Vocal Fold Physiology Quiz

Normal Phonation

• Vocal folds (VF) approximate along the entire anterior-posterior dimension during phonation, known as phonatory expiration.

Posterior Glottal Chink

• A subtle posterior opening in the vocal folds is more common in females and is a normal variation, not a pathology. It may manifest as subtle breathiness.

Non-Phonatory Expiration

• Vocal folds are abducted (opened) but not to their extremes during exhalation without voice production.

Forced Inspiration

• Vocal folds are widely abducted during deep inhalation.

Whisper Phonation

• Anterior 2/3 of vocal folds approximate, producing turbulent air flow. Significant posterior glottal chink is present. Not a healthy vocal mechanism.

Intrinsic Laryngeal Muscles

• Six intrinsic muscles control vocal fold position and function: Posterior cricoarytenoid (2), Lateral cricoarytenoids (2), Cricothyroids (2), Transverse arytenoid (1), Oblique arytenoids (2), Thyroarytenoids (2).

Posterior Cricoarytenoids

• Only muscle that abducts (opens) the vocal folds. Rocks arytenoids dorsally. Innervated by the recurrent laryngeal nerve.

Lateral Cricoarytenoids

• Adduct (close) the vocal folds. Innervated by the inferior laryngeal nerve (vagus nerve). Crucial for medial compression.

Cricothyroids

• Stretches and tenses vocal folds, increasing pitch. Innervated by the superior laryngeal nerve.

Transverse Arytenoids

• Adduct vocal folds. A single muscle, not paired, innervated by the recurrent laryngeal nerve.

Oblique Arytenoids

• Adduct vocal folds. Innervated by the recurrent laryngeal nerve.

Thyroarytenoids

• Form bulk of vocal folds. Lower pitch by shortening and thickening the folds. Contains thyromuscularis (lateral) and vocalis (medial) portions.

Dimensions of Sound

• Pitch (frequency), loudness/intensity (amplitude), and quality/timbre (harmonic constitution/waveform) are the three dimensions that describe any simple sound perceptually.

Pitch (Frequency)

• Measured in Hertz (Hz) – cycles per second. Higher frequency = higher pitch; lower frequency = lower pitch. Frequency depends on sound source size, material, shape, and motion.

Octave

• Interval between two notes whose frequency ratio is 2:1.

Intensity/Loudness

• Measured in decibels (dB). Greater energy corresponds to louder sounds.

Quality/Harmonic Constitution/Waveform

• Combination of overtones/harmonics determines the sound quality. A complex tone has a fundamental component (primary frequency) and harmonic components (multiples of the fundamental).

Periodic Sounds

• Harmonics/overtones create a pleasant, less dissonant sound. Produced by continuous, regular patterns of vibration with sufficient mass and elasticity. Vowels predominantly periodic.

Aperiodic Sounds

• No clear harmonic relationships. Characterized by irregular, sudden changes in vibration, potentially resulting from turbulent air flow during consonants.

Myoelastic Aerodynamic Theory

• A comprehensive theory of phonation that considers air pressure, muscle activity, and elasticity of vocal folds (and tissues of the voice mechanism.)

Summary of Vocal Fold Length & Pitch

• Shorter, thicker folds vibrate slower, producing lower pitch. Longer, thinner, more tense folds vibrate faster, producing higher pitch. Higher pitch requires increased sub-glottal pressure and tension.

Laryngeal Function

• Protection of the airway and secondary voice production. Prevents foreign materials from entering the respiratory system, is a valve for air intake, and is a component of forceful exhalation (coughing).

Older Adult Voice Changes

• Muscular atrophy, mucosal thinning/dehydration, loss of ligament elasticity, cartilage calcification, flaccidity, and edema. Sarcopenia (muscle loss) contributes to these changes.

Voice Descriptors: Harsh, Hoarse, Strident, Thin

• Harsh: rough, unmusical voice due to excessive tension.
• Hoarse: breathy and rough
• Strident: tight, hard, pharyngeal tension.
• Thin: tight, hard, oral cavity tension."

Nasality

• Hypernasality: excessive nasality (e.g., cleft palate)
• Hyponasality: reduction in nasality.

Speech Pathology Evaluation

• S/Z ratio: screening tool assessing expiratory control during sustained phonation and phonation-exhalation/control, (comparison of /s/ and /z/ production).
• CAPE-V: standardized clinical evaluation tool for auditory-perceptual voice quality assessment

Vocal Registers

• Glotal, Modal, Midvocal, Falsetto (low to high).

Voice Handicap Index (VHI)

• QoL instrument assessing the functional, physical, and emotional effects of voice disorders.

Perturbation Measures (Jitter & Shimmer)

• Jitter: short-term variability in frequency.
• Shimmer: short-term variability in amplitude.

Functional Voice Disorders

• Result from incorrect use of phonatory system; muscle tension dysphonia (MTD) and psychogenic disorders.

Organic Voice Disorders

• Caused by physiological abnormalities in vocal tract structure or function; e.g., nodules, polyps, cancer, laryngeal nerve injury

Specific Voice Disorders (Examples)

• Vocal Nodules: bilateral, anterior-posterior junctions, misuse;
• Vocal Polyps: unilateral, usually from single events, misuse
• Reinke's Edema: vocal fold thickening due to misuse;
• Contact Ulcers (granulomas): chronic coughing, throat clearing or related to GERD.
• Cancer: tumors in larynx
• Various other factors/diseases which also cause voice disorders

Psychogenic Voice Disorders

• Result from emotional trauma or conflict. Conversion aphonia (complete loss of voice) and other examples.

Specific Psychogenic Voice Disorders

• Aphonia
• Dysphonia
• Functional Dysphonia
• Conversion Aphonia related to inadequate vocal fold adduction.
• Mutational Falsetto (inappropriate high pitch)
• Paradoxical Vocal Fold Movement (PVFM), related to an atypical breathing pattern causing VF adduction during inhalation, prevalent in females.

Additional Notes

• Prevalence of voice disorders may vary based on criteria and diagnosis. Thorough assessment is crucial, often involving collaboration among various healthcare providers.

Test your knowledge on the mechanics of vocal fold function including normal phonation, variations, and intrinsic laryngeal muscles. This quiz covers various concepts related to phonation and respiration techniques involving the vocal folds. Perfect for students in speech and voice disciplines.