How Breakdowns Result in Voice Disorders
Vocal Folds (also called Vocal Cords)
“Fold-like” soft tissue that is the main vibratory component of the voice box; comprised of a cover (epithelium and superficial lamina propria), vocal ligament (intermediate and deep laminae propria), and body (thyroarytenoid muscle)
Glottis (also called Rima Glottides)
Opening between the two vocal folds; the glottis opens during breathing and closes during swallowing and sound production
Voice disorders refer to breakdowns in the vibratory system. Breakdowns can affect any one or all of the three subsystems of voice production.
Air Pressure System
If the airflow source is weak or inefficient (making it difficult to push enough air out of lungs), the voice will be weak and hampered by shortness of breath.
- For example: Patients with asthma, lung cancer, emphysema and other lung conditions often find it difficult to speak loud or for long periods of time.
Any compromise or change to vocal fold vibration causes hoarseness and other voice symptoms.
- For example: Patients with stiffness in the vocal folds from swelling from a common cold develop hoarseness.
- For example: When focal folds cannot come perfectly together from partial nerve input loss, air leak occurs and the voice is “breathy.”
Resonating System or Vocal Tract
A breakdown of the vocal tract can affect voice quality.
- For example: When nasal passageways are swollen and inflamed during the “common cold,” the voice takes on a nasal quality.
Making Sense of It All
The following are a few examples depicting how breakdowns result in voice disorders and a few of the many possible voice symptoms.
Correlating Anatomy, Voice Function, Abnormalities, and Possible Voice Disorder Symptoms
|A Glimpse – “who does what” in Sound Production
|Examples of “Breakdowns” that Affect Sound Process
|Generating Air Pressure
Coordinated functions of diaphragm, abdominal and chest muscles, lungs and chest cavity move air column upwards through vocal folds
|Diaphragm, abdominal and chest muscles move air into and out of lungsLungs are the organs for airBronchi and trachea are the passageway for air from lungs
|Lung diseaseAirway obstruction: asthma, subglottic stenosisParesis/paralysis of muscles
|Shortness of breathWeak voice
Position of vocal folds
|Vocal Fold Position Critical
Vocal folds are in closed position for speech or singing
[Note: Vocal folds are open for breathing]
|Laryngeal muscles contract to close vocal foldsArytenoid cartilages pivot to move vocal folds towards midline [“closed”]RLN and SLN bring nerve inputs to musclesVocal fold mass and edge contribute to glottic closure
|Paresis/paralysis – RLN/SLNMuscle weaknessNeurological diseases; muscular disordersArytenoid arthritisVocal fold granulomaVocal fold nodules, polyps, cystsVocal fold atrophyVocal fold scarring
|HoarsenessBreathinessEffortful phonationVocal fatigueDiplophonia
Vocal Fold Vibration Produces Voiced Sound
|Wavelike Vibration from Bottom to Top–repeat vibratory cyclesWith each vocal fold vibratory cycle, a puff of air escapes, producing voice sound (“buzzy sound”)Singing voice produces unique sound spectra (singing formants) that are distinct from spoken voice
|Superficial lamina propria is the main vibrating layer in vocal fold mucosaVocal fold pliability is critical for vibrationVocal fold surface integrity allows mucosal wave propagationVocal fold mass and edge contribute to glottic closure
|Vocal fold scarVocal fold lesions: cysts, nodules, polyps, papillomaVocal fold granulomaSwelling and inflammation (reflux laryngitis, viral laryngitis)Reinke’s edemaParesis/paralysisHemorrhage, vascular ectasias
|HoarsenessEffortful phonationWeak voiceSpeaking voice lower than usual”Vocal fry”Voice fatigue
Voice Volume or Loudness
|Amplitude of Sound Waves
Loudness is achieved by:Increasing air pressure/flowIncreasing vocal fold resistance
|Breath supportLaryngeal muscles contract to adjust tension of vocal foldsVocal fold elasticity allows folds to “open wider” and “stay apart” longer
|Vocal fold scarParesis/paralysisVocal fold lesions: cysts, nodules, polyps, papillomaVocal fold granulomaSwelling and inflammation (reflux laryngitis, viral laryngitis)
|Unable to project voiceWeak voiceVoice breaks
|Voice Pitch or Highness / Lowness
|Frequency of Sound WavesIncreased tension for high notes (high frequency)Decreased tension for low notes (low frequency)Greater air pressure and increased tension for high notes
|Laryngeal muscles contract to adjust tension of vocal folds–especially for high notesVocal fold elasticity/pliabilityVocal fold edge integrity
|SLN paresis/paralysisVocal fold scarReinke’s edemaVocal fold lesions
|Unable to hit high notesLoss of glissandoVoice breaks
|Voice Quality or Timbre
|Person’s “Own” Voice
Vocal tract resonatorsamplify and modify voiced sound, giving personal quality to a person’s voicee.g., John’s voice not equal to Jim’s voice
|Vocal fold elasticity/pliabilityVocal fold resistanceVocal fold massPerson’s vocal fold features: e.g., stiffness, bulk, sizeVocal tract resonators (throat, oral cavity, nasal cavities)