5070- Wk 1 Lecture

Introduction to speech science & the nature of sound

How can people communicate without using sound?

Through gestures, facial expressions, sign language, writing, and art.

Why are gestures and facial expressions considered “universals”?

Because they’re widely understood across cultures without needing translation.

What step of communication is affected in aphasia after a stroke?

Converting thoughts into words or deriving meaning from words.

What’s the issue in Childhood Apraxia of Speech (CAS)?

Difficulty accessing sound sequences to produce intelligible words.

What disorder involves difficulty with muscle coordination for articulation?

Dysarthria.

What’s happening when someone hears sound but can’t interpret it?

Receptive aphasia.

What’s the main goal of this course?

To understand sound production, transmission, perception, and how we can measure and visualize it.

Why is learning acoustics important for SLPs and audiologists?

It helps build a scientific foundation to better understand and treat communication disorders.

What does "empirical" mean in science?

Based on data, not opinion.

Why use acoustic measures in speech science?

To reduce listener bias, objectively track progress, and support EBP with measurable data.

Why are hearing, language, and speech interconnected?

Without hearing, there’s no speech. Without language, there’s nothing to say.

What creates sound?

Vibration of a structure (like vocal folds or a guitar string).

What medium does sound typically travel through?

Air. (But also water and solids like metal.)

What is a transverse wave?

A wave where particles move perpendicular to the wave direction (e.g., ripples on water).

What is a longitudinal wave?

A wave where particles move parallel to wave direction (e.g., sound waves in air).

What are compressions and rarefactions?

Compressions = molecules pushed together; Rarefactions = molecules spread apart.

What does a sine wave represent?

The pressure changes of sound over time (idealized pure tone).

What is frequency and how is it measured?

Vibrations per second; measured in Hertz (Hz).

What is the period of a sound wave?

Time per vibration cycle; Period = 1 / Frequency.

What is wavelength?

Distance between repeating peaks; Wavelength = speed of sound / frequency.

What is amplitude?

The size of vibration; correlates with loudness and measured in decibels (dB).

What is wave phase?

Where the wave is in its cycle (measured in degrees).

Can humans perceive phase?

Not directly, but phase difference matters when sounds interact.

Define force.

A push or pull acting on an object (F = ma).

Newton’s Laws

• Inertia

  • Object in motion stays in motion unless acted on.

  • No equation.

• F = ma

  • Force = mass × acceleration.

  • F = force (N), m = mass (kg), a = acceleration (m/s²).

• Action-Reaction

  • For every action, equal and opposite reaction.

Define pressure.

Force per unit area.