Voice

Incidence & Prevalence

  • \approx 28\text{ million} U.S. workers report DAILY voice problems
  • 5\%{-}10\% of U.S. workforce = “heavy occupational voice users”
  • Lifetime prevalence of any voice disorder \approx 30\%
  • Source link supplied in lecture: http://www.asha.org/public/speech/disorders/voice/

Societal Impact

  • Lost work-days + treatment for TEACHERS alone ≈ \$2.5\text{ billion} annually

Voice vs. Resonance

  • Voice disorders = abnormal production / absence of
    • Vocal quality
    • Pitch
    • Loudness
    • Resonance
    • Duration (relative to age/sex norms)
  • Voice (phonation)
    • Generated by vocal folds inside larynx → produces a glottal tone
  • Resonance
    • Happens ABOVE the vocal folds (vocal tract shaping, cavities, velum action)
    • Determined by size/shape of head, vocal tract, nasal/oral/pharyngeal cavities

Normal Speech Production Chain

  • Respiration → Phonation → Resonation → Articulation (→ The Voice Foundation)

Respiratory Process (brief refresher)

  • Diaphragm contracts & lowers; rib cage expands
  • Thoracic cavity volume ↑ → Intrapulmonary pressure ↓
  • Air flows DOWN trachea ⟶ lungs
  • Exhalation: alveolar sacs & thorax recoil → air expelled

Helpful Analogies & Media References

  • "Voice is Like a Car" analogy (complex system with parts working together)
  • Lecture points to animation links + anatomical tutorials

Basic Anatomy Map

  • Air-pressure system: lungs, diaphragm, abdominal/chest muscles
  • Vibratory system: vocal folds
  • Resonating/Modifying system: pharynx, oral & nasal cavities, articulators (lips, tongue, soft palate)

The Larynx (Structure & Function)

  • Cartilages, muscles, nerves
  • Primary biological roles
    • Protect lower airway
    • Stabilise thorax for lifting/effort
  • Secondary role: phonation

Laryngeal Cartilages

  • Paired: arytenoids, corniculates, cuneiforms
  • Unpaired: thyroid, cricoid, epiglottis
  • Key landmarks
    • Hyoid bone (suspends larynx)
    • Thyroid notch (Adam’s Apple)
    • Cricothyroid & cricoarytenoid joints (allow rocking/gliding)

Extrinsic Muscles (3 pairs — attach to thyroid oblique line)

  • Thyrohyoid
  • Sternothyroid
  • Inferior constrictor

Intrinsic Muscles & Actions

  • Cricothyroid → lengthen/tense VFs (pitch ↑)
  • Posterior cricoarytenoid → ONLY abductor (opens glottis)
  • Lateral cricoarytenoid → adducts VFs (closes)
  • Transverse arytenoid → adducts arytenoids (VF closure)
  • Oblique arytenoid → narrows laryngeal inlet
  • Vocalis (medial TA) → fine-tunes VF tension
  • Thyroarytenoid overall: sphincter, narrows inlet
  • Innervation
    • All intrinsic muscles by recurrent laryngeal nerve (RLN) of vagus \text{(CN X)}
    • EXCEPTION: cricothyroid by external branch of superior laryngeal nerve (SLN)
    • Bilateral RLN injury → VFs cannot abduct → airway obstruction risk

Endoscopic/Laryngoscopic Views

  • Terms labeled: epiglottis, vallecula, arytenoids, true VFs, esophagus, glottis

Acoustic Concepts

  • Frequency (f): cycles/sec of VF vibration, measured in \text{Hz}
    • Fundamental Frequency F_0 = actual VF vibration rate
  • Pitch: psychological correlate of frequency; influenced by VF tension, mass, and length
  • Intensity (loudness): perceptual correlate of \text{dB} SPL; depends on subglottal pressure & adduction force
  • Quality: subjective judgment; relies on adequate closure, timing, tone of folds

Typical F_0 Ranges & Examples

  • Adult male: 85{-}155\,\text{Hz} (e.g., 130\,\text{Hz})
  • Adult female: 165{-}255\,\text{Hz} (e.g., 250\,\text{Hz})
  • Infant cry: \approx 500\,\text{Hz}

Pitch Modulation Mechanisms

  • Arytenoid cartilages can glide, rock, adduct/abduct → modifies VF length/tension

Physical Principles to Review

  • Boyle’s Law: P1V1 = P2V2 (inverse pressure–volume relationship)
  • Bernoulli Principle: ↑ flow speed → ↓ pressure; explains VF suction during phonation

Descriptive Voice Terms (qualitative)

  • Breathy, harsh/strident, hard-glottal attack, hoarse, strain-strangled, fry, gurgly, dysphonia (impaired), aphonia (no phonation), stridor (noisy inspiration)

Classification of Voice Disorders

  1. Functional – misuse/abuse; no structural change
  2. Neurological – nerve/muscle control issues
  3. Organic – structural/medical pathology

Functional Voice Disorders

Hyperfunctional

  • Excessive laryngeal tension/force

Hypofunctional

  • Inadequate tension or reduced capacity
Laryngitis (acute & chronic >10 days)
  • Inflamed VFs → low pitch, breaks, hoarseness
  • Causes: URI, allergies, vocal overuse, smoking
Vocal Nodules
  • MOST common benign lesions (kids & adults)
  • Typically bilateral at ant.–mid 1/3 of VFs
  • Etiology: chronic abuse (screaming, coughing)
  • Symptom: hoarse voice
Vocal Polyps
  • Benign, usually unilateral, same location as nodules
  • Hoarse quality
Functional Dysphonia/Aphonia
  • Hyper- or hypofunction without organic cause
  • Aphonia often whispered; psychological origin
  • Tx: SLP therapy, counseling
Falsetto (Puberphonia)
  • High, breathy voice via ant. 1/3 VF vibration

Organic Voice Disorders

  • Papillomas (HPV, wart-like, kids 4–6 yr, require surgery)
  • Contact Ulcers (mid-post 1/3 of VFs)
    • Etiologies: hard glottal attack, GERD, intubation
    • Hoarseness; respond to voice therapy & medical mgmt
  • Traumatic injuries (blunt, penetrating, surgical)
  • Laryngeal Cancer (requires medical/surgical; possible laryngectomy)

Neurological Voice Disorders

Hypoadduction

  • VFs cannot fully approximate → paralysis/paresis
    • Unilateral paralysis: breathy, low intensity, diplophonia

Hyperadduction

  • Excessive closure duration/force
    • Spasmodic Dysphonia: strained, strangled; onset ~45 yrs, F>M; Botox + therapy

Review of Etiologies (summary lists)

  • Abuse/misuse: hard attacks, loud singing, tension
  • Irritants: smoke, reflux acid, pollen, cold air, caffeine, alcohol, fumes
  • Neurogenic, psychogenic origins
  • Head/neck trauma, surgical nerve damage
  • Structural pathologies: lesions, scarring, granulomas, Reinke’s edema, webbing, habitual pitch misuse

Resonance & Velopharyngeal (VP) Mechanism

  • Resonance depends on vocal tract volume (length, width, height)
  • VP closure: velum elevates & retracts to posterior pharyngeal wall via
    • Levator veli palatini, musculus uvulae
  • Pharyngeal wall movement
    • Posterior: superior constrictor ± palatopharyngeus (Passavant’s ridge)
    • Lateral: superior constrictor & salpingopharyngeus fold
  • Muscles that LOWER velum
    • Palatoglossus, palatothyroideus, palatopharyngeus

Resonance Etiologies

  • Nasal obstruction (deviated septum, polyps)
  • Hypertrophic tonsils/adenoids
  • Cleft palate or VP dysfunction
  • Neuromuscular weakness (CVA, degenerative)

Resonance Disorders

  • Hypernasality, hyponasality, denasality
  • Cul-de-sac resonance (sound trapped)
  • Nasal emission (audible air escape)

Clinical Assessment

Screening Tasks

  • Count 1{-}10, spontaneous conversation, sustain vowels
  • Goal: decide if full eval needed

Comprehensive Evaluation Components

  • Case history + interview
  • Speech/voice sampling (perceptual & acoustic)
  • Aerodynamic measures
  • Direct visualization (mirror → indirect; endoscopy/stroboscopy → direct)
  • Self-perception scales

Instrumental Tests Mentioned

  • Aerodynamic (airflow/pressure)
  • Electroglottography (EGG)
  • Electromyography (EMG)
  • Photoglottography

Management & Treatment

  • Determined by etiology & diagnosis
  • Multidisciplinary: SLP, ENT/otolaryngologist, surgeons, pharmacology (inc. radiation/chemo)
  • Prosthetics, AAC devices, counseling as needed

Voice Therapy Approaches

  1. Hygienic – teach healthy vocal habits (identify/eliminate misuse)
  2. Symptomatic – target specific symptoms with facilitating techniques (auditory feedback, loudness control)
  3. Psychogenic – address emotional/psychosocial roots
  4. Physiological – directly modify vocal mechanism physiology

Laryngectomy & Alaryngeal Speech

  • Total larynx removal (common cancer tx)
  • Pre-op counseling: establish comm., discuss voicing options
    1. Tracheoesophageal Puncture (TEP) + voice prosthesis (valve shunts pulmonary air into esophagus)
    2. Esophageal speech (air injected, vibrates PE segment)
    3. Electrolarynx (external vibrator)
  • Support networks: WebWhispers, City of Hope, patient testimonials (Mike videos)

Emotional & Social Considerations

  • Voice mirrors personality, emotions, attitudes
  • Conveys semantic content + paralinguistic cues (emotion, personality)
  • Therapy often must address psychosocial impact

Age-Specific Therapy Notes

  • Children: often unaware; therapy may start in kindergarten; parental counseling critical
  • Adolescents: usually motivated; falsetto in boys can have large social penalties
  • Adults: 25\% dislike their voices; holistic therapy considers whole person

Key Concepts to Look Up (explicit lecture prompts)

  • Boyle’s Law (respiratory physics)
  • Bernoulli Principle (aerodynamics of VF vibration)

Resources & Media Links (provided in slides)

  • ENT USA laryngeal videos
  • https://ncvs.org/ (National Center for Voice & Speech)
  • Various YouTube links for TEP demonstrations
  • Support sites for laryngectomees