dysphonia Severity Index [DSI]) in Dutch female
students getting trained to be speech language pathologists
(SLPs). Hypothetically, one can assume that the objective vocal
quality will increase after vocal WU exercises in future profes-
sional voice users in comparison with the matched control
group that received no WU program.
METHODS
Subjects
One hundred nineteen female students in speech and language
pathology at the Ghent University were invited in written to par-
ticipate in this study. Ninety students with a mean age of 18.7
years (range: 18.2–21.3 years) agreed to participate. Forty-
five female subjects were randomly selected and included in
the experimental subject group, and 45 female subjects were in-
cluded in the control group. The mean ages of the experimental
and the control group were not significantly different (Mann-
Whitney Utest, P< 0.001).
None of the participants had a history of hearing defects and
neurological, velopharyngeal, and laryngological problems. All
the subjects were in good physical and mental state of
well-being, were nonsmokers, were aware of the vocal hygiene
behavior, and followed no voice therapy of training. None of
them was a professional voice user. Each subject was assessed
by an otorhinolaryngologist performing a complete ear, nose,
and throat examination to exclude voice disorders and nasal
and ear diseases. For the nasopharyngeal and laryngeal exami-
nation, direct flexible laryngoscopy was used. A Thudichum
speculum (Intraspac) was used for inspection of the nose. Mi-
croscopic tympanoscopy was performed in every patient, and
hearing was assessed for both ears separately at standard audio-
metric frequencies. Forty-five female subjects were randomly
selected and included in the experimental subject group, and
45 female subjects were included in the control group. This
study was approved by the human subjects committee of the
University of Ghent.
Vocal assessment techniques
To determine the objective vocal quality, objective assessment
techniques (aerodynamic, vocal range, acoustic measurements,
and DSI
18
) were used. The DSI, which is designed to establish
an objective and quantitative correlate of perceived vocal qual-
ity, is used. The DSI is based on the weighted combination of
four voice measurements: maximum phonation time (MPT),
highest frequency (F-high), lowest intensity (I-low), and jitter.
These measurements were accomplished by means of the Com-
puterized Speech Lab (CSL; Kay Elemetrics Corp., Lincoln
Park, NJ and model 4300, Sony microphone ECM-7171;
Sony, Japan). The mouth to microphone distance was set
at 30 cm.
MPT was measured on the basis of two test trials with the
vowel /a/ sustained at the participant’s habitual pitch and loud-
ness in free field (without any mouthpiece) and in sitting posi-
tion. The MPT was also modeled by the experimenters (E.D.,
N.B.), and the participant was visually encouraged to produce
Placebo condition of vocal rest
(30 min)
the loud-reading
task at the highest
pitch
Amir et al
15
n¼20 (18.6 y)
Female singers
with professional
classical voice
training
Each singer used a different WU
routine with body posture
alignment, relaxation, breathing,
and vocal exercises at different
pitches, registers, and amplitude
levels
Time: 11 min
Multi Dimensional
Voice Program
(Kay Elemetrics Corp.)
Sustained vowels /a/
/i/ in three different
pitches
Decreased jitter,
relative average
perturbation, pitch
perturbation
quotient, shimmer
and amplitude
perturbation
quotient, and NHR
McHenry et al
16
n¼20 (17–25 y)
10 males
10 females
Familiar with
vocal WU
Normal voices
Condition 1: vocal WU
Silent progressive relaxation in
supine position + soft phonation
while lying down and standing
up + increasing pitch and loudness
in standing position
Time: 20 min
Condition 2: vocal WU + aerobic
(combined WU)
Pressure transducer
Aerodynamic system
Acoustic measures (Kay
Elemetrics Corp.)
Self-rating of vocal effort
73/pi/ at a rate of 1.5
syllables/s
Sustained vowel
No significant
differences in PTP
for males
Significant reduction of
PTP for females in
condition 2
Significant lower
jitter in males
in condition 1
Abbreviation: PPE, self-perceived phonatory effort.
Kristiane M. Van Lierde, et al Speech-Language Pathologists e117
the longest possible sample. The best trial was retained for fur-
ther analysis. The F-high and the I-low were measured with the
voice range profile from the CSL following the procedure out-
lined by Heylen et al
19
(ie, a ‘‘rough’’ contour was generated
by having the subject vocalize at his or her lowest and highest
frequencies using the softest and greatest intensities at each fre-
quency extreme).
Jitter, along with fundamental frequency (F
0
), shimmer, and
noise to harmonic ratio (NHR), was obtained by the Multi Di-
mensional Voice Program from CSL. A mid-vowel segment
on a sustained /a/, at habitual loudness and pitch, was used.
The DSI is constructed as (0.13 3MPT) + (0.0053 3F-high) –
(0.26 3I-low) – (1.18 3jitter (%) + 12.4. DSI ¼+5 for perceptu-
ally normal voices, and DSI ¼5 for severely dysphonic voi-
ces. The more negative a person’s index, the worse is his or
her vocal quality.
18
To calculate it as a percentage, the DSI
value is increased by 5 points and then multiplied by 10. Hun-
dred percent is optimal, and 0% indicates a bad voice.
Experimental design
The objective measurement protocol was immediately done be-
fore and after vocal WU exercises (experimental group) or be-
fore and after vocal rest (control group) by two research
assistants (E.D. and N.B.) blinded to the purpose and the stages
of the study. Individual data of the vocal characteristics were
collected in the morning in a sound-treated room for both the
experimental and control groups. Participants were asked to
perform the vocal WU exercises as modeled by the voice ther-
apist (K.M.V.L.) for approximately 30 minutes. In the control
group, no vocal WU exercises were performed. The subjects
were instructed to have vocal rest for 30 minutes while reading
a journal. None of the participants had difficulties in performing
the exercises, and modeling was used to control a good execu-
tion. The voice therapist guided the subjects through the exer-
cises with verbal information or corrective feedback after
every production. Positive reinforcement was given after every
correct production.
Vocal warm-up program
The main purpose of the vocal WU program was to improve the
dynamics of the extrinsic and intrinsic laryngeal muscles. Exer-
cises were selected both to improve muscle flexibility and also
to enhance voice production awareness. The proposed program
was designed starting with large muscle exercises and ending
with selected sound production control. The first exercise in-
volves the cervical muscle region followed by stretching of
the muscles of the mouth and pharynx in combination with
free vowel production. Then, vocal fold shortening (vocal fry)
followed by stretching (hyper high blowing) is the training fo-
cus. After vocal fold flexibility, mucosal wave is enhanced
through voiced tongue trills. Resonance exercises are intro-
duced to improve source-filter interaction, and controlled fre-
quency variability is trained with ascending and descending
tones. Specific vowels are targeted. The WU program ends
with the hand-over-mouth technique to control the reduced
supraglottic constriction.
Stretching exercises. All the participants were questioned
about any restriction to perform cervical movements. Breathing
freely was monitored during the stretching performance.
1. Active stretching of the left and right sternocleidomastoid
muscles (action: tilts head back or rotates skull)
2. Active stretching of trapezius muscle (action: stabilizes
the shoulder)
3. Active stretching of the mylohyoid muscle (action: supra-
hyoid muscle that elevates floor of the mouth affecting
tongue height)
Vocal exercises.
1. Open mouth approach combined with gliding yawning on
the sounds /a/ /e/ /u/ /ie/ /ij/. There is a hypothesized al-
ternate predominance of the musculus cricothyroid
(CT) and musculus thyroarytenoid (TA) action. This ap-
proach promotes more natural size-mass adjustments and
more optimum approximation of the vocal folds. A gentle
stretching and shortening of the vocal folds is hypothe-
sized as well as widening of the supraglottis and pharynx
and elevation of the velum, which favors oral resonance.
With this combination, the subjects used their vocal
mechanism with less effort and strain.
20,21
2. Glottal fry (pulse register) on the sounds /a//e//u//ie/3i//:
There is a hypothesized action of the musculus. TA
(shortening of vocal folds) and musculus. arytenoids
(closure of posterior third of the glottis). An accurate
airflow control is required to keep the pulse sound with-
out extra tension. The vocal fold adduction during the
pulse register hypothesizes a greater increase in sub-
glottic air pressure.
22
3. Hyper high-blowing exercise: There is a hypothesized re-
duction of vocal tract constriction, action of the muscu-
lus. CT and less action of the musculus. TA, resulting
in a great elongation of vocal folds. Hyper high blowing
is a technique where the individual is instructed to blow
audible air with pursed lips during the production of
a high-pitched sound. The quality of the sound is less im-
portant than the muscular adjustment (elongated vocal
folds with reduced adductory collision forces). There is
a hypothesized slight approximation of the vocal folds,
with an open supraglottic area. The hypothesized open
supraglottic area is caused by the small airflow outlet
area of the lips, creating a backward impedance. This ex-
ercise can be seen as a semi-occluded vocal tract tech-
nique with a predominance of musculus. CT action.
4. Voiced tongue trills: There is a hypothesized action of the
phonatory muscles with intense passive vibration of the
cartilaginous skeleton of the larynx and its whole content.
A complete glottal closure and soft mucosal wave vibra-
tion because of the small airflow outlet through the semi-
occluded lips is hypothesized. According to Titze,
23
the
reverse sound alters the glottal flow and acts over the mu-
cosal wave, reducing vocal fold collision.
5. Resonance exercises: There is a hypothesized vocal fold
closure together with the lowering of the velum
Journal of Voice, Vol. 25, No. 3, 2011e118
increasing the length of the vocal tract. Resonance exer-
cises contribute to a better source-filter interaction and
are widely used in voice rehabilitation. These exercises
help to achieve an easier (and less traumatic to the laryn-
geal tissues) voice production.
24
Moreover, the front fo-
cus tone helps to create a vibratory schema to reduce
laryngeal resonance.
25
6. Ascending and descending tones: There is a hypothesized
differential contraction of TA muscle, CT muscle, with
contributions from the posterior cricoarytenoid and the
extrinsic laryngeal muscle groups.
7. Hand-over-mouth technique: This exercise uses the clo-
sure of the mouth while producing a stable sound to
free constrictions along the vocal tract. The subject is en-
couraged to monitor the vibrations in the open vocal tract
around the lips and in the hand covering the mouth. The
goal is to maintain the nonconstricted vocal tract during
phonation (perceiving a clearer and more easily produced
voice
26
) when the hand is not covering the mouth. Titze
27
addressed the acoustic features of a group of maneuvers
that share a feature he identified as a ‘‘semi-occluded vo-
cal tract.’’ This exercise can be included in that principle.
The entire individual program of vocal WU exercises
(stretching and vocal exercises) took approximately 30 minutes.
Statistical analysis
The statistical program SPSS (version 16) was used for the sta-
tistical analysis of the voice data. SPSS is among the most widely
used programs for statistical analysis in social science. To inves-
tigate whether the distribution of the parameters are significantly
different from a normal distribution, the Kolmogorov-Smirnov
test was used. A significant value (a< 0.01) indicates a deviation
from normality. In case of a normal distribution [for the vocal
parameters: MPT, I-low, highest intensity (I-high), F-high,
shimmer, and DSI], a paired sample ttest (two tailed) was
performed for the comparison of the precondition (before vocal
WU or voice rest) and postcondition (after vocal WU or voice
rest). For the comparison of the nonnormal distributed data
[lowest frequency (F-low) F
0
, and jitter], the Wilcoxon
signed-rank test for two related samples was used. The signifi-
cance level was set at P¼0.05 in all tests. In case of a statistical
significant difference (P< 0.05), the effect size (r) was reported.
The effect size is a measure of the strength of the relationship be-
tween two variables. Effect sizes are useful, because they pro-
vide an objective measure of the importance of an effect.
Effect sizes larger than 0.10, 0.30, and 0.05 are accepted as
a small, medium, and large effects, respectively.
RESULTS
The results of the voice assessment before and after vocal WU
exercises and vocal rest are provided in Table 2.Figure 1 repre-
sents the changes of DSI before and after vocal WU exercises
(experimental group) and vocal rest (control group). The paired
sample ttest revealed a significant effect of vocal WU exercises
for the objective overall vocal quality, represented by the DSI
TABLE 2.
The Results of the Objective Assessment Techniques Before and After Vocal WU Exercises (Condition 1) and Vocal Rest (Condition 2)
Condition 1,
Prevocal WU
Condition 1,
Postvocal WU Impact of Vocal WU Condition 2,
Prevocal Rest
Condition 2,
Postvocal Rest Impact of Vocal Rest
Parameters Mean (SD) Mean (SD) PValue rValue if P< 0.05 Mean (SD) Mean (SD) PValue
Aerodynamic
MPT (s) 17.5 (4.4) 18.3 (7.2) 0.232 17.5 (5.6) 16.9 (5.4) 0.417
Voice range profile
I-low (dB) 57.9 (4.0) 55.3 (3.8) 0.000*0.681 56.1 (3.4) 56.7 (3) 0.238
I-high (dB) 127.1 (5.1) 105.8 (5.7) 0.351 159.9 (372) 104.5 (4.8) 0.323
F-high (Hz) 892.5 (193) 1020.7 (187) 0.000*0.688 895.6 (198) 922.6 (214.4) 0.121
F-low (Hz) 152.7 (19) 151.9 (17.3) 0.499 147.8 (20.9) 148.1 (18.6) 0.384
Acoustic
F
0
(Hz) 214.4 (14.7) 219.1 (16) 0.002*0.800 207.8 (12.5) 207.7 (13.4) 0.925
Jitter (%) 1.1 (0.6) 1.2 (0.7) 0.561 1.2 (0.6) 1.2 (0.7) 0.481
Shimmer (%) 2.6 (0.6) 2.5 (0.7) 0.669 2.7 (0.7) 2.7 (0.7) 0.573
NHR 0.11 (0.03) 0.11 (0.03) 0.928 0.13 (0.09) 0.13 (0.11) 0.946
DSI (%) 3.21 (2.14) 4.7 (2.2) 0.000*0.713 3.5 (1.9) 3.4 (1.7) 0.599
Abbreviation: SD, standard deviation.
Impact of vocal WU ¼level of significance (P) with effect size (r) between the results of the objective assessment techniques pre- and postvocal WU exercises (condition 1). Impact of vocal rest ¼level of
significance (P) with effect size (r) between the results of the objective assessment techniques pre- and postvocal rests (condition 2).
* Significance level < 0.05.
Kristiane M. Van Lierde, et al Speech-Language Pathologists e119
outcome measure (and the components I-low and F-high). No
significant differences were measured between the objective
vocal quality for the DSI values (and the components of the
DSI) before and after vocal rest. The Wilcoxon signed-rank
test for two related samples revealed a significant effect of vocal
WU for the acoustic parameter F
0
.
DISCUSSION
The purpose of the present study was to measure the impact of
a specific program of vocal WU exercises in 40 female students
training to be SLPs. To the best of our knowledge, pretest-post-
test control group designs that document the objective improve-
ment (based on a multiparameter approach) of vocal quality
after vocal WU appear to be very limited. As hypothesized,
the results of this study showed significant improvement of
the objective vocal quality after a vocal WU of approximately
30 minutes. No improvement was measured in the control
group in which 30 minutes of vocal rest is respected. As the
DSI is a weighted variable, small improvements (closer to +5
or 100%) are very indicative for vocal quality improvement,
18
and it is found to be a very sensitive tool for quantifying the
effect of various vocal therapy techniques.
28
The DSI value
of the subject improved from +3.2, corresponding to a DSI%
of 82%, to +4.7 or 97%. Analysis of the components of the
DSI show that the main variables responsible for this difference
after a vocal WU program are lowest intensity and highest fre-
quency. After vocal WU, the voices of the female students have
an overall increased objective vocal quality, increased vocal
performance (with lower intensity and higher frequency
capacities), and increased F
0
(219 Hz, but situated within the
normal range 167–258).
17
Also, in the study of Blaylock,
12
an
improvement of the objective vocal characteristics—based on
a comparative voice analysis of waveforms, sonograms, and
spectrograms—was measured. The significant lower jitter
value
12,15
and NHR
15
are not found in this study. It is not clear
how these differences could be explained. Hypothetically, one
can assume that the difference in results can be explained by
the use of different assessment methods (waveforms, sono-
grams, spectograms
12
vs acoustic analysis), different duration
and content of the vocal WU exercises (sequence of vocal exer-
cises covering the spectrum of the vocal range for 15 minutes
once a day
12
vs use of an individually trained WU routine of
body posture, relaxation, breathing, and vocal exercises for
11 minutes
15
vs stretching and vocal exercises for 30 minutes),
and especially a difference in number and vocal background of
the participants (20 female singers with professional clinical
voice training
15
vs one professional, one recreational, and one
nonsinger with voice disorders
12
vs 40 future professional voice
users without vocal training and voice disorders).
Clinically, there is clear evidence that warming up the vocal
mechanism is beneficial to the objective vocal quality and the
vocal performance in future professional voice users training
to be SLPs. In a previous study,
29
it was found that student
SLPs have a borderline vocal quality corresponding to
a DSI% of 68%. The vocal demand of SLPs requires special
skills (voice coaching, practical use of several voice therapy
techniques) that go beyond the conversational level. Moreover,
the results of the study of Gottliebson et al
30
suggest that voice
problems among future SLPs (12%) are more common than the
3–9% reported in the general population and similar to the 11%
previously reported for teachers. To what extent the repetition
of these vocal WU exercises has the possibility to maintain
the increased objective vocal quality in these future profes-
sional voice users is subject to further research.
Limitations of this study are that assessments of outcome after
vocal WU are limited to objective measures using a multiparam-
eter approach. A self-rating would have been valuable informa-
tion to obtain together with a control on what voicing was
done by subjects before the collection of the data. Furthermore,
a follow-up assessment to measure the maintenance of the in-
creased vocal quality and performances after vocal WU could
give valuable information but was not possible because of prac-
tical reasons. To what extent a different content (conversational
speech or reading) and duration of vocal WU program result in
a change in objectivevocal quality is subject to further research.
In conclusion, the results of this study show evidence that
a vocal WU program is an effective technique to increase the
overall vocal quality. Moreover, there is significant evidence
that vocal WU is beneficial to vocal performances in female fu-
ture professional voice users (without vocal pathology). The
precise way in which vocal WU has an effect on vocal quality
has not been addressed in this experiment but merits study.
The authors also suggest that further research into this topic
could focus on subjects with vocal pathology.
REFERENCES
1. Woods K, Bishop P, Jones E. Warm-up and stretching in the prevention of
muscular injury. Sports Med. 2007;37:1089–1099.
2. Weerapong P, Hume PA, Kolt GS. Stretching: mechanism and benefits for
sport performance and injury prevention. Phys Ther Rev. 2004;95:189–206.
3. Verrall GM, Slavontinek JP, Barnes PG. The effects of sport specific train-
ing on reducing the incidence of hamstring injuries in professional Austra-
lian rules football players. Br J Sports Med. 2005;39:363–368.
4. Curry BS, Chengkalath D, Crouch G, Romance M, Manns P. Acute effects
of dynamic stretching, static stretching and light aerobic activity on muscu-
lar performance in women. J Strength Cond Res. 2009;23:1811–1819.
5. Sundberg J. The Science of the Singing Voice. DeKalb, IL: Northern Illinois
University Press; 1987. pp. 192–194.
6. Sataloff RT. Introduction to Treating Voice Abuse. In: Sataloff RT, ed. Pro-
fessional Voice: The Science and Art of Clinical Care. New York, NY: Ra-
ven Press; 1991:311–312.
FIGURE 1. The changes of DSI before and after vocal WU exercises
(subjects) and vocal rest (controls).
Journal of Voice, Vol. 25, No. 3, 2011e120
7. Elliot N, Sundberg J, Gramming P. What happens during vocal warm-up?
J Voice. 1995;9:37–44.
8. Welham N, Maclagan M. Vocal fatigue in young trained singers across
a solo performance [abstract]. ASHA Proc. 2000;5:157.
9. Saxon KG, Berry SL. Vocal exercise physiology: same principles, new
training paradigms. J Sing. 2009;66:51–57.
10. Heuer RJ, Rulnick RK, Horman M, Perez KS, Emerich KA, Sataloff RT.
Voice therapy. In: Sataloff RT, ed. Vocal Health and Pedagogy. Advanced
Assessment and Treatment. 2nd ed. San Diego, CA: Plural Publishing
Inc; 2006:227–251.
11. Milbrath RL, Solomon NP. Do vocal warm-up exercises alleviate vocal fa-
tigue? J Speech Lang Hear Res. 2003;46:422–436.
12. Blaylock TR. Effects of systematized vocal warm-up on voices with disor-
ders of various etiologies. J Voice. 1999;13:43–50.
13. Vintturi J, Alku P, Lauri ER, Sala E, Sihvo M, Vilkman E. Objective anal-
ysis of vocal warm-up with special reference to ergonomic factors. J Voice.
2001;15:36–53.
14. Motel T, Fisher K, Leydon C. Vocal warm-upincreases phonation threshold
pressure in soprano singers at high pitch. J Voice. 2003;17:160–167.
15. Amir O, Amir N, Michaeli O. Evaluating the influence of warmup on sing-
ing voice quality using acoustic measures. J Voice. 2005;19:252–260.
16. McHenry M, Johnson J, Foshea B. The effect of specific versus combined
warm-up strategies on the voice. JVoice. 2009;23:572–576.
17. Baken RJ, Orlikoff RF. Clinical Measurement of Speech and Voice. San
Diego, CA: Singular/Thomson Learning; 2000.
18. Wuyts F, De Bodt M, Molenberghs G, et al. The Dysphonia Severity Index:
an objective measure of vocal quality based on a multiparameter approach.
J Speech Lang Hear Res. 2000;43:796–809.
19. Heylen L, Wuyts F, Mertens F, De Bodt M, Pattyn J, Croux C, Van de
Heyning PH. Evaluation of the vocal performance of children usinga voice
range profile index. J Speech Lang Hear Res. 1998;41:232–238.
20. Boone D, McFarlane S. The Voice and Voice Therapy. New York, NY: Pren-
tice Hall; 1994.
21. Benninger MS, Murry T. The Performer’s Voice. San Diego, CA: Plural
Publishing; 2006.
22. Stemple JC, Glaze LE, Klaben BG. Clinical Voice Pathology, Theory and
Management. San Diego, CA: Plural Publishing; 2000.
23. Titze I. How are harmonics produced at the voice source? J Sing. 2009;65:
575–576.
24. Roy N, Weinrich B, Gray S, Stemple J, Sapienza C. Three treatments for
teachers with voice disorders: a randomized clinical trial. J Speech Lang
Hear Res. 2003;46:670–688.
25. Barrichelo-Lindstro
¨m V, Behlau M. Resonant voice in acting students: per-
ceptual and acoustic correlates of the trained Y-Buzz by Lessac. J Voice.
2009;23:603–609.
26. Behlau M, Oliveira G. Hand-over-mouth. In: Behrman A, Haskell J, eds.
Exercises for Voice Therapy. San Diego, CA: Plural Publishing; 2008:35–
37.
27. Titze IR. Voice training and therapy with semi-occluded vocal tract: ratio-
nal and scientific underpinnings. J Speech Lang Hear Res. 2006;49:
448–459.
28. Van Lierde K, Deley S, Bernart L, De Bodt M, Van Cauwenberge P.
Outcome of manual voice therapy in four Dutch adults with persistent
moderate to severe vocal hyperfunction: a pilot study. J Voice. 2004;18:
467–474.
29. Van Lierde K, D’Haeseleer E, Wuyts F, de Ley S, Geldof R, De Vuyst J,
Claeys S. The objective vocal quality, vocal risk factors, vocal complaints,
and corporal pain in Dutch female students training to be speech-language
pathologists during the 4 years of study. Accepted for publication in J Voice,
2009.
30. Gottliebson RO, Lee L, Weinrich B, Sanders J. Voice problems of future
speech-language pathologists. J Voice. 2007;21:699–704.
Kristiane M. Van Lierde, et al Speech-Language Pathologists e121
