Lecture on Motion and Soundwaves

Motion and Sound

Importance of Motion: Understanding motion is crucial because sound itself is a form of movement.
Sound Waves: Sound exists as waves that travel through a medium, and speech is produced through controlled air movement.

Speech Production Process:
- Manage breath and control airflow through vocal folds.
- Build pressure beneath vocal folds to generate sound.
Key Concepts:
- Air pressure drives movement of vocal folds, influencing speed, movement, and velocity.
- Tongue and lips obstruct airflow, aiding sound production.
Interrelated Movements: Different movements in speech production can be interrelated.
Speech Kinematics: Study of movement within the context of speech (similar to physics of sound).

Instruments to Measure Speech Movement:
- Endoscope
- Electromyography (EMG)
- MRI
- X-rays
- Ultrasound
- Electro-glottography (EGG)
Definition of Speed and Velocity in Speech:
- Speed: Distance covered by articulators in a given time.
- Velocity: Speed with direction; if speed changes, it reflects acceleration or deceleration.

Communication Disorders: Examples include cluttering and dysarthria, characterized by altered speed and articulation.
Newton's Laws of Motion in Speech:
- First Law (Inertia): Vocal folds at rest remain so unless acted upon by air pressure.
- Second Law: Acceleration is proportional to the applied force and inversely proportional to mass (heavier folds require more force).
- Third Law: For every action, there is an equal and opposite reaction (force applied equals force exerted back).

Voice Projection: Higher air intake increases subglottal pressure, leading to louder sounds as vocal folds displace more air.
Risk of Vocal Damage: Excessive force from loud speaking or coughing can lead to vocal fold damage.

Work and Power:
- Work: Force applied over distance, resulting in a change of energy.
- Power: Rate of energy expenditure.
Potential and Kinetic Energy: Objects have potential energy when at rest and kinetic energy when in motion.

Properties of Matter:
- Solids: Tightly packed molecules unable to flow.
- Liquids: Can flow and take shape of container.
- Gases: Molecules widely spread, high kinetic energy.
Sound Transmission Medium: Sound travels through solids, liquids, and gases; however, it travels fastest in solids.

Concept of Pressure: Defined as force per area; increases where there are more air particles in motion.
Air Pressure Types:
- Alveolar pressure
- Subglottal pressure
- Supraglottal pressure
- Glottal pressure

Types of Sound Waves:
- Longitudinal Waves: Sound waves traveling in parallel direction to particle movement.
- Transverse Waves: Waves that travel perpendicular to particle movement.
Frequency and Pitch:
- Frequency: Number of cycles per second (measured in Hz).
- Pitch: Perception of frequency; how high or low a sound appears.

Amplitude: Maximum displacement from rest position; relates to loudness of the sound.
Intensity: Power per unit area, diminished with increasing distance.

Definition: Distance traveled in one cycle; influenced by frequency and speed of sound.
Relationship: Higher frequency results in shorter wavelength.

Sound Composition: Most encountered sounds are complex, consisting of multiple frequencies, unlike pure tones that are singular.
Fourier Analysis: Used for decomposing complex sounds into sine waves for analysis.
Fundamental Frequency and Harmonics: Lowest sine wave in the decomposition is the fundamental frequency, contributing to pitch.

Source and Filter Mechanism: Vocal folds produce sound, and the vocal tract shapes and modifies that sound to create distinct speech outputs.