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Voice Therapy Outcome—A Randomized Clinical Trial
Comparing Individual Voice Therapy, Therapy in Group, and
Controls Without Therapy
*Ann-Christine Ohlsson, †Hans Dotevall, ‡Inger Gustavsson, §Kerstin Hofling, †Ulrika Wahle, and
║Claes €Osterlind, *yGothenburg, zBora� s, xLidk€oping, and ║Trollh€attan, Sweden
Abstract: Objective. A stumbling-block in voice therapy is how the patient will be able to apply the new voice
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technique in everyday life. Possibly this generalization process could be facilitated by giving voice therapy in
group because of the natural forum for training voice-to-speech early in communication between the patients in
a group setting. The aim of the study was to compare treatment results from individual voice therapy and voice
therapy in group, at several time points and in comparison to patients with no voice therapy.
Methods. A randomized treatment study was performed with 77 consecutive patients diagnosed with a func-
tional voice disorder. Thirty-one patients were randomized to individual and group therapy, respectively, and
15 patients to no therapy. The assessments included standardized voice recording and registration of voice range
profile (VRP), answering Voice handicap index (VHI) and visual analogue scales for self-hoarseness and self-
vocal fatigue, and perceptual voice evaluation by speech-language pathologist. The assessments were performed
before, direct after therapy, and three months later in all groups. The 2 therapy groups were also assessed
12 months after therapy.
Results. All VHI scores as well as the self-ratings of hoarseness and vocal fatigue, and the perceptual evaluation
of voice quality and maximum VRP improved significantly in both therapy groups 3 months after treatment and
at 12 months follow-up. There were no significant changes in the control group, with the exception of decreased
self-rated hoarseness and increased maximum VRP. Comparisons between treatment groups showed significant
larger improvement after group therapy for VHI physical subscale at 12 months, as well as significant lower VHI
total score at all measurement sessions and lower subscale scores at 12 months. There were no differences
between treatment groups in self-hoarseness or self-vocal fatigue and no difference in perceptual voice quality or
VRP. Comparison between controls and treatment groups showed significant larger change in treatment groups
from baseline to three months in VHI total and to end of therapy in functional subscale. Treatment groups also
showed significant lower scores than controls at each measurement session, for VHI total and physical subscale
as well as lower degree of perceptual aberration of voice quality and vocal fatigue, at three months follow-up.
Conclusions. This study shows long-term improvement from behavioral voice therapy, particularly in a group
setting. The results indicate the importance of early transfer-to-speech and late posttherapy test to capture
whether the goal of voice therapy was fulfilled or not for the patients.
KeyWords: Voice therapy−Treatment outcome−Group treatment−Individual treatment−Functional voice
disorder.
INTRODUCTION
A voice disorder implies psychosocial and physical limits for
the patient. There is a risk for withdrawing from certain sit-
uations in life because of aberrant voice quality in speech,
or loss of singing voice quality, or not enough breath sup-
port for exercising the sports one used to. The demands of
verbal skill and professional voice use increase in the
ted for publication August 31, 2018.
ng: The study was supported by grants from The Health & Medical Care of
on V€astra G€otaland (VGFOUREG-11402).
the *Occupational and Environmental Medicine, Institute of Medicine, Uni-
f Gothenburg, Gothenburg, Sweden; yDepartment of Logopedics and Phoni-
NT Clinic, Sahlgrenska University Hospital, Gothenburg, Sweden;
ent of Speech Language Pathology, ENT Clinic, Hospital of South of
, Bora
�
s, Sweden; xDepartment of Speech Language Pathology, Hospital of
g, Lidk€oping, Sweden; and the ║Department of Speech Language Pathol-
- Healthcare, Trollh€attan, Sweden.
ss correspondence and reprint requests to Ann-Christine Ohlsson, Depart-
Occupational and Environmental Medicine, Institute of Medicine, University
nburg, SE-405 30 Gothenburg, Sweden.
al of Voice, Vol. 34, No. 2, pp. 303.e17−303.e26
997
8 The Voice Foundation. Published by Elsevier Inc. All rights reserved.
/doi.org/10.1016/j.jvoice.2018.08.023
information and communication society of our time. This is
also obvious within health care where the majority of
patients diagnosed with voice disorders have voice intensive
professions such as teacher, telemarketing personal, manag-
ers, or vocal artists.1−3 Most of these patients are diagnosed
with a functional voice disorder classified as either primarily
(caused by vocal behavior but with no obvious organic
changes in the vocal folds) or as secondary (caused both by
vocal behavior and organic changes in the vocal folds).4
First priority at the hospital is to offer voice therapy to
patients suffering from severe pathological changes in the
voice organ, such as tumors or paresis. This causes patients
with functional voice disorders to have to stand on the wait-
ing list. While waiting longer periods, these patients are at
risk for increased voice problems.
To shorten the waiting time for voice therapy, the preven-
tative voice education in society for voice intensive profes-
sions needs to be developed. Meanwhile the in-clinic voice
therapy methods should be more effective. A Cochrane
https://doi.org/10.1016/j.jvoice.2018.08.023
TABLE 1.
Study Design
Patient information and consent
Randomization (group therapy, individual therapy,
controls)
Assessments before therapy
Six sessions of behavioral voice therapy
Assessments at end of therapy
Assessments three months post therapy
Assessments 12 months post therapy (treatment groups
only)
303.e18 Journal of Voice, Vol. 34, No. 2, 2020
Database Review by Ruotsalainen et al5 shows improve-
ment in voice function with treatment compared with no
treatment. However, the authors point out that the studies
need methods that match the treatment aims better. Also in
a systematic review by Speyer,6 many of the studies had
methodological problems, and it was difficult to generalize
the effect results. Desjardins et al7 came to the same conclu-
sion in a review on behavioral voice therapy effectiveness,
therapy techniques, and therapy results in randomized con-
trolled trials. Results from the reviewed studies generally
showed improvement from voice therapy but the authors
conclude that more research is needed about the clinical
meaningfulness of the therapy results.
The goal of voice therapy is to give the patient strategies
for a more effective behavior in everyday life so that the
voice problem disappears. The great stumbling-block is
how the patient will be able to generalize the new voice tech-
nique outside the therapy room. A typical behavioral voice
treatment program includes voice hygiene, breathing, relax-
ation, vocal exercises, and transfer-to-speech.8,9 Generally
the therapy period is short, with a minimum of treatment
sessions because of long waiting time for voice treatment at
the hospitals. Accordingly, follow-up of the patient's voice
function in everyday situations is strongly limited.
The most common form of in-clinic voice therapy in Swe-
den is individual voice therapy although voice therapy in a
group setting is developing.10 Earlier clinical experiences
indicated that the patients' process of integrating the "new"
vocal behavior in everyday communication could be facili-
tated by delivering the voice therapy in a group setting.11-13
When the participants in a group get individual feedback
from the speech-language pathologist (SLP), eg, in technical
voice exercises or transfer-to-speech, it implies opportunitiesto learn also from the feedback that SLP gives to the others
in the group as well as from the other participants'
responses. Moreover, in a group setting, the opportunities
for spontaneous conversation between the participants are
present through all sessions. If urged by SLP, this situation
offers training for integrating the new voice technique into
ordinary communication with others. Thus, the new voice
technique is applied in natural conversations already at an
early stage of therapy. Results from randomized control
studies of voice therapy in group setups show increased
vocal awareness and decreased voice problems over
time.14,15 However, no randomized studies have been found
where treatment outcomes from voice therapy delivered in a
group setting are compared with outcomes from individual
voice therapy.
The purpose of the study was to compare treatment out-
comes between group and individual modalities of voice
therapy delivery in patients diagnosed with functional voice
disorders. For comparison, a control group which received
no treatment was included.
The following research questions were asked:
(1) Do the treatment outcomes from group therapy differ
in comparison to those from individual therapy?
(2) If improved outcomes in the therapy groups, are they
long standing?
(3) Does voice measurement outcome differ between
patients after voice therapy, either individual or in a
group setting, in comparison with those from control
patients without treatment?
METHODS
Study design
The study was designed as a prospective, block fashion
randomized treatment study. Consecutive patients on the
waiting list for voice therapy were randomized for treat-
ment delivered either in a group setting or in an individ-
ual setting or in a control group with no voice therapy
given during the course of the study. Voice was assessed
before therapy, at the end of therapy, and at three
months post therapy in all the three groups. In the
2 treatment groups, voice was assessed also at 12 months
post therapy (Table 1). Information about the study and
invitation to participate were sent home to consecutive
patients in line for voice therapy at four hospitals in
southwest of Sweden. If the patient consented, the ran-
domization took place. The criteria for inclusion were
Swedish speaking adult, aged 18 to 70 years, with pri-
mary or secondary functional voice disorder referred to
SLP for voice treatment. Severe concomitant disease,
neurological voice disorders, laryngeal cancer, and cogni-
tive impairment were exclusion criteria. The plan was to
continue until at least 30 patients had been included in
each study group.
Subjects
A total of 79 adult subjects with functional voice disorder
were included. Two of them withdrew from the study due to
illness and family reasons, yielding a total of 77 participants
of which 31 subjects had been randomly assigned to individ-
ual voice therapy, 31 to therapy in a group setting, and
15 subjects to a control group. The small number of subjects
in the control group was caused by the decreasing number
of patients on the waiting lists at the four SLP departments,
a spin-off effect of the study. The waiting time to treatment
for the controls was not delayed by the participation in the
Ann-Christine Ohlsson, et al Voice Therapy Outcome 303.e19
study. The distribution of gender and age in the three study
groups is given in Table 2.
Videostroboscopic examination of the larynx was per-
formed by a phoniatrician or an otolaryngologist before
treatment in all subjects. The most frequent diagnosis was
dysphonia without pathologic changes in larynx. Nine per-
cent of the patients were diagnosed with vocal nodules, 5%
with chronic laryngitis, and 4% with gastroesophageal
reflux. Seven percent of the patients were smokers. The dis-
tribution of diagnoses and smokers were equal in the study
groups. About half of the patients in all the three groups
had voice-intensive professions (eg, teacher or other instruc-
tor, telephone service).
All 62 patients in the treatment groups completed the
voice assessment before therapy and at the end of therapy.
One patient in the individual therapy group and one in the
group therapy group did not complete the assessments at
three months post therapy. Four patients in the individual
therapy group and 3 patients in the group therapy group
withdrew from the follow-up assessment at 12 months. In
all, 55 patients participated in the complete study protocol
at 12 months post therapy, 27 in the individual therapy
group and 28 in the group therapy group. All 15 patients in
the control group completed the voice assessment corre-
sponding to before therapy, at the end of therapy and at
3 months post therapy. No follow-up assessment was made
at 12 months post therapy, since these patients received their
planned treatment during this period. Number of respond-
ents at each measurement session is presented together with
treatment results in Tables 3 and 4.
Treatment
Behavioral voice therapy was performed with the partici-
pants of the study at four hospitals in the Western region of
Sweden. The SLPs participating in the study met regularly
in team conferences. These conferences were important for
planning and follow-up of common strategies for treatment
at the four SLP departments.
The primary variable being compared between the two
treatment groups in the study was the modality of delivery,
ie, individual versus group therapy. The rationale for the
study was that both modalities of treatment delivery have
their advantages and disadvantages. Individual voice ther-
apy offers exclusivity, ie, the patient gets all attention from
TABLE 2.
Distribution of Gender and Age in the Three Study
Groups
Individual
Therapy
Group
Therapy
No
Therapy
n = 31 n = 31 n = 15
Age (range), years 48 (24-69) 48 (23-68) 47 (31-61)
Females, n (%) 21 (68) 23 (74) 13 (87)
SLP, but the setting makes it difficult to apply the new voice
technique in natural situations for communication. Voice
therapy in a group setting, on the other hand, offers possi-
bilities to apply the new voice technique in natural commu-
nication with the other group participants, but at the same
time, the patient has to share SLP's attention with others.
Another important difference between the two modalities of
delivery is that patients in individual therapy learn from the
SLP, while in a group setting, the patients also learn from
each other. Care was taken in the study to deliver the voice
therapy individually, ie, the SLP observes each patient in
the group and can deliver individual feedback. To allow
this, it was important to have a small enough number of
participants in the group therapy groups. Number of
patients in each group session in the study varied between
four and five participants. In order to reach each patient in
the group, the group sessions had to be longer than the indi-
vidual sessions. Based on clinical experience, the time span
for group sessions was set to 90 minutes and individual ses-
sions were set to 45 minutes. Each patient had six voice ther-
apy sessions. The sessions were given once a week.
Therapy contents and therapy materials were held similar
between the two therapy groups. Ingredients in therapy con-
tents were voice hygiene, breathing, relaxation, vocal exer-
cises, and transfer-to-speech. Therapy materials consisted of
common word lists and texts. Therapy session contents and
dosages as well as homework contents and dosages were
modified according to the needs of each patient during the
treatment period. The content frame in common for the two
therapy groups in each of the six therapy sessions are shown
below.
Session 1. Voice physiology, vocal hygiene, and voice
ergonomics. Exercises: relaxation and posture, breathing,
and coordination of breathing and voice. Homework: daily
exercising of relaxation and posture, breathing, and coordi-
nation of breathing and voice, according to SLP's prescrip-
tion on a paper sheet.
Session 2. Follow-up and repetition of homework. Exer-cises: voice technique with gestures and in syllables. Subject
outside exercises: vocal hyperfunction and vocal hypofunc-
tion. Homework: daily training with the new voice tech-
nique in syllables from a list.
Session 3. Follow-up and repetition of homework. Exer-
cises: voice resonance and articulation in words and short
phrases. Subject outside exercises: breathiness, creakiness,
and glottal attacks. Homework: daily training of voice reso-
nance and articulation in words and short phrases from a
list.
Session 4. Follow-up and repetition of homework. Exer-
cises: to apply the new voice technique in texts and dia-
logues. Homework: daily training of voice technique in
texts and in a dialogue with a certain person or in a certain
situation.
Session 5. Follow-up and repetition of homework. Exer-
cises: prosody and volume variation, transfer-to-speech,
simulation of everyday situations. Homework: daily train-
ing of transfer-to-speech in everyday situations. Contracts
TABLE 3.
Baseline and Change From Baseline to End of Treatment, and Three Months After Treatment for All the Three Study Groups
Individual Treatment Group Treatment Controls
Variables Baseline
(BL) n = 31
Change
From BL
to End of
Treatment
n = 31
Change
From BL
to 3 m
n = 30
Change
From BL
to 12 m
n = 27
Baseline
(BL)
n = 31
Change
From BL
to End of
Treatment
n = 31
Change
From
BL to 3 m
n = 30
Change
From
BL to 12 m
n = 28
Baseline
(BL)
n = 15
Change
From BL
to End of
Treatment
n = 15
Change
From
BL to 3 m
n = 15
VHI total 38.5
(2.89)
6.87
(1.59)
6.65 (1.60) 7.27 (1.81) 31.9
(2.35)
6.10 (1.59) 8.67 (1.60)† 11.8 (1.79) 37.2
(4.91)
1.80 (2.28) 2.33 (2.28)
P< 0.0001 P < 0.0001 P < 0.0001 P < 0.0001 P < 0.0001 P < 0.0001 P = 0.43 P = 0.31
VHI functional 11.0
(1.13)
2.65
(0.70)‡
2.47 (0.71) 2.40 (0.75) 7.97
(0.99)
1.84 (0.70) 1.94 (0.71) 2.62 (0.74) 8.67
(1.43)
¡0.13 (1.01) 0.13 (1.01)
P = 0.0002 P = 0.0006 P = 0.0015 P = 0.0093 P = 0.0067 P = 0.0005 P = 0.89 P = 0.89
VHI physical 17.7
(1.08)
2.00
(0.75)
2.22 (0.76) 2.31 (0.82) 15.9
(0.94)
1.94 (0.75) 3.49 (0.76) 4.90 (0.81)* 19.5
(1.89)
1.33 (1.08) 1.20 (1.08)
P = 0.0082 P = 0.0038 P = 0.0053 P = 0.0105 P < 0.0001 P < 0.0001 P = 0.22 P = 0.27
VHI emotional 9.71
(1.29)
2.23
(0.64)
1.96 (0.64) 2.60 (0.71) 7.97
(0.99)
2.32 (0.64) 3.23 (0.64)† 4.28 (0.71) 9.07
(1.84)
0.60 (0.91) 1.00 (0.91)
P = 0.0006 P = 0.0025 P = 0.0003 P = 0.0003 P < 0.0001 P < 0.0001 P = 0.51 P = 0.27
Hoarseness
VA scale
55.4
(4.45)
17.1
(4.75)
16.2 (4.80) 11.9 (5.09) 56.0
(4.51)
14.9 (4.75) 14.5 (4.80) 14.3 (5.03) 60.7
(6.80)
8.87 (6.83) 14.7 (6.83)
P = 0.0004 P = 0.0009 P = 0.0201 P = 0.0020 P = 0.0029 P = 0.0049 P = 0.20 P = 0.0322
Vocal fatigue
VA scale
66.3
(4.45)
11.2
(4.61)
22.4 (4.66) 14.7 (4.97) 68.2
(4.61)
12.6 (4.61) 17.4 (4.66) 15.4 (4.91) 75.6
(3.36)
7.53 (6.63) 11.7 (6.63)
P = 0.0160 P < 0.0001 P = 0.0034 P = 0.0067 P = 0.0002 P = 0.0020 P = 0.26 P = 0.08
Voice quality
by SLP VA
scale
37.9
(4.17)
8.09
(3.33)
11.0 (3.36) 12.2 (3.72) 33.7
(3.81)
4.87 (3.33) 12.8 (3.36) 9.30 (3.72) 40.9
(5.40)
0.27 (4.78) 4.93 (4.78)
P = 0.0157 P = 0.0013 P = 0.0011 P = 0.14 P = 0.0002 P = 0.0129 P = 0.96 P = 0.30
VRP maximum
(STdB)
527
(35)
¡156
(32)
¡173 (32) ¡129 (39) 544
(28)
¡175 (35) ¡187 (35) ¡181 (41) 513
(45)
¡116.1 (38.2) ¡127.5 (38.2)
P< 0.0.0001 P < 0.0001 P = 0.0012 P < 0.0001 P < 0.0001 P < 0.0001 P = 0.0030 P = 0.0012
* P < 0.05 for comparison between group treatment and individual treatment.
† P < 0.05 for comparison between group treatment and controls.
‡ P < 0.05 for comparison between individual treatment and controls.
Only treatment groups were assessed at 12 months. Mean, standard error (SE) and P values. Significant differences between groups are denoted with *, †, or ‡. Change within groups. ?Repeated measure-
ment mixed model was used for the statistical analyses. ?No assessment in the control group at 12 months since these patients started their regular treatment after 3 months.
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TABLE 4.
Mean and Standard Deviation (SD) at Baseline, End of Treatment, and Three Months After Treatment for all the Three Study Groups
Individual Treatment Group Treatment Controls
Variables Baseline
n = 31
End of
Treatment
n = 31
Three
Months
n = 30
12 Months
n = 27
Baseline
n = 31
End of
Treatment
n = 31
Three
months
n = 30
12 months
n = 28
Baseline
n = 15
End of
Treatment
n = 15
Three
Months
n = 15
VHI total 38.5 (16.1) 31.6 (17.0) 31.5 (18.1) 27.9 (14.9) 31.9 (13.1) 25.8 (15.3) 23.3 (13.0)*,† 21.0 (11.3)§ 37.2 (19.0) 35.4 (21.2) 34.9 (12.1)
VHI functional 11.0 (6.31) 8.35 (6.17) 8.37 (5.80) 7.74 (6.14) 7.97 (5.52)* 6.13 (4.60) 6.07 (5.16) 5.46 (4.96)* 8.67 (5.55) 8.80 (7.99) 8.53 (6.80)
VHI physical 17.7 (6.02) 15.7 (5.85) 15.4 (6.62) 14.3 (5.66) 15.9 (5.24) 14.0 (6.09)† 12.4 (6.25)║ 11.5 (4.76)§ 19.5 (7.30) 18.1 (6.67) 18.3 (8.15)
VHI emotional 9.71 (7.20) 7.48 (6.75) 7.70 (7.42) 5.85 (5.12) 7.97 (5.49) 5.65 (6.78) 4.77 (4.22) 4.04 (4.10)* 9.07 (7.13) 8.47 (7.69) 8.07 (8.20)
Hoarseness
VA scale
55.4 (24.8) 38.3 (25.3) 38.8 (28.2) 39.8 (25.5) 56.0 (25.1) 41.1 (28.7) 42.0 (27.9) 42.1 (27.6) 60.7 (26.3) 51.9 (30.3) 46.0 (32.2)
Vocal fatigue
VA scale
66.3 (24.8) 55.1 (29.9) 43.3 (28.9)‡ 49.1 (28.0) 68.2 (25.7) 55.6 (27.1) 51.2 (29.1) 53.5 (23.7) 75.6 (13.0) 68.1 (23.2) 63.9 (27.0)
Voice quality
by SLP
VA scale
37.9 (23.2) 29.8 (22.2) 26.2 (25.6) 26.4 (21.6) 33.7 (21.2) 28.9 (21.0) 21.5 (22.6)† 25.1 (20.5) 40.9 (20.9) 40.6 (22.7) 35.9 (25.3)
VRP maximum 527 (192) 683 (238) 699 (206) 702 (197) 543 (157) 718 (190) 731 (133) 707 (238) 512 (174) 628 (200) 640 (236)
* P < 0.05.
† P < 0.05.
‡ P < 0.05 for comparison at each measurement session between individual treatment and controls.
§ P < 0.01 for comparison at each measurement session between group treatment and individual treatment.
║ P < 0.01 for comparison at each measurement session between group treatment and controls.
Only therapy groups were assessed at 12 months. Significant differences between groups at each measurement session are denoted with *, †, or ‡. ?Repeated measurement mixed model was used for the
statistical analyses. ?No assessment in the control group at 12 months since these patients started their regular treatment after three months.
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303.e22 Journal of Voice, Vol. 34, No. 2, 2020
about how to continue ones' own follow-up in daily life after
the ending of the voice therapy period.
Session 6. Follow-up and repetition of homework. Con-
cluding exercises depending on the needs of the patient(s).
Subject outside exercises: patients about continued self-
training and transfer-to-speech in the future.
The main arguments in this study for delivering voice
therapy in a group setting were:
(1) Patients have the opportunity to learn not only from
the SLP's feedback directed to themselves but also
from the SLP's feedback directed to the others in the
group.
(2) Patients have the opportunity to learn from the
other participants in the group when observing
how they modify their responses following the indi-
vidual feedback from the SLP.
(3) Patients can exercise together in tasks. For example,
standing or sitting in a circle exercising vocal sonority
while receiving a syllable or word from one participant
and sending it on to next participant in the circle; or
creating a story together, telling phrases to each other
around the circle while training, eg, how to apply the
new voice technique, or training transfer-to-speech; or
to exercise in pair-wise communication.
(4) Spontaneous conversations between the participants
offer training situations with transfer-to-speech in nat-
ural communication with each other.
(5) Group therapy may imply that the patients discover
that you are not alone having a voice problem, and
theycan support each other and further each other in
performing homework and improvements.
Voice assessment
Routine and standardized procedures for voice recordings
and completion of the questionnaires were conducted at
each of the assessment sessions by an independent SLP at
each of the four hospitals. The assessment SLPs met regu-
larly to plan and follow up of common measurement
routines.
The patients answered a Swedish version of the Voice
handicap index (VHI) which contains 30 statements cover-
ing physical, functional, and emotional aspects of voice.16,17
Examples of statements in the three different aspects are "I
run out of air when I talk” (physical), "I use the phone less
often than I would like” (functional), and "I'm tense when
talking with others because of my voice” (emotional). Each
voice aspect is represented by 10 statements distributed in
random order. The scale for each statement ranges from 0
to 4 (never to always) giving maximal score of 40 for each
voice aspect, in total 120 points (worst possible voice prob-
lems in everyday life). A cut-off score at 20 for VHI total
has been recommended in the literature17 (VHI total score
>20 indicating a voice disorder and VHI total score <20
indicating no voice disorder).
The patients also answered two visual analogue scales
(VA scales), one about self-perceived degree of hoarseness
and the other about self-perceived degree of vocal fatigue.
The assessing SLPs made a perceptual evaluation of the
patients' degree of aberrant voice quality, corresponding to
grade in GRBAS, and denoted their evaluations on a VA
scale. VA scales of 100 mm were used where the left end
was labeled "not at all" and right end "very much." The
assessing SLPs were not involved in the patients' voice
therapy. Before the start of the study, it was decided that
the assessing SLPs should avoid communicating with
patients about the voice therapy, in order to keep them-
selves unaware of which of the study groups each patient
belonged to.
For independent perceptual voice evaluation, the
patients were recorded in a sound proof studio on DAT
Panasonic SV-3800 with rate of signal sampling set at
44 KHz and fixed intensity level while reading aloud a
Swedish standard text (translated/The boy and the
farmer). A head-mounted Sennheiser microphone was
used with 12 cm distance between microphone and
mouth. Two first sentences of the standard text were seg-
mented for the perceptual voice analysis. The voice sam-
ples chosen for comparison within each patient were
before treatment and three months post treatment. The
voice samples in each “pair” were randomized (before
[b] vs. after [a] treatment, eg, ab, ba, aa, bb). Each pair
of voice samples was coded and transferred in random
order to a listener file. Perceptual evaluation was per-
formed by two professional listeners (two of the authors
not involved in the voice therapy or assessments of the
study). First, each listener judged independently from
each other which of the before-after voice sample in
each pair (A, B) had the best voice quality or if no dif-
ference (0) was noticeable. Second, the listeners com-
pared their judgment protocols and in case of difference
in judgments of a voice sample pair they listened
together to reach a consensus.
For an objective measure of extreme voice production,
a phonetogram18 was performed with the patients. The
phonetogram is a graphical representation of the sub-
ject's voice range and flexibility, and features voice out-
put in a graph with voice intensity in dB on the y-axis
and voice pitch in Hz and semitones (ST) on the x-axis.
The equipment used in this study was the Phog com-
puter software (Interactive Phonetography System, Saven
Hitech, Stockholm). Phog derives the outcome measures
automatically. The type of phonetogram or voice range
profile (VRP) registered in the study was one where the
patient produces a sustained [ɑ:] repeatedly in order to
perform as large a voice area as possible during
5 minutes, a maximum VRP. The measurement outcome
is expressed in semitones x decibel (ST*dB). Accessibility
to the Phog software was restricted to only two of the
four hospitals why the number of patients registered was
smaller than for other assessments.
Ann-Christine Ohlsson, et al Voice Therapy Outcome 303.e23
Statistics
Data were analyzed with methods for repeated measure-
ments taking into account group effects, time effects and
interaction between group and time. In the analyses, the
SAS procedure PROC MIXED was used. Estimates of dif-
ferences between the groups at different time points with
P values and confidence intervals were calculated by
Estimate Statements in PROC MIXED. Significance
level = 0.05. Variation in number of observations in the
groups at different time points was corrected for according
to Searle et al.19 The partial correlations given time points
were calculated by the SAS procedure PROCMIXED.
SAS version 9.3, SAS Institute Inc., Cary, NC was used
for all calculations.
The following post hoc analyses were performed: (1)
Power calculation for population size. The analysis
showed that with a two-sided t test and a power of 80%,
31 subjects are needed in each group. Significance
level = 0.05. (2) Calculation of proportion of patients in
the treatment groups changing their VHI total score
from >20 at baseline to <20 at follow-up. Sign test was
used for comparison within groups and Fisher's exact
test was used for comparison between groups. Signifi-
cance level = 0.05.
The study was approved by the Ethics Committee of
the Sahlgrenska Academy at Gothenburg University
(Dnr 540-05).
RESULTS
Outcome within groups
The results of the study show significant improvement of
subjective voice function within both therapy groups. The
VHI total score and the three VHI subscale scores as well as
the self-ratings of hoarseness and vocal fatigue improved
from baseline to end of therapy and to 3 and 12 months fol-
low-up (Table 3). The perceptual evaluation of aberrant
voice quality by assessing SLPs improved from baseline to
end of treatment after individual voice therapy but not after
group therapy. However, both therapy groups improved
from baseline to 3 and 12 months follow-ups. Maximum
VRP improved to end of treatment and to 3 and 12 months
after treatment in both therapy groups. In comparison,
there were no significant changes in the control group, with
the exception of decreased self-rated hoarseness from base-
line to three months post treatment and increased maximum
VRP to end of treatment and to three months follow-up
(Table 3).
A post hoc analysis was also performed to test proportion
of patients that had changed their VHI total score from >20
(indicating a voice disorder) at baseline to VHI total score
<20 (indicating no voice disorder) at 12 months. The results
showed that 39% (P = 0.001) of the patients in the group
therapy group and 30% (P = 0.008) of the patients in the
individual therapy group had changed to normal VHI total
score <20.
Comparison between therapy groups
Comparison between the two therapy groups showed signif-
icantly larger improvement for VHI physical subscale from
baseline to 12 months in the group therapy group in com-
parison to the individual therapy group (Table 3). Compari-
son at each measurement session showed significant lower
VHI total score at 3 and 12 months and lower subscale
scores at 12 months after group therapy compared with
individual therapy (Table 4). There was no significant differ-
ence between therapy groups in outcome from VA scales or
maximum VRP analyses.
Post hoc analysis comparing proportion of patients
changing VHI total score from >20 at baseline to VHI total
score <20 at 12 months showed no significant difference
between the 2 therapy groups.
Comparison between controls and therapy groups
Comparison between controls and the group therapy group
showed significant larger improvement in VHI total and
emotional subscale from baseline to three months post
treatment in the group therapy group (Table 3). Compari-son between controls and group therapy group at each mea-
surement session showed significant lower VHI total score
at three months after treatment and lower physical subscale
score at end of treatment and at three months follow-up in
group therapy group (Table 4). Assessing SLPs' evaluation
of degree of perceptual aberrant, voice quality was also sig-
nificantly lower in group therapy group than in the control
group at three months after treatment.
Comparison between controls and the individual therapy
group showed larger improvement in functional subscale
from baseline to the end of treatment in the individual ther-
apy group (Table 3). Comparison between controls and
individual therapy group at each measurement session
showed significant lower degree of vocal fatigue at three
months in the individual therapy group (Table 4).
There were no differences in change between any of the
study groups for Hoarseness or maximum VRP.
Outcome from voice recording data
The perceptual evaluation from voice recordings before and
three months after voice therapy showed no significant dif-
ferences in change of voice quality between the three study
groups. Voice quality was improved in 34% of the patients
in the individual therapy group and in 32% of the patients
in the group therapy group. At the same time, 30% of the
controls also showed improved voice quality.
Correlations between VHI total score and VA scores for
subjective hoarseness and vocal fatigue were moderate.
Pearson partial correlations showed 0.54 (P < 0.0001) for
hoarseness and 0.44 (P < 0.0001) for vocal fatigue.
DISCUSSION
The main purpose of the study was to compare effect from
individual voice therapy and voice therapy in group in
303.e24 Journal of Voice, Vol. 34, No. 2, 2020
patients diagnosed with functional voice disorder. Change
within and between groups was compared from baseline to
end of treatment and to 3 and 12 months follow-up. The
study was completed by comparing outcome at the same
time points from controls without voice therapy.
There was no difference between groups in distribution of
subdiagnoses, smoking, or voice intensive professions.
Mean age was around 50 years and women were in majority
in each group. Mean baseline measures did not differ
between the three study groups except VHI functional sub-
scale which was significantly lower in the group therapy
group compared with the individual therapy group. Mean
baseline measures for VHI total score (31.9-38.5) and VA
scales for hoarseness (55.4-60.7 mm), vocal fatigue
(66.3-75.6 mm), and grade of perceptual vocal aberration
(33.7-40.9 mm) or maximum VRP (512-543 ST*dB) showed
no difference between groups. The range in baseline scores
corresponds well with the results in a study by Ohlsson and
Dotevall17 for VHI and VA scales in patients suffering from
functional voice disorder and of same age as in this study.
The VHI total measures are also in correspondence with
results from a study by Holmberg et al18 in which women
with diagnosed functional voice disorder scored 33 on VHI
total.
Change within therapy groups
Results from the study showed significant changes from
baseline within both therapy groups. Except for perceptual
voice quality at end of treatment in the group therapy
group, all variables improved to end of therapy and to fol-
low-ups at 3 and 12 months post treatment. Also, 39% of
the patients in group therapy group and 30% of the patients
in the individual therapy group had decreased their VHI
total score below 20 at 12 months, placing them in the nor-
mal total score range. In a clinical evaluation study using
similar measurement variables as in the present study,
Abrahamsson et al10 also found significant improvement
after both individual voice therapy and group therapy at
follow-ups around 12 months posttherapy. The long-term
results from these two studies indicate that it may be impor-
tant to give the patient time for transfer of the new voice
technique into everyday life and to postpone the postther-
apy test till some time has lapsed after end of therapy. Possi-
bly, this time for self-transfer could be regarded as a
component of the voice therapy process. In a study by Behr-
man et al,20 comparing outcomes from voice therapy in
comparison with voice hygiene education, the authors con-
clude that self-study may be an important part of therapy.
They found a significantly larger improvement also after
four weeks of postself-study in the patients receiving voice
therapy. In our study as well as in the study by Abrahams-
son et al,10 the time-lapse to follow-up were longer. Possibly
a time-lapse of three months to the posttherapy test could
be a moderate choice, according to the data in the present
study.
Comparison between therapy groups
Comparison of change between therapy groups was the
main goal of the study. The results showed larger improve-
ment from baseline to 12 months for VHI physical subscale
in the group therapy group. Comparison at each measure-
ment session after voice therapy also showed lower VHI
scores at 12 months after group therapy than after individ-
ual therapy. As VHI functional subscale already at baseline
had significant lower score in group therapy than in individ-
ual therapy, the difference in score in functional subscale
between groups at 12 months could be considered as redun-
dant (Table 4). However, although there was no significant
group difference at baseline for either VHI total or physical
or emotional subscales, there were significant lower scores
at 12 months in the group therapy group compared with the
individual therapy group.
Probably the favorable long-term results from group ther-
apy in comparison with those from individual therapy indi-
cate some therapeutic advantage in group setup in
comparison with individual setup. For the patients in group
therapy, each therapy session was twice as long as for indi-
vidual therapy, 90 minutes versus 45 minutes. However, the
longer time spent in group sessions in comparison with indi-
vidual sessions was necessary to carry through the kind of
group voice therapy presented in this study. The sessions
were mainly set up for dynamic group activities and not
class-like teaching. Thus, a possible interpretation of the
more favorable long-term results after group therapy could
be that it was an effect of long enough sessions for the
patients to learn both from SLP's and each other's
responses, as well as learning from more frequent and early
training of transfer-to-speech in everyday communication
with each other. Ziegler et al21 asked in their study
45 patients, posttherapy, what facilitators and barriers they
found had influenced voice therapy effectiveness. A major-
ity of the patients answered specific exercises and transfer-
to-speech as facilitators. At the same time, many patients
found generalizing the new vocal behavior as a barrier to
voice therapy effectiveness. The authors conclude the
importance of introducing transfer-to-speech early in the
therapy process.
Abrahamsson et al10 found no significant difference in
therapy outcome between groups. Possibly the difference in
group therapy settings could explain the difference in out-
come between our studies. In the study by Abrahamsson
et al, group therapy was performed in an open group setup,
ie, group participants and SLPs shifted from time to time.
In the present study, each group setting consisted of the
same participants and SLP through all six therapy sessions.
Co-working between participants over time in certain voice
exercises as well as transfer-to-speech was emphasized in
the group settings in our study. Law et al22 studied with pro-
spective case series the effectiveness of group voice therapy
for dysphonic teachers in a group climate perspective. They
found that an engaging group climate plays a significant
role for treatment success. It is possible that the closed setup
Ann-Christine Ohlsson, et al Voice Therapy Outcome 303.e25
for group therapy groups in the present study facilitated a
group climatewhere the participants support each other.
Outcomes in the control group
In the control group, there was no improvement except for
decreased hoarseness and increased maximum VRP. Possi-
bly the decrease in hoarseness could be explained by regres-
sion toward the mean, in this case that high values at
baseline preferably move in the direction of lower values at
follow-up. The increase of maximum VRP could be
explained as a training effect from repeated assessments.
Comparison between controls and therapy groups
As expected, comparison between controls and therapy
groups showed significant larger change in therapy groups.
However, the differences were shown for VHI scores but
not for VA scales (hoarseness, vocal fatigue, and perceptual
voice quality) or VRP max. On the other hand, comparison
at each measurement session showed significant lower
scores also in VA scales for vocal fatigue and perceptual
voice quality in the therapy groups compared with controls,
but no difference between controls and therapy groups for
outcome in hoarseness or maximum VRP. In this study,
correlation between the results from VHI and VA scales for
hoarseness and vocal fatigue was only moderate. Also ear-
lier studies have found low-to-moderate correlation between
VHI scores and other subjective, perceptual, or acoustic
measurements of voice.17,23,24 Schindler et al25 conclude
from their study that VHI and voice laboratory measure-
ments give independent information. Thus, the difference
between the study groups in VHI outcome but not in VA
scales outcome possibly shows that different aspects of voice
dysfunction are assessed. VHI refers to everyday experien-
ces of physical and psychosocial impact of the voice disor-
der, while self-ratings of hoarseness and vocal fatigue are
related to subjective vocal symptoms.
Outcome from voice recording data
The perceptual evaluation from the voice recordings before
and three months after voice therapy showed no significant
differences in change of voice quality between the three
study groups. Already at baseline, the voices of the patients
in this study sounded normal or close to normal. Typical
for a functional voice disorder is the patient's experiences of
dysfunction like sensation of pain or lump in the throat,
strained or tired voice, while at the same time, abnormality
in voice quality is harder to detect. A study by Steen et al26
assessed the responsiveness to change of several measures
posttherapy in patients with functional voice disorder. They
found that measures of self-reported voice function (among
them VHI) showed larger effect sizes following voice ther-
apy compared with the effect sizes from perceptual evalua-
tion. Ziegler et al21 found that VHI scores were correlated
with patient-reported improvement from voice therapy.
Also, Richter et al27 found improved voice quality
compared with controls in a group of student teachers who
had participated in a voice training program. However, the
trained group reported similar increase in vocal strain as the
controls. In this case, there seemed to be a contradiction
between results in voice quality and voice symptoms.
Weaknesses of the study
A weakness in this study is the small size of the control
group, 15 patients. During the progress of the study, the
waiting time for voice therapy was shortened at the partici-
pating hospitals, and patients could start regular voice ther-
apy earlier than expected. This was a positive spin-off effect
of the study and from ethical reasons the size of the control
group became smaller than planned. Possibly differences in
results between controls and therapy groups have been
affected by this.
More, although it was presupposed that assessment SLPs
would be unaware of which study group each patient
belonged to, it is possible that they at some point got such
information unintentionally, which in that case could have
influenced their evaluation of degree of perceptual aberrant
voice quality in a patient.
CONCLUSIONS
The evidence from this study is that patients with functional
voice disorders improve with behavioral voice therapy,
especially in a group setting. The goal of voice therapy is to
give the patient tools for long-term change of the vocal
behavior in everyday life so that the voice problem disap-
pears. This study shows long-term improvement from voice
therapy, particularly in a group setting. The results indicate
the importance of early transfer-to-speech and late postther-
apy test to capture whether the goal of voice therapy was
fulfilled or not.
Acknowledgments
The authors wish to acknowledge speech-language patholo-
gist Christina Lindhe for co-working in the study. Our
acknowledgments also go to our assessment colleagues and
to Kjell Pettersson, Eva M Andersson, and Nils-Gunnar
Pehrsson for statistical consultations.
SUPPLEMENTARY DATA
Supplementary data related to this article can be found
online at doi:10.1016/j.jvoice.2018.08.023.
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	Voice Therapy Outcome-A Randomized Clinical Trial Comparing Individual Voice Therapy, Therapy in Group, and Controls Without Therapy
	INTRODUCTION
	METHODS
	Study design
	Subjects
	Treatment
	Voice assessment
	Statistics
	RESULTS
	Outcome within groups
	Comparison between therapy groups
	Comparison between controls and therapy groups
	Outcome from voice recording data
	DISCUSSION
	Change within therapy groups
	Comparison between therapy groups
	Outcomes in the control group
	Comparison between controls and therapy groups
	Outcome from voice recording data
	Weaknesses of the study
	CONCLUSIONS
	Acknowledgments
	Supplementary data
	References