C

Transfer of Sound Energy Through Vibrations

Introduction to Sound

  • "In space, no one can hear you scream." - Johan Harstad

16.1 What Causes Sound?

  • Vocabulary:

    • Vacuum: A space entirely devoid of matter (no solids, liquids, or gases).

    • Vibrations: Continuous and rapid movements to and fro or forwards and backwards.

    • Collide: To hit with force while moving.

Bell in a Vacuum

  • Vacuum Pump: Demonstrates sound transmission.

How Does Sound Travel?

  • Sound travels in waves.

  • A wave is a disturbance that moves and transports energy through a medium (e.g., air particles).

  • Speaker: Creates a disturbance that initiates sound waves.

Properties of States of Matter

  • Solid: Cannot be squashed.

  • Liquid: Cannot be squashed.

  • Gas: Can be squashed.

Disturbance and Sound Transmission

  • In sound, the disturbance is a vibrating object.

  • Sound can travel through gases, liquids, and solids.

Sound Travel in Different Media

  • The medium's composition affects sound speed:

    • Sound travels slowest in gases, faster in liquids, and fastest in solids.

    • A medium is essential; without it, sound cannot travel.

Testing Your Understanding

  • Sound Wave Transmission:

    1. Without a medium, sound cannot collide or travel.

    2. Solid: Fastest due to molecules being closely packed.

    3. Liquid: Fast due to close molecular packing.

    4. Gas: Slow due to distant molecules.

Sound Traveling Scenarios

  • Predict sound travel times to Fred the Frog on land vs. in the sea vs. in space.

  • Where does sound travel fastest? In solid media.

The Speed of Sound

  • The speed of sound depends on the medium:

    • Faster in denser mediums

    • Temperature affects speed: sound travels differently on cold and warm days.

Activities Involving Sound

  • Can Sound Move Objects?: Investigating how vibrations move materials (e.g., sprinkles dancing).

  • Discussion of how sound impacts vibrations in various setups.

Anatomy of Hearing

16.2 How We Hear Sound

  • Hearing Process:

    1. Sound waves enter the outer ear and travel through the ear canal to the eardrum.

    2. The eardrum vibrates, conveying vibrations to ossicles (tiny bones).

    3. Bones amplify vibrations, transferring them to the cochlea in the inner ear.

    4. Hair cells in the cochlea send signals through the auditory nerve to the brain.

Ear Anatomy

  • Outer Ear: Pinna, collects sounds.

  • Middle Ear: Contains ossicles (Hammer, Anvil, Stirrup).

  • Inner Ear: Cochlea, processes sound into nerve signals.

Mechanics of Hearing

  • Ears not only detect sound but help in balance via semi-circular canals and Eustachian tube for pressure equalization.

How Sound Varies

16.3 Sound Characteristics

  • Vocabulary:

    • Vary: Difference in characteristics.

    • Pitch: Quality determined by vibration rates.

    • Loudness: Perceived intensity of sound.

    • Frequency: Rate of occurrence of sound waves.

Amplitude and Frequency

  • Amplitude: Maximum extent of vibration, correlating to loudness.

  • Frequency: Measured in Hertz (Hz), correlating to pitch.

  • Healthy hearing range: 20-20,000 Hz.

Intensity of Sound

  • Measured in decibels (dB).

  • Zero dB: Barely audible; 120 dB: Very loud/painful.

Frequency and Loudness Relationship

  • Amplitude leads to intensity; frequency influences pitch.

Application of Sound Science in Society

16.4 Societal Implications of Noise

  • Vocabulary:

    • Isolated, sirens, reflected, pulse.

Uses of Sound

  • Applications include SONAR and ultrasound:

    • SONAR sends out pulses to measure distance.

    • Ultrasound utilizes high-frequency sound pulses for imaging.

Noise Pollution

  • Definition: Collection of unpleasant sounds.

  • Excessive noise: Above acceptable levels causing health issues.

    • Recommendations: Keep noise below 50 dB for concentration.

    • Protection strategies: Earplugs, headphones, avoiding loud environments.