Module 2 Notes: Voice and Upper Airway Structures ( pp1)

Module 2: Voice and Upper Airway Structures

Objectives

  • Gain a deeper understanding of the voice and upper airway structures.

  • Understand how skeletal structure movement is affected by:

    • Muscle contraction

    • Body positioning

    • Lung pressures

    These factors impact the sound generated at the vocal cord level, leading to voice and upper airway disorders.

Understanding Normal Voice Production

  • Become familiar with different types of normal voices and sound production to identify abnormalities.

  • Listen to various voices and assess pitch, loudness, and quality.

  • Dynamic Perspective:

    • The current approach to normal voicing involves assessing the balance between respiration, phonation, and resonance.

    • The key is to balance these subsystems to create a sound with appropriate pitch, loudness, and quality.

    • Imbalance in one system can lead to adjustments in others and result in a voice disorder.

Example: COPD and Voice

  • Chronic Obstructive Pulmonary Disease (COPD) impairs gas exchange in the lungs, impacting the respiratory system.

  • The patient adjusts the phonatory and resonance systems to compensate for respiratory deficits.

Rapid Movement of Articulatory Structures

  • Video analysis of ultra-rapid MRI during speech and singing demonstrates the rapid movement of articulatory, laryngeal, and resonating cavities.

  • Structures observed in the MRI:

    • Epiglottis

    • Tongue

    • Larynx

    • Posterior pharyngeal wall (Pharynx, Hypopharynx, Oral Pharynx)

    • Hard palate

    • Velum/Soft palate, Uvula

    • Nasal cavity

    • Vertebra of the spinal column (Cervical, Thoracic)

    • Spinal cord and brain stem

Observations from the MRI Video

  • Rapid tongue movement during speech

  • The velum adjusts rapidly to block off or open the nasal passages for different sounds.

  • The larynx moves and vibrates more during singing compared to speaking, indicating the athletic use of vocal cords.

  • When singing there is a continuous stream of air that is being shaped.

  • When speaking, breaths are taken more often.

  • Larynx Tilting: Tilting occurs through activation of pitch-changing muscles that elongate and shorten the vocal cords.

Clinical Application of Voice Subsystems

  • Clinicians need to determine where the breakdown occurs within the subsystems (respiration, phonation, resonance).

  • This model is used for practical clinical application in diagnosing voice disorders.

Aerodigestive Disorders and Scope of Practice

  • Over the past 10-15 years, the field of voice disorders has expanded to include aerodigestive disorders.

  • Aerodigestive tract: Involves the respiratory tract and the upper part of the swallowing/ digestive tract, serving feeding, swallowing, and voice functions.

  • Voice clinicians need to be knowledgeable about aerodigestive disorders because they can cause voice disorders.

  • ASHA includes the aerodigestive tract as part of the scope of practice.

  • The scope of practice includes the pharynx and larynx, which act as a gate over the trachea (lower airway).

  • The pulmonary tract is a concern as it affects the larynx/voicing and swallowing.

  • Upper digestive tract: The esophagus, located behind the larynx, can contribute to irritation in the laryngeal area.

Anatomical Considerations

  • Location of structures like small intestines, ascending/transverse/descending colon, and stomach.

  • The diaphragm extends high up, with the esophagus passing through it into the stomach.

  • The liver, pancreas, gallbladder, and spleen can affect the esophagus.

Breathing and Swallowing Mechanisms

  • Breathing involves using the larynx to vibrate a column of air. Swallowing employs the same structures.

  • During swallowing: The epiglottis closes off the airway, the vocal cords close, and the upper esophageal sphincter relaxes, allowing food/liquid to enter the esophagus.

Resonance

  • Resonance determines the unique characteristics of a voice.

  • The shape, density, and size of resonating structures influence the sound.

  • Singers manipulate these aspects.

  • The ventricular space is located just above the vocal folds.

  • Ventricular folds consist of mucosal tissue epithelium.

  • Aryepiglottic folds attach to the Epiglottis.

  • Hypopharynx comprises pharyngeal constrictor muscles, crucial for shaping the upper vocal tract.

Pharyngeal Structures and Vocal Tract

  • Identify the structures:

    • Hypopharynx

    • Oropharynx (behind the oral cavity)

    • Nasopharynx

  • These structures are dynamic during speech, as seen in MRI.

  • The vocal tract's interruptions or contractions can vary in strength.

Vocal Tract Manipulation and Resonance

  • Changing the shape of the vocal tract can filter sound and alter the fundamental frequency.

  • Experiment:

    • Produce an "oh" sound and tighten the back of the throat (pharynx).

    • Direct the "oh" sound into the back of the nose to make it sound more nasally.

    • Palpate the larynx while moving the sound from nasal to low in the throat.

Resonance and Voiceless Phonemes

  • Resonance occurs even on voiceless phonemes, shaping the sounds (e.g., differentiating between /p/, /t/, /k/).

  • Resonance is a dynamic process of shaping the tone created at the larynx into a complex sound for expressing emotion and linguistic information.

Skeletal Structures and Resonance

  • Skeletal structure disorders (e.g., growths in the sphenoid, frontal, ethmoid area) can impact resonance and voice quality.

  • Facial bones and the pharyngeal cavity affect resonance.

Forces Involved in Laryngeal and Resonating Processes

  • Passive forces: Natural recoil of muscles and cartilages, surface tension, gravity, and aeromechanical forces.

  • Volitional control: Muscles of the pharynx, velum, and outer nose.

Neural Substrates

  • Neural substrates of the pharynx, velum and outer nose: cranial nerves involved

  • Velopharyngeal Closure: more to come.

  • Etiologies: To be discussed on Wednesday.

Normal Laryngeal Function

  • The epiglottis, aryepiglottic folds, false vocal cords and true vocal cords make uo the laryngeal structure.

  • True vocal cords are muscular and attach to the arytenoid (cartilaginous portion) in the posterior aspect.