Lecture 1_Motion_SoundWaves_2025 1.16

CHAPTER 2: DESCRIBING AND EXPLAINING MOTION

Overview of Terminologies, Definitions & Concepts

• Motion: Refers to the change in position of an object over time. It encompasses several key aspects, including:

  • Speed: How fast an object is moving, measured as the distance covered in a specific time frame.

  • Velocity: The speed of an object in a given direction; it's a vector quantity, providing more information than speed alone.

  • Acceleration: The rate of change of velocity over time; it can involve increasing speed (positive acceleration) or decreasing speed (negative acceleration, also known as deceleration).

• Newton’s Laws of Motion: These are three fundamental laws that describe the relationship between the motion of an object and the forces acting on it.

• Energy, Work, Power: Key concepts in physics that relate to motion and forces:

  • Work: Done when a force causes displacement; measured in Joules (J).

  • Power: The rate at which work is performed; measured in Watts (W).

• Properties of Matter: Critical for understanding movement, including:

  • Stiffness: The resistance of an elastic body to deformation.

  • Elasticity: The ability of a material to return to its original shape after deformation.

  • Pressure: The force per unit area exerted by a fluid or gas.

Page 2: Motion and Speech Movements

• Polling Question: Which options represent speech-related movements?

  • Anterior movement of the tongue

  • Pursing the lips

  • Expansion of the lungs

  • Vocal fold adduction

  • Narrowing of the pharynx

  • Raising of the velum

• Study of Speech Movements: Involves examining the management of forces in speech, with these movements assessed in terms of speed, velocity, acceleration, and deceleration, each crucial for clear articulation.

Page 3: Speed, Velocity, Acceleration & Deceleration

• Definitions:

  • Speed: The total distance covered divided by the time taken; for example, the tongue can move at a speed of 1 mm/s.

  • Velocity: This includes both the distance traveled and the direction; an example would be the upward displacement of the jaw at about 1 mm/ms.

  • Uniform Motion: Occurs when an object moves at a constant speed in a straight line without any acceleration.

  • Acceleration: Defines how quickly velocity changes, quantified as meters per second squared (m/s²).

  • Deceleration: This is observed when there is a downturn in velocity over time, essentially negative acceleration.

Page 4: Newton’s Laws of Motion

• Overview: Formulated by Sir Isaac Newton (1642-1727), these three laws laid the groundwork for classical mechanics.

  1. 1st Law (Law of Inertia): A body at rest stays at rest and a body in motion continues in uniform motion unless acted upon by a net external force, which highlights the concept of inertia.

Page 5: Newton’s Second and Third Laws

• 2nd Law of Motion: This law explains that the acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass, summarized by the formula: Force (F) = mass (m) x acceleration (a). The unit of force is Newtons (N), where 1 N is defined as the force that imparts an acceleration of 1 m/s² to a mass of 1 kg.

• 3rd Law of Motion: States that for every action, there is an equal and opposite reaction, reflecting the interactions between pairs of objects and the forces they exert on each other.

Page 6: Application of Newton's Laws in Speech

• 1st Law: Vocal fold motions are influenced by the force exerted by the air that is exhaled through the respiratory system, showing that equilibrium is necessary for stability.

• 2nd Law: Differences in vocal fold characteristics, such as those affected by gender, can change the dynamics of vocal production, especially in conditions like vocal nodules or polyps.

• 3rd Law: The concept of subglottal pressure plays a critical role in the abduction and adduction of the vocal folds, affecting voice pitch and volume.

Work, Power, and Energy

• Work: Defined as the product of force applied over the distance moved in the direction of that force. Measured in Joules (energy change caused by doing work).

• Power: The measure of how quickly work is done; it's calculated as Work/Time and is expressed in Watts (W).

Page 7: Energy Forms

• Potential Energy: This is stored energy, such as that in raised objects or compressed springs, which could be released to do work.

• Kinetic Energy: The energy that an object possesses due to its motion, calculated by the formula KE = 0.5mv², where m is mass and v is velocity.

Properties of Matter: Fluids and Sound Transmission

• Fluid Properties: Both liquids and gases are classified as fluids due to their ability to flow. The speed of sound transmission is contingent upon the medium:

  • Mediums and Sound Speed at 20°C:

    • Air: 343 m/s

    • Alcohol: 1.162 m/s

    • Fresh Water: 1.482 m/s

    • Glass: 5,640 m/s

    • Steel: 5,960 m/s

• States of Matter: Distinct characteristics among solids, liquids, and gases related to molecular arrangements and energy levels.

  • Solids: Have fixed shapes with closely packed molecules.

  • Liquids: Adapt to the shape of their containers, molecules are less tightly packed and can slide past each other.

  • Gases: Have molecules that are far apart, allowing them to expand infinitely to fill any volume.

Pressure and Its Relation to Sound

• Pressure: Defined as the force exerted by air molecules colliding against container walls.

• Pressure Formula: Pressure = Force/Area, measurable in units like Pascals (Pa) and dynes/cm².

• Clinical Reflection: Explore conditions that influence the speed and acceleration of articulatory movements as it relates to speech pathology.

Introduction to Sound Waves and Vibration Types

• Key Concepts:

  • Vibration Types: Include free vibration, where objects oscillate without external interference, and forced vibration, which is induced by external forces.

  • Types of Waves: Longitudinal (sound waves) versus transverse (waves in a medium like water).

  • Sound Propagation: Relates to how sound travels through different states of matter, impacted by particle movement and interactions.

Summary of Sound Production

• Air Particle Behavior: Creates sound through compressions and rarefactions.

• Boundary Behavior of Sound: Explores phenomena such as interference, reflection, refraction, and diffraction, crucial for understanding sound dynamics in various environments.