Speech and Voice Owens 2015

Overview of the Anatomy and Physiology of the Speech Production Mechanism

Understanding Speech Production

• Speech production appears effortless but requires complex coordination of bio-physical events involving numerous muscles and nerves.

• Abnormalities in anatomical structures and physiological systems can interfere with speech production.

• Knowledge of speech mechanism anatomy and physiology is crucial for addressing communication disorders, voice, and swallowing issues, as well as conditions like laryngectomy and cleft palate.

Physiological Subsystems Supporting Speech

Anatomy vs. Physiology

• Anatomy: Study of body structures and their relationships.

• Physiology: Study of the body’s functions and how structures work together.

Speech Production Mechanics

• Speech production is initiated by controlling air pressure and flow from the lungs through the vocal tract.

• Three physiological subsystems involved:

  1. Respiratory System: Provides driving force for speech by generating air pressure.

  2. Vocal Folds: Vibrate to set air molecules in the vocal tract into vibration at multiple frequencies.

  3. Articulatory/Resonating System: Acts as an acoustic filter for sound frequencies.

The Respiratory System

Biological Functions

• Supplies oxygen to blood and removes carbon dioxide, essential for survival.

• Acts as the energy source for sound production.

Structures of the Respiratory System

• Main components:

  1. Pulmonary Apparatus: Lungs, trachea, and pulmonary airways.

  2. Chest Wall: Rib cage, abdominal wall, contents, and diaphragm.

• Lungs: Elastic sacs that expand/contract to facilitate breathing.

Muscles of the Respiratory System

Inspiration

• Diaphragm: Main muscle of inspiration; contracts to enlarge the thorax.

• Other muscles (thoracic and neck muscles) also aid in inhalation.

Expiration

• Function of expelling carbon dioxide and producing speech.

• Expiratory muscles assist in returning the diaphragm to its resting dome shape.

Tidal Breathing vs. Speech Breathing

Tidal Breathing

• Automatic process involving resting breaths, approximately 0.5 L of air per inhalation.

• Involves passive expiration due to gravity and lung recoil.

Speech Breathing

• Rapid, deeper breaths to meet speech demands.

• Involves active muscle contractions to control air pressure and flow.

Lifespan Issues of the Respiratory System

• Breathing rates decrease with age, with significant changes noted from newborn to adult.

• Smoking and health conditions can affect respiratory function, especially in older adults.

The Phonatory System

• Larynx: The main sound generator, prevents foreign objects' entry into the trachea.

• Composed of cartilages, including thyroid cartilage (Adam's apple) and vocal folds.

Vocal Folds

• Paired structures that vibrate to produce sound; they move apart during breathing and together during phonation.

Lifespan Changes in the Laryngeal System

• The larynx gradually grows and descends during development; vocal fold length increases, with different rates between genders post-puberty.

• Aging may lead to ossification and changes in pitch characteristics.

The Articulatory/Resonating System

Structure

• Comprises oral, nasal, and pharyngeal cavities; houses important speech production structures like the tongue, teeth, and velum.

Functions of Major Structures

• Teeth: Aid in both eating and producing certain speech sounds.

• Tongue: Central for shaping sounds; acts as a muscular hydrostat.

• Velum: Critical for speech and swallowing; elevates to separate nasal and oral cavities during speech.

Lifespan Issues of the Articulatory/Resonating System

• Growth patterns of skull and facial bones differ; dentition begins earlier, transitioning through infancy to adulthood.

The Speech Production Process

• Sound production begins with vocal fold vibration.

• Phonation involves open/close cycles of vocal folds triggered by air pressure from the lungs.

• Resultant sound is a complex signal with a fundamental frequency and harmonics.

Summary

• Understanding the anatomy and physiology of speech production is crucial for effective evaluation and treatment of speech disorders for Speech-Language Pathologists.

The anatomy and physiology of speech production involves complex coordination of muscles and nerves, essential for effective communication. Key components include the respiratory system (which generates air pressure), vocal folds (which vibrate to produce sound), and the articulatory/resonating system (which filters sound frequencies). The respiratory system also serves critical biological functions like oxygen supply and carbon dioxide removal. Aging impacts speech mechanisms, such as changes in breathing rates and laryngeal characteristics. Understanding these systems is vital for diagnosing and treating communication disorders.