Chapter 1: Introduction to Speech Science and Physical Foundations of Sound

Vocabulary flashcards covering the core acoustic, physiological, and physical concepts of speech science and simple harmonic motion.

Speech Science

The broad study of speech production, the acoustic characteristics of speech, and speech perception.

Perceptual Phonetics

The study of the speech sound characteristics that allow listeners to distinguish sounds, often linked to transcription systems like the International Phonetic Alphabet (IPA).

Physiological Phonetics

The study of the physical structures and their actions during speech production, such as lip closure, tongue placement, and vocal fold vibration.

Acoustic Phonetics

The branch of speech science that applies sound measurement to speech by quantifying vibration frequency, signal intensity, and segment duration.

Medium

A material (such as air, liquid, or solid) through which a wave disturbance travels.

Vibration (Oscillation)

The back-and-forth movement of air particles around their usual equilibrium positions when disturbed by a sound source.

Inertia

The physical tendency of matter to resist a change in its motion, keeping an object at rest or maintaining its movement unless acted on by an external force.

Elasticity

The ability of a disturbed material to return to its original state through a restoring force acting toward the equilibrium position.

Damping

The gradual reduction in the amplitude of a vibration over time as mechanical energy converts to other forms, such as heat.

Simple Harmonic Motion (SHM)

An ideal repeating motion in which the restoring force is directly proportional to displacement and constantly directed back toward equilibrium.

Displacement

The distance and direction that a particle lies from its resting equilibrium position at any given point in time.

Amplitude

The maximum or greatest distance a vibrating particle travels away from its equilibrium position during a cycle.

Velocity

A physical vector quantity that specifies both the speed and the direction of a moving particle.

Acceleration

The rate of change of velocity over time, which reaches its maximum magnitude when an oscillating particle reaches extreme displacement and reverses direction.

Longitudinal Wave

A sound wave in which the individual air particles oscillate parallel to the direction of wave propagation.

Inverse Square Relationship

The principle describing how sound intensity spreads over area in an ideal free field, whereby tripling the distance reduces intensity to $\frac{1}{9}$ of its initial value.

Compression

A phase in a sound wave where neighboring particles are crowded closely together, resulting in relatively high pressure above baseline.

Rarefaction

A phase in a sound wave where neighboring particles are spaced farther apart, resulting in relatively low pressure below baseline.

Atmospheric Pressure

The constant baseline environmental pressure of the medium, identified in the lecture as approximately $14.7\,\text{lb/in}^2$.

Phase

A description of where a repeating cycle or pattern lies at a given instant, measured from $0^\circ$ to $360^\circ$.

Simple Sound Wave (Pure Tone)

A sound wave composed of only a single frequency component, visually represented by the smooth periodic curve of a sine wave.

Complex Sound Wave

An acoustic wave containing multiple frequency components simultaneously, characteristic of human speech sounds.

Superposition

The process by which multiple frequency components combine at each instant to yield a single net particle displacement and pressure variation.

Spectrum

An acoustic display that illustrates the distribution of individual frequency components and their respective strengths in a sound.

Waveform

A visual display plotting signal displacement or amplitude variations horizontally across time.

Frequency

The rate or number of complete vibratory cycles occurring per second, measured in Hertz ($\text{Hz}$) or cycles per second (CPS), with pitch as its perceptual correlate.

Intensity

The degree or amplitude of particle displacement, measured in decibels ($\text{dB}$), with loudness as its psychological correlate.

Period

The duration of time required to complete one full cycle of vibration ($t = \frac{1}{f}$), measured in seconds ($\text{s}$) or milliseconds ($\text{ms}$).

Wavelength ($\lambda$)

The physical distance traveled by a sound wave during one complete cycle, calculated as $\lambda = \frac{1100}{f}$ using the speed of sound ($1100\,\text{ft/s}$).