Voice Study Notes

SPEECH PRODUCTION: Four Parameters

• Speech production involves the coordinated effort of four main systems:

  • Respiration: Provides the airstream from the lungs.

  • Phonation: Affects vocal folds in the larynx to produce voiced or voiceless sounds.

  • Resonance: Modifies sound in the pharynx, oral, and nasal cavities.

  • Articulation: Shapes sounds into phonemes using articulators.

1. Respiration

• Air from the lungs is expelled through the trachea, passes through the larynx, and exits from the mouth/nose.

• An adequate airstream is essential for speech production.

• Potential Problem: Insufficient lung support or poor respiratory control can lead to an inability to cause vocal folds to vibrate effectively or to sustain speech, resulting in soft or short utterances.

2. Phonation (Larynx)

• Larynx Framework: Situated between the trachea and the hyoid bone, containing the vocal folds.

  • Functions: Controls airflow, generates sound, manages $CO<em>2$ and $O</em>2$ exchange, and protects the lungs from foreign objects.

  • Structure: Includes the hyoid bone, thyroid cartilage, cricoid cartilage, and tracheal ring.

• Main Cartilages of Larynx and Their Functions/Location:

  • Thyroid Cartilage: Largest cartilage (Adam's apple). Involves superior/inferior horns. Located superior to the cricoid cartilage.

  • Cricoid Cartilage: Shaped like a signet ring, forming the base of the larynx. Important for laryngeal support and serves as the posterior attachment for the arytenoid cartilages. Located inferior to the thyroid cartilage.

  • Arytenoid Cartilage: Paired cartilages sitting atop the posterior cricoid cartilage, crucial for vocal fold movement (abduction/adduction). Their movements open (abduction) and close (adduction) the vocal folds. Their rocking and gliding motions shorten or lengthen the vocal folds in conjunction with cricoid and thyroid movements.

  • Epiglottis: A leaf-shaped cartilage located at the top of the larynx, behind the hyoid bone, preventing food/liquid from entering the trachea during swallowing.

• Vocal Folds:

  • Composed of ligaments, tendons, muscles, and mucous membranes.

  • Movement:

    • Abduction: Vocal folds are apart for breathing (air flow).

    • Adduction: Vocal folds are together, blocking airflow (holding breath) or vibrating for voiced sounds.

  • Vibration: Creates a "buzzing" sound for voiced phonemes (e.g., /b/, /d/, /z/, /o/). Non-vibrating folds produce just "noise" for voiceless sounds (e.g., /t/, /s/) as air flows between them without vibration.

  • Glottis: The space between the vocal folds.

• Pitch and Frequency:

  • Frequency: Actual rate of vocal fold vibration, measured in Hertz (Hz).

    • Males: approximately $125$ Hz.

    • Females: approximately $215$ Hz.

  • Pitch: Perceived frequency (low, medium, high).

  • Factors Affecting Fundamental Frequency (Pitch Changes):

    • Length: Longer vocal folds yield lower frequency; shorter produce higher frequency. Cricoid and thyroid cartilages can rock and glide, lengthening (increasing tension, raising pitch) or shortening (decreasing tension, lowering pitch) the vocal folds.

    • Mass: Increased mass lowers frequency; less mass raises it.

    • Tension: Increased tension (vocal folds stretched) leads to higher frequency; decreased tension lowers it.

• Loudness and Intensity:

  • Intensity: Physical sound pressure, measured in decibels (dB).

    • Examples: Whisper ($\approx 30$ dB), conversational speech ($\approx 60$ dB), plane takeoff ($\approx 140$ dB).

  • Loudness: Perceptual correlate of intensity (soft, medium, loud).

  • Changing Intensity (Loudness Changes): Increased air pressure from the lungs and increased vocal fold separation followed by forceful closure increases the amplitude of vibration, leading to higher intensity.

• Cranial Nerve X (Vagus Nerve): Innervates the pharynx, larynx, and soft palate, making it critical for voice production and control of vocal fold movement and tension.

3. Resonance & Articulation (Vocal Tract / Supralaryngeal System)

• After passing through the larynx, the air is manipulated in the supralaryngeal system, which is the vocal tract.

• Vocal Tract Four Parts (PhonART):

  • Pharynx: Connects the respiratory and digestive systems; divided into three sections:

    • Nasopharynx: Uppermost part, posterior to the nasal cavity.

    • Oropharynx: Middle part, posterior to the oral cavity.

    • Laryngopharynx: Lowermost part, superior to the larynx and esophagus.

  • Oral Cavity: Begins at the mouth, crucial for non-nasal sound production.

  • Nasal Cavity: Plays a role in producing nasal sounds.

  • Articulators: Structure within the vocal tract that shape the sound.

• Velopharyngeal Port & Closure:

  • The velopharyngeal port functions as a valve between the oral and nasal cavities.

  • Important: It should be open only for nasal phonemes (e.g., /m/, /n/, /ŋ/) and closed for all other speech sounds (non-nasal phonemes) to direct airflow through the oral cavity.

  • Informal measurements for Velopharyngeal Port working: Pinching the nose to see if nasal sounds can be produced (they shouldn't be), listening for nasal emission on non-nasal sounds, a "mirror fogging" test under the nose during speech.

  • Formal measurements: Nasometry (measures nasal vs. oral acoustic energy), aerodynamic instruments (measures nasal airflow), nasoendoscopy (visualizes velopharyngeal closure).

• Shaping Sound into Phonemes: The "buzzing" sound (from voiced phonemes) or just "noise" (from voiceless phonemes) produced in the larynx is modified and shaped by the articulators and resonance characteristics of the pharynx, oral, and nasal cavities to create distinct speech sounds (phonemes).

• Overall Phoneme Production: Speech sounds are produced by the airstream from the lungs (respiration) causing or not causing vocal fold vibration in the larynx (phonation), which is then resonated in the vocal tract (resonance) and shaped by articulators (articulation) into specific phonemes.

• Potential Problem: If there's insufficient velopharyngeal closure for non-nasal sounds, hypernasality will occur, making speech sound excessively nasalized. If the port is overly closed for nasal sounds, hyponasality results.

Important Terms

• Anterior: Towards the front.

• Posterior: Towards the back.

• Superior: Towards the top.

• Inferior: Towards the bottom.

• Medial: Towards the middle.

• Lateral: Towards the side.

• Abduction: Vocal folds Apart for airflow (breathing).

• Adduction: Vocal folds Together blocking airflow (holding breath).

Voice Disorders

• Definition: Significant differences in pitch, loudness, resonance, or phonatory quality relative to individuals of similar age, gender, culture, and other demographics.

I. Pitch and Frequency

• Pitch: Perceived frequency, which can be low, medium, or high.

• Habitual Pitch: The typical speaking pitch a person uses.

• Abnormal Pitch: Can be caused by:

  • Puberphonia (Mutational Falsetto): Abnormally high pitch maintained by males during puberty.

  • Glottal Fry: Low pitch due to tightly approximated, slack vocal folds vibrating in a low-frequency, irregular pattern.

II. Loudness and Intensity

• Loudness: Perceptual correlate of intensity (soft, medium, loud).

• Disorders:

  • Monotone: Loudness does not vary.

  • Overloudness: Shouting or loud talking, often resulting from vocal abuse.

  • Underloudness: Lack of respiratory support, vocal fold paralysis (e.g., Vagus nerve lesion), or conditions like Parkinson's disease or ALS where vocal folds may not abduct sufficiently for strong air pressure, leading to vocal strain and reduced loudness.

III. Resonance

• Characteristics: Resonation gives richness (timbre) to the voice via air vibration in the vocal tract. Physical measures include nasal versus oral airflow.

• Perceptual Correlates:

  • Hypernasal: Excessive nasal resonance due to the velopharyngeal port remaining open during non-nasal production.

  • Hyponasal: Insufficient nasal resonance due to the velopharyngeal port closing during nasal sound production or nasal obstructions.

• Causes of Resonance Issues: Anatomical problems (e.g., cleft palate, which prevents proper velopharyngeal closure), neurophysiological disorders affecting velopharyngeal function, allergies causing nasal blockage.

IV. Phonatory Quality

• Definition: Quality of voice created through vocal fold activity during vibration. Perceptual descriptions include breathy, hoarse, strained, etc.

• Physical Characterizations of Common Voice Issues:

  • Hard Glottal Attack: Abrupt start of voice due to forceful vocal fold adduction.

  • Glottal Fry: Low pitch, rough sound produced with tightly approximated vocal folds.

  • Breathy Phonation: Vocal folds do not close completely, allowing air to escape during phonation. Can be due to Vagus nerve damage (paralysis) or other issues preventing full adduction.

  • Spasticity (Strained/Strangled): Excessive vocal tension, leading to effortful production and a tense, strangled quality.

  • Hoarseness: Distortion of pitch with loss of higher frequencies, often due to irregular vocal fold vibration (e.g., from nodules).

  • Dysphonia: General term for a disordered or abnormal voice.

  • Aphonia: Total lack of voice.

  • Diplophonia: Occurs when vocal folds produce two pitches simultaneously, indicative of vocal fold pathology or paralysis affecting vibration.

  • Hypofunction: Underfunctioning vocal folds leading to inadequate closure (e.g., breathy voice).

  • Hyperfunction: Overfunctioning vocal folds creating excess tension (e.g., strained voice).

• Physical Correlates: For Resonance and Phonatory Quality, the physical correlate is often the acoustic “waveform” of the perceptual factors, including objective measures like jitter (cycle-to-cycle frequency perturbation), shimmer (cycle-to-cycle amplitude perturbation), and sound-to-noise ratio.

Assessment of Voice Parameters (Perceptual and Physical)

• Perceptual Assessment: Subjective judgment by listening and evaluating voice quality (pitch, loudness, quality, resonance) based on the clinician's ear.

• Physical/Instrumental Assessment:

  • Loudness: Sound level meter (measures decibels).

  • Pitch/Frequency: Praat software (analyzes fundamental frequency).

  • Quality: Praat software (measures jitter/shimmer), s/z ratio ($1.0$ (ideal), >1.4 (problem indicates breath support or glottal closure issues)).

  • Resonance: Nasalance with nasometer (measures percentage of nasal energy).

Alaryngeal Communication

• Situations: Occurs when an individual cannot use vocal cords, typically due to:

  • Laryngectomy: Surgical removal of the larynx, often due to cancer.

  • Tracheostomy: A surgical opening in the trachea to insert a tube for breathing, bypassing the larynx.

• Methods for Replacing Speech:

  • Passy-Muir Valve: A one-way valve attached to a tracheostomy tube, allowing air to pass over the vocal folds for speech during exhalation.

  • Electrolarynx: A battery-operated device held to the neck, which generates a vibratory sound that is then articulated into speech.

  • Esophageal Speech: Air is compressed in the esophagus and expelled, causing the pharyngoesophageal (PE) segment to vibrate, generating a sound for speech.

  • Tracheoesophageal Puncture (TEP): A surgical creation of a small opening between the trachea and esophagus, often with a one-way valve (voice prosthesis), to allow pulmonary air to vibrate the PE segment for improved esophageal speech.

  • Whispering: Though not true alaryngeal communication, it involves shaping exhaled air without vocal fold vibration, often used when phonation is impaired.

Prevalence and Risk Factors for Voice Disorders

• Voice disorders generally occur more frequently than other communication disorders, and are more common in women than men.

• Warning Signs/Risk Factors:

  • Vocal abuse (e.g., yelling, frequent throat clearing, speaking in noisy environments).

  • Professional voice use (singers, teachers, public speakers).

  • Gastroesophageal Reflux Disease (GERD) or allergies (irritation to vocal folds).

  • Reports of losing voice or requiring excessive effort to speak.

  • Changes in voice qualities (resonance, pitch, loudness) persisting for more than two weeks.

  • Mental health impacts (stress, anxiety, depression).

Classification of Voice Disorders into Three Main Categories

1. Vocal Abuse

• Definition: Chronic misuse or overuse of the vocal mechanism.

• Perceptual Observations: Often leads to breathy, low-pitched, and hoarse voices.

• Specific Conditions:

  • Vocal Nodules: Bilateral bumps at the midline of the vocal folds, initially acute (bruises) and later fibrous. Result from hard vocal fold contact.

  • Contact Ulcers & Granulomas: Inflamed lesions on the arytenoid cartilages due to forceful vocal fold contact, often exacerbated by GERD.

• Etiologies: Professional voice users, GERD, allergies, yelling, frequent throat clearing, speaking in noisy environments, caffeine, smoking.

2. Neurogenic Disorders

• Result from neurological damage affecting voice production, impacting the central and peripheral nervous systems, particularly the Vagus nerve.

• Specific Conditions:

  • Vagus Nerve Lesions: Can cause vocal fold paralysis (unilateral or bilateral, adduction or abduction paralysis), leading to a breathy voice or difficulty breathing.

  • Spasmodic Dysphonia: Intermittent voice stoppages due to involuntary laryngeal spasms.

    • If spasm causes abduction, the voice is generally breathy.

    • If the spasm causes closure (adductor spasmodic dysphonia), the voice is often strained, strangled, or grunting.

  • Amyotrophic Lateral Sclerosis (ALS): Progressive muscle weakness affecting the voice, leading to breathy, low-pitched, low-loudness, and hypernasal speech.

  • Parkinson's Disease: Impacts voice dynamics due to dopamine deficits and weakened respiratory systems, resulting in decreased loudness and a breathy quality.

  • Iatrogenic Etiology: Voice disorders resulting from medical treatments (e.g., surgery causing nerve damage), with perceptual characteristics dependent on the specific damage.

  • Tourette's Syndrome: Voice-related tics such as clicks, snorts, squeaks.

  • Paradoxical Vocal Fold Movement (PVFM): Inappropriate adduction of vocal folds during inhalation, leading to complaints of breathing difficulty, choking, wheezing, or stridor.

3. Psychogenic Disorders

• Disorders rooted in emotional/psychological factors, exhibiting physical symptoms without voluntary control.

• Specific Conditions:

  • Conversion Disorder: Physical symptoms (like aphonia or dysphonia) without a physical cause, resulting from psychological stress.

  • Puberphonia/Mutational Falsetto/Functional Falsetto/Juvenile Voice Disorder: High-pitched voice maintained by males after puberty despite normal laryngeal development.

Treatment for Voice Disorders

• Goals: Eliminate underlying causes (etiology), prevent reoccurrence, and improve or compensate for voice problems.

• Medical Interventions:

  • Medication: For underlying conditions (e.g., anti-reflux medication for GERD).

  • Botox Injections: For spasmodic dysphonia to temporarily paralyze spastic muscles.

  • Psychological Referral: For psychogenic disorders.

  • Surgery (Phonosurgery): To remove vocal nodules, lesions, or to bulk up vocal folds for better contact in cases of paralysis.

  • Palatal Lift: A prosthetic device for hypernasality caused by velopharyngeal insufficiency.

• Behavioral Approaches:

  • Counseling & Vocal Hygiene Education: Identification and modification of vocal abuse behaviors, proper hydration.

  • Laryngeal Massage: To reduce laryngeal muscle tension.

  • Vocal Function Exercises (VFE): A series of structured exercises to improve vocal fold strength, flexibility, and coordination.

  • LSVT (Lee Silverman Voice Treatment): High-effort, intensive treatment for hypokinetic dysarthria (e.g., in Parkinson's) focusing on increasing vocal loudness.

  • Biofeedback: Using instrumental feedback (e.g., pitch monitors) to help clients modify vocal parameters.

  • Yawning/Sniffing/Open Throat Techniques: For paradoxical vocal fold movement to encourage vocal fold abduction.

Comprehensive Assessment

• Beyond regular components (e.g., I QUOTE CHIN NO CRI DS for case history, oral motor exam, swallowing screening), a voice assessment includes specific evaluations of voice parameters using perceptual and instrumental tools.

1. Respiration

• Perceptual: Observing ability to produce long sentences without breath support issues, assessing maximum phonation time ("ah" for $20-25$ seconds in adults).

2. Phonation (Loudness, Pitch, Quality)

• Loudness:

  • Perceptual: Assessing loudness and its variability during counting or conversational speech.

  • Instrumental: Praat software (measures decibels), sound level meter.

• Pitch:

  • Perceptual: Assessing pitch and its variability (typical range for speech is $2-3$ octaves), identifying optimal pitch.

  • Instrumental: Praat software (measures fundamental frequency).

• Quality:

  • Perceptual: Listening for breathy, hoarse, strained, or other abnormal qualities.

  • Instrumental: S/z ratio ($1.0$ ideal; >1.4 indicates potential glottal closure or respiratory issues). DDK (diadochokinetic) rates ("puh-tuh-kuh") indirectly assess laryngeal valving. Praat software (measures jitter/shimmer for vocal fold irregularity, sound-to-noise ratio). Electroglottography (EGG) infers vocal fold opening and closing patterns. Laryngoscopy/Endoscopy visually views vocal folds.

3. Resonance (Hyper/Hyponasality)

• Perceptual:

  • Listening for hypernasality or hyponasality.

  • "Paper paddle" or mirror test under the nose during speech to detect nasal air emission.

  • Sentences containing oral sounds (e.g., "Buy baby a puppy") and nasal sounds (e.g., "My mother makes me mad," "Maybe baby") to assess velopharyngeal function.

  • CAPE-V (Consensus Auditory-Perceptual Evaluation of Voice) for structured perceptual analysis.

• Instrumental: Laryngoscopy/Endoscopy to visually view velopharyngeal closure and nasal blockages. Aerodynamic measurements for nasal airflow.

4. Articulation

• Assessment: Part of the comprehensive oral-motor examination, evaluating strength, range of motion, symmetry, and coordination of articulators (lips, tongue, teeth, hard palate, soft palate, alveolar ridge) to ensure proper structure and function for speech sound production.