Vocal Fatigue: Updated Definitions, Measures, and Treatment Strategies : Vocal Fatigue: Updated Definitions, Measures, and Treatment Strategies Nancy Pearl Solomon, Ph.D., CCC-SLP
Research Speech-Language Pathologist
Nancy.P.Solomon@US.ARMY.MIL
Army Audiology & Speech Center
Walter Reed Army Medical Center The opinions or assertions contained herein are the private views of the Author and are not to be
construed as official or as reflecting the views of the Department of the Army or the Department of Defense.
International Perspectives : International Perspectives Voice disorders viewed as an issue of occupational safety and health
Finland (Vilkman, Sala, Rantala, Vintturi, Jónsdottir, …)
Australia (Russell, Oates, Mattiske, Greenwood)
USA (McCabe, Roy, Smith, Titze, Verdolini, …)
Poland
Sweden
Iceland
Belgium
Brazil
The Netherlands
What is Vocal Fatigue? : What is Vocal Fatigue? “…a frequent descriptor for a well-known set of symptoms…”
(Stemple, Glaze, & Klaben, 2000)
Common Symptoms of Vocal Fatigue : Common Symptoms of Vocal Fatigue Increased vocal effort and discomfort
Reduced pitch range and flexibility
Reduced vocal projection (power)
Reduced control of vocal quality
Symptoms increase across the speaking day
Improvement after resting (Colton & Casper, 1996; Gotaas & Starr, 1993; Stemple, Glaze, & Klaben, 2000)
Vocal Fatigue By Any Other Name… : Vocal Fatigue By Any Other Name… “vocal attrition” … (Sapir, 1993)
“a temporary decrement of vocal function with vocal use” (Sivansankar & Fisher, 2003)
“… a vocal loading-borne change manifested as physiological, perceptual, or subjective changes.” (Vintturi, 2001)
Vocal Loading as a Continuum : Vocal Loading as a Continuum (Vintturi, 2001; Vilkman, 2004) Vocal loading: prolonged use of voice
Vocal warm-up: occurs at the beginning of vocal loading
Post-loading short vocal rest: a break in vocal loading
Regarded as phases on a continuum
Phonatory Effort Increases With Vocal Fatigue : Phonatory Effort Increases With Vocal Fatigue “… a progressive increase in phonatory effort accompanied by a progressive decrease in phonatory capabilities.”
(McCabe & Titze, 2002)
Fatigue is …
“… a progressive increase in the effort required to exert a desired force and the eventual progressive inability to maintain this force in sustained or repeated contractions.” (Enoka & Stuart, 1985)
Definition of “Pure” Vocal Fatigue : Definition of “Pure” Vocal Fatigue The client reports a change in the way the voice feels or sounds during or after prolonged vocal use
Symptoms include vocal tiredness, effort, discomfort, reduced function
Acoustic, perceptual, and anatomical changes are subtle and nonspecific
Improvement with vocal rest
Absence of vocal lesions
Absence of dysphonia
Fatigue Mechanisms : Fatigue Mechanisms Central
Peripheral
Potential Mechanisms of Vocal Fatigue : Potential Mechanisms of Vocal Fatigue Central (mental) fatigue
Report of tiredness
Sense of effort
Peripheral (muscle) fatigue
Laryngeal
Respiratory
Biomechanical properties of tissue
Stress and strain
Viscosity
Vocal Effort : Vocal Effort A common complaint in vocal fatigue
Respiratory effort
Increases with expiratory and inspiratory loading
(Gandevia, Killian, & Campbell, 1981; Supinski, Clary, Bark, & Kelsen, 1987; Suzuki, Suzuki, Ishii, Akahori, & Okubo, 1992)
Phonatory effort
Increases with vocal loading
(Stemple, Stanley, & Lee, 1995; Solomon & DiMattia, 2000; Chang & Karnell, 2001; Vilkman, 2004)
Intrinsic Laryngeal Muscles : Intrinsic Laryngeal Muscles Largely fatigue resistant
Human intrinsic laryngeal muscle fiber types
Type I (nonfatiguable) 54%
Type IIa (fatigue resistant) 37%
Type IIb (fatiguable) 6%
(Claassen & Werner, 1992)
Muscle stimulation in anesthetized dogs
Thyroarytenoid muscle was nonfatiguable after 1 hour (Cooper & Rice, 1990)
Respiratory Muscle Fatigue : Respiratory Muscle Fatigue Unless performing whole body exercise at very high intensity levels, the respiratory muscles are unlikely to fatigue
(Dempsey & Babcock, 1995;
McKenzie & Bellemare, 1995)
Nonmuscular Tissue Fatigue : Nonmuscular Tissue Fatigue Vocal fold cover = epithelium, and superficial and intermediate layers of lamina propria
Stress relaxation can lead to increased vocal fold strain (lengthening) and compensatory adjustments to increase tension (based on Hirano, 1974)
Tissue Viscosity & Hydration : Tissue Viscosity & Hydration The fluids in and around the vocal folds act as a mechanical lubricator and shock absorber
Internal (systemic) and external (superficial) hydration can affect vocal fold viscosity
Prolonged, high-pitched phonation leads to increased frictional energy loss, increased heat dissipation, and increased tissue viscosity (Cooper & Titze, 1985; Hammond, Zhou, Hammond, Pawlak, & Gray, 1997; Titze, 1994)
Conceptual Model of Vocal Fatigue : Conceptual Model of Vocal Fatigue (McCabe & Titze, 2002)
Vocoergonomics : Vocoergonomics Premise
View occupational voice problems as an occupational safety and health (OSH) issue
Training to improve vocal technique often is not economically or practically feasible
Vocoergonomic (Loading) Factors
Air quality (humidity, cleanliness)
Noise (output level, background, reverberation)
Posture (sitting, standing)
(Vilkman, 2004)
Who Is At Risk For Voice Disorders? : Who Is At Risk For Voice Disorders? Teachers (Roy et al., 2004; Russell et al., 1998; Sala et al., 2001, 2003; Smith et al., 1998; Vilkman, 2004)
Telemarketers (Jones et al., 2002)
Drill sergeants (Mann et al., 1999)
Auctioneers (McHenry & Carlson, 2004) (Fritzell, 1996; Titze, Lemke, & Montequin, 1997)
Teaching Requires How Much Phonation??! : Teaching Requires How Much Phonation??! Phonation occurs 15-40% of the time during a teaching day
Vocal folds vibrate ~1,000,000 times per teaching day for women teachers, and about half as much for men
Obvious potential for phonotrauma (Vilkman, 2004)
Laboratory versus Field Research : Laboratory versus Field Research Laboratory studies
Controlled vocal-loading tasks
Non-portable equipment
e.g., videostroboscopy, aerodynamics
Sound-treated, controlled environment
Field studies
Performance, work day, …
Portable equipment
e.g., voice accumulators, rating scales
Ecologically valid
Experimentally Induced Vocal Fatigue : Experimentally Induced Vocal Fatigue Vocal change occurs after 1-2 hours
Based on vibrational exposure to tissue, safe vocal performance time for reading is estimated to be ~ 35 minutes (Titze, Švec, & Popolo, 2003)
Inconsistent changes in acoustic parameters and laryngeal features
changes in speaking pitch
acoustic instabilities
unusual glottal configuration
laryngeal edema
Selecting Measures for Vocal Fatigue Studies : Selecting Measures for Vocal Fatigue Studies Acoustic and auditory-perceptual
Inconsistent findings from previous literature
Too much variability to be informative
Visual perceptual
Suggestions of unusual glottal configurations
Should reveal muscular and nonmuscular changes
Selecting Measures for Vocal Fatigue Studies : Selecting Measures for Vocal Fatigue Studies Effort perception
Affected by vocal loading
Should reflect central fatigue
Aerodynamics
Depend on respiratory-laryngeal interaction
Should reflect biomechanical properties of nonmuscular laryngeal tissue
Phonation Threshold Pressure (PTP, Pth ) : Phonation Threshold Pressure (PTP, Pth ) The minimum lung pressure required to initiate vocal fold oscillation
Determined by static, vibratory, and viscous properties of the vocal folds
Measured orally (noninvasive)
May correspond with “ease of phonation” (Titze, 1988, 1992)
An “unhappy triad” : An “unhappy triad” Vilkman (2004) proposed that
Elevated phonation threshold
Heightened vocal fundamental frequency
Increased effort
Represent the greatest risk to vocal health
Vocal Loading & Vocoergonomics : Vocal Loading & Vocoergonomics 80 young adults
Three 45-min reading sessions
45-min lunch break
Two 45-min reading sessions
Conditions (n = 5 each)
Male or female
High or low output
High or low humidity
Sitting or standing (Vintturi et al., 2003; Vilkman, 2004)
Vocal Loading & Vocoergonomics : Vocal Loading & Vocoergonomics Questionnaire (17 items; score 0-10)
Factor 1: central fatigue
I love it …………………… I don’t like it anymore
I am doing well ……… I am tired
Factor 2: symptoms of the neck, shoulders, and back
Factor 3: drying in the mouth and throat
Factor 4: symptoms of the throat
Factor 5: symptoms of the voice
Increase in all factors before lunch
Slight reduction in all factors after lunch EXCEPT central fatigue (Vintturi et al., 2003; Vilkman, 2004)
Slide28 : Factor 1: central fatigue
Factor 2: symptoms of the neck, shoulders, and back
Factor 3: drying in the mouth and throat
Factor 4: symptoms of the throat
Factor 5: symptoms of the voice
(Vintturi et al., 2003)
Vocal Loading and Voice Measures : Vocal Loading and Voice Measures Changes from morning to afternoon
Increased SPL
Increased intraoral (subglottal?) pressure
Increased amplitude of flow
Increased peak amplitude of differentiated flow
Indicates increased effort and phonatory threshold.
Effects reduced after lunch break
(Vilkman, Lauri, Alku, Sala, & Sihvo, 1999; Vilkman, 2004)
How Can the Voice Be Prepared for Vocal Loading? : How Can the Voice Be Prepared for Vocal Loading? Will drinking water help?
Is a more humid environment beneficial?
What about vocal warm-up exercises?
Do breaks help? How long? How often?
Hydration Studies: PTP increases with dehydration : Hydration Studies: PTP increases with dehydration systemic and superficial combined
(Verdolini-Marston et al., 1990; Verdolini et al., 1994)
systemic alone
(Finkelhor et al., 1988; Verdolini et al., 2002; Fisher et al., 2001)
superficial alone
(Verdolini et al., 1996; Jiang et al., 1999; Roy et al., 2003; Sivasankar & Fisher, 2002, 2003)
Vocal Loading and Systemic Hydration : Vocal Loading and Systemic Hydration Do PTP and self-perceived phonatory effort (PPE) increase after a prolonged loud-reading task?
Do these changes vary with drinking water?
Do these changes differ between women and men? (Solomon & DiMattia, 2000; Solomon,
Glaze, Arnold, & van Mersbergen, 2003)
Method : Method 4 women and 4 men with normal voices
Hydration conditions: low, high, typical
Read loudly for 2 hours
Measures
PTP
Self-perceived phonatory effort (PPE)
Laryngeal imaging
(Solomon & DiMattia, 2000; Solomon,
Glaze, Arnold, & Van Mersbergen, 2003)
Results : Results PTP increased for all 8 participants
PTP tended to
increase more
or earlier in the
low-hydration
condition for
women 80% of pitch range (Solomon & DiMattia, 2000; Solomon et al., 2003)
Results : Results An anterior gap or spindle-shaped glottis was observed after loud reading for half of the samples
No differences between sexes or hydration conditions for vibratory closure pattern
(Solomon & DiMattia, 2000; Solomon et al., 2003)
Vocal Loading and Superficial Hydration : Vocal Loading and Superficial Hydration Five 45-min sessions of oral reading
40 young adults in each of two conditions
Different seasons in Helsinki, Finland
High humidity: Sept-Dec
65% +5%
Allowed to drink water
Low humidity: January
25% +5%
No water to drink before lunch (after 3 loading sessions)
Aided by a vaporizing humidifier (Vinturri et al., 2003)
Effects of Ambient Humidity : Effects of Ambient Humidity Results pooled over the entire test day
More severe symptoms for low-humidity group
Greater differences seen when examining loading sessions separately, especially for women
(Vinturri et al., 2003) Low
High
Vocal Loading, Systemic Hydration, and Vocal Rest : Vocal Loading, Systemic Hydration, and Vocal Rest Method
20 karaoke singers
Water and rest periods (n = 10)
No water, no rest periods (n=10)
Continuous karaoke singing
Results
Group with water and rest periods sang longer
Group without water or rest
Jitter increased
Highest pitch decreased
(Yiu & Chan, 2003)
Vocal Warm-Up Activity : Vocal Warm-Up Activity 10 minutes of oral reading
No differences
(Solomon & DiMattia, 2000)
45 minutes of oral reading (high and low output)
Many differences, depending on gender and type of phonation
Differences attributed to warm-up effect
(Vilkman, 2004; Vintturi, 2003)
Vocal Warm-Up Exercises : Vocal Warm-Up Exercises Recommended to reduce the occurrence or severity of vocal fatigue
(Blaylock, 1999; Elliot, Sundberg,
& Gramming, 1995)
Based on principles of fatigue prevention from the sports medicine literature
Warm-Up Exercises : Warm-Up Exercises Presumed to (Safran, Seaber, & Garrett, 1989)
Increase blood circulation
Increase respiration
Warm up muscles
Decrease muscle viscosity
Improve muscle contraction
Increase muscle elasticity
Effects are apparent after brief exercise
Improved general muscle function after 20-30 minutes
(Kulund & Töttössy, 1983)
Vocal Warm-Up Exercises : Vocal Warm-Up Exercises Elliot, Sundberg, & Gramming (1995)
10 amateur singers
30 min vocal warm-up exercises
Voices felt better
Inconsistent changes in PTP
Motel, Fisher, & Leydon (2003)
10 trained sopranos
10 minutes vocal warm-up exercises
PTP increased at high pitch
No significant change in pitch range
Vocal Warm-Up Exercises and Vocal Fatigue : Vocal Warm-Up Exercises and Vocal Fatigue 8 women with vocal fatigue
15-20 minutes of vocal preparation
warm-up exercises
vocal rest and relaxation
1 hour of loud oral reading
Measures
Phonational threshold pressure
Phonatory effort
(Milbrath & Solomon, 2003)
Vocal Warm-Up Exercises (Milbrath & Solomon, 2003) : Vocal Warm-Up Exercises (Milbrath & Solomon, 2003) Respiration
Stretching
Breathing
Resonance
Humming
Phonation
Vocal Function Exercises (Stemple et al., 2000)
Results PTP : Results PTP Mean data (N=8)
Results : Results Warming up the voice did not benefit vocal function, as assessed by PTP and PPE
Negative results could relate to habitual phonation styles in persons with chronic vocal fatigue
One brief warm-up session was probably inadequate
One hour of loud phonation was probably inadequate
Now what?? : Now what?? What if vocal warm-up exercises are trained and performed for weeks?
Conditioning Exercise : Conditioning Exercise Purpose: To increase
Strength
Flexibility
Endurance
Methods include
Stretching
Resistance training
Aerobic conditioning
Vocal Function Exercises (VFE) : Vocal Function Exercises (VFE) Developed by Stemple and colleagues (1994)
Intended to improve strength, endurance, and coordination
Strives to balance the subsystems of voice production (respiratory, phonatory, resonatory)
Recommended schedule:
twice daily
6-8 weeks
systematic taper
Effectiveness of Vocal Function Exercises for Normal Voices : Effectiveness of Vocal Function Exercises for Normal Voices 35 women with no voice disorders
4 weeks
Vocal function exercises
Placebo exercises
No exercises
Improved maximum phonation duration and pitch range after vocal function exercises
(Stemple, Lee, D’Amico, & Pickup, 1994)
Similar improvements in 10 singers
(Sabol, Lee, & Stemple, 1995)
Effectiveness of Vocal Function Exercises : Effectiveness of Vocal Function Exercises 58 teachers with voice disorders
6 weeks, with appointments every 2 weeks
Vocal function exercises, n = 19
Vocal hygiene, n = 20
No treatment, n = 19
After vocal function exercises
Reduced score on the Voice Handicap Index
Reported overall voice improvement
Greater ease and clarity for speaking and singing (Roy, Gray, Ebert, Dove, Corbin-Lewis, & Stemple, 2001)
Chant Therapy for Teachers with Vocal Fatigue : Chant Therapy for Teachers with Vocal Fatigue 4 teachers with > 4 years of vocal fatigue
6 1-hr sessions over 2 weeks
Chant therapy
Physiologic recovery treatment (placebo) (McCabe & Titze, 2002)
Chant Therapy : Chant Therapy A type of singing exercise
Gregorian chant pattern
Selected higher than typical pitch
(McCabe & Titze, 2002)
Chant Therapy for Teachers with Vocal Fatigue : Chant Therapy for Teachers with Vocal Fatigue Vocal-loading task
2 hours of loud reading
Chant therapy: Response to vocal loading
Smaller changes in vocal effort and quality
Faster recovery (McCabe & Titze, 2002)
Resonant Voice Therapy (RVT) : Resonant Voice Therapy (RVT) Developed by Verdolini (2000), based on Lessac (1997)
Intended to achieve a strong, clear voice with little effort
Strives to achieve vibratory sensations in the facial bones and minimal vocal fold impact
Recommended schedule
weekly therapy
twice daily home practice
8 weeks
Effectiveness of Resonant Voice Therapy : Effectiveness of Resonant Voice Therapy 13 women with vocal nodules
9 sessions in 2 weeks
Resonant voice therapy + Vocal Hygiene
Confidential voice therapy + Vocal Hygiene
Vocal Hygiene
Both resonant voice therapy and confidential voice therapy were successful
IF used!! (Verdolini-Marston, Burke, Lessac, Glaze, & Caldwell, 1995)
Effectiveness of Resonant Voice Therapy : Effectiveness of Resonant Voice Therapy 64 teachers with voice disorders
6 weeks
Resonant voice therapy, n = 19
Voice amplification, n = 25
Respiratory muscle training, n = 20
Resonant voice therapy and Voice amplification
Reduced scores on Voice Handicap Index
Reduced self-ratings of severity
Voice amplification
Improved overall voice, vocal clarity, ease (Roy, Weinrich, Gray, Tanner, Stemple, & Sapienza, 2003)
Using Amplification : Using Amplification 44 teachers with voice difficulties
Groups
Voice amplification, n = 15
Vocal hygiene, n = 15
No treatment, n = 14
Measures
Voice Handicap Index
Voice Severity self-rating scale
Acoustic measures (Roy, Weinrich, Gray, Tanner, Toledo, et al., 2002)
Using Amplification : Using Amplification Amplification group:
significantly reduced VHI, self-rated severity, jitter, and shimmer
greater vocal clarity, ease, and compliance (Roy, Weinrich, Gray, Tanner, Toledo, et al., 2002*)
[*see related Letter to the Editor by Dworkin et al., and response by Roy et al. in JSLHR, 47, 353-365]
Using Amplification : Using Amplification 5 teachers with voice difficulties
Protocol
Recorded at the beginning and end of one day
Cordless sound amplification for > 1 week
Recorded with amplification
Measures
F0
SPL
F0 and SPL increased both days
Greater increases with amplification
Greater ease and less fatigue with amplification (Jónsdottir, Laukkanen, & Vilkman, 2002)
Using Amplification : Using Amplification Amplification promotes greater vocal ease and comfort
Suggest that increased F0 and SPL are adaptive to vocal loading and may “promote effective voice production” (Jónsdottir et al., 2002, 2003)
Prevention and Training : Prevention and Training 2-day Vocal Training course
Lectures about voice, resonance, & articulation
Vocal exercises
1-day Speech Communication seminar
38 women, 10 men
Call-center customer service advisors
Environment: quiet, dry (19% humidity)
No chronic voice problems; some mild symptoms
(Lehto, Rantala, Vilkman, Alku, & Bäckström, 2003)
Prevention and Training (Lehto et al., 2003) : Prevention and Training (Lehto et al., 2003) Questionnaires
11 symptoms (e.g., fatigue, hoarse, dry, …)
1 item re: change with training
23 statements about the training course
Before training
Most common symptom: need to clear mucus
Other: dry throat, voice fatigue, hoarseness
After training
50% reported reduction in need to clear throat
60% reported improvement in vocal habits
60% of women reported less vocal fatigue
Prevention and Training : Prevention and Training 55 teachers-in-training, no voice problems
Groups
Control, n = 23
Indirect training (1 lecture), n = 20
Direct training (1 lecture + 1 technique), n = 12
Measures
Dysphonia Severity Index (Wuyts et al., 2000)
Vocology Screening Profile (Hazlett, 2001)
Voice Handicap Index (Jacobson et al., 1997)
No significant differences (Duffy & Hazlett, 2004)
Take-home messages : Take-home messages Vocal fatigue ...
Is self-perceived and may not be heard
Occurs over time with vocal use
Involves an increased sense of vocal effort
Is viewed as an issue of occupational safety and health
Is affected by environmental factors
Take-home messages : Take-home messages Vocal fatigue benefits from …
Not vocal hygiene or respiratory training alone
Not one brief session of vocal warm-up exercises
Maybe drinking water for some people
Maybe a humid environment
Probably amplification
Probably providing periods of vocal rest
Probably a vocal conditioning/training program
2-8 weeks
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