Sound 2 Overview and Concepts

Sound 2 Agenda

• The agenda for Sound 2 includes four topics
• Describe how moving vibrations form a wave
• How animals use ears to detect sound
• How a microphone converts sound into electrical signals
• How sound is used

Sound 2 Review

• Sound is formed by vibrations of particles traveling through air or other mediums (Vibration)
• Sound waves have crests, troughs, amplitude, and wavelengths
• Compression of a sound wave is when particles are squeezed together
• Wavelength/frequency shows the pitch of a sound
• Amplitude shows how loud a sound is
• Sound waves are longitudinal waves

Sound Vocabulary

• Echo (echoes): Using echoes to find things
• Echolocation: Using echoes to find things
• Sonar: A device that sends sound waves into a medium and records the echoes
• Transducer: A device that converts energy from one form to another
• Reflection of Sound Waves: The bouncing of sound waves off a surface
• Infrasonic sound: Sound below the range of human hearing
• Ultrasonic sound: Sound above the range of human hearing
• Medium: A material through which a sound wave travels (e.g., solid, liquid, gas).
• Radar: A system for locating objects using high-frequency radio waves

How Sound Waves Travel

• Sound waves travel through a medium by vibrating the molecules within the matter.
• High elasticity allows sound to travel faster.
• Elasticity is the ability of a distorted material to return to its original shape when force is removed

Mediums of Sound

• Sound waves cannot travel through a vacuum or outer space

Converting Sound

• A transducer converts energy from one form to another.
• Sound transducers take sound and turn it into electrical energy.
• Microphones and loud speakers are types of transducers

Echoes

• Sound waves can be reflected when they hit a medium
• Echoes are used by animals to help them navigate and understand their surroundings or environment.
• Echolocation is the use of echoes by animals (example-bats).
• Reflected waves are echoes from objects

How We Detect Sound

• Animals (including humans) have complex ears to detect sound.
• Sound waves carry vibrations to the outer ear.
• The ear drum vibrates when sound passes into the ear
• Vibrations continue to ossicles (3 tiny bones in the middle ear) to the inner ear
• The cochlea (fluid within inner ear) stimulates nerve endings
• The nerves signals our brain we hear sounds

Hearing Damage

• Damaging your hearing is very bad since the muscles and bones in your ears do not regenerate
• People can go deaf
• Risks include listening to loud music in earphones
• Risks include improper maintenance and cleaning
• Risks include sound pollution (e.g., airplanes, building construction, traffic).

How Sound is Used

• Invisible waves can be used to detect many things
• Devices like sonar, radar, and ultrasound produce these waves

Sonar (Sound Navigation And Ranging)

• Sonar uses echoes of sound waves to detect objects and measure distances under water
• Sonar uses frequencies inaudible to humans (20,000 - 10,000,000 Hz).
• Animals like dolphins and whales use sonar to hunt and navigate.
• Humans use sonar on boats to find submarines and explore the ocean.

Radar (Radio Detection And Ranging)

• Radar uses echoes of radio waves to detect objects
• Measures objects speed, distance, and location
• Radar uses extremely high frequency waves(3,000,000 - 300 billion Hz)
• Radar detects aircraft, ships, spacecraft, missiles and the weather

Ultrasound

• Ultrasound scans use high-frequency sound waves to create images of a person's body.
• The transducer sends small pulses of high-frequency sound waves into the body to create images
• The echoes can be used to make a picture of what is happening within the body
• Medical treatments use ultrasound waves to do scans

How Animals Use Sound

• Humans can hear 20 - 20000 Hz; other animals hear differently
• Low frequencies are called infrasonic sounds.
• High frequencies are called ultrasonic sounds.

Infrasonic Sound

• Infrasonic sound waves have a frequency less than 20 Hz.
• The human ear cannot hear infrasonic sound waves
• Infrasonic sound travel long distances, helping animals communicate from far away
• Examples: elephants, rhinos, whales, octopus, fish (earthquakes) ,

Ultrasonic Sound

• Ultrasonic sound waves have a frequency above 20000 Hz
• The human ear cannot hear ultrasonic sound waves
• Animals use ultrasonic sound waves to navigate and find food
• Some animals use echolocation
• Humans use ultrasonic waves in medical treatments (scans)
• Examples: bats, dolphins, frogs, mice, moths

How Animals Hear

• Elephants have well developed hearing that can hear through vibrations to their feet
• Elephants use infrasonic sound waves (14/16 - 12,000 Hz) to communicate over long distances
• Bats use echolocation to navigate and find food in the dark
• Bats emit sound waves that bounce off objects
  • They use frequencies from 30,000 - 120,000 Hz
• Dolphins use echolocation to navigate and find food (Sonar)
  • They emit sound and use sonar to listen to the echoes
  • They can also communicate over long distances using ultrasonic sound (75 - 150,000 Hz)

Textbook Practice

• Complete questions 1, 2, 4, 5, 6 from Exploring Science Physics Textbook, pages 62-63

Questions & Answers (from student activities)

• 3 ways to communicate with sound today: Talking, laughing, and shouting
• 3 ways of types of communication made by animal sounds. Warning, dominance, mating calls
• Question: Why is it useful for bats to produce different frequencies of ultrasound?
  • It is useful so that the bats do not get confused while hunting/navigating.
  • Question: Explain two echoes from sonar pulse?
    • Two echoes reflect off separate objects, not equidistant
    • For example, the sea floor and a school of fish.
• Question: How do tiger moths help themselves to survive compared to bats?
  • Tiger moths can confuse bats that use echolocation
• The parts of the ear: eardrum, cochlea, ossicles, ear canal, auditory nerves

Review Quiz

• Animals that use echolocation, bats and dolphins
• An example of a transducer (that is not one) is heat

Additional Review

• SONAR stands for Sound Navigation and Ranging
• Humans can hear between 20 to 20,000 Hz
• Infrasonic sound waves have a frequency less than 20 Hz
• Ultrasonic sound waves have a frequency above 20,000 Hz
• Paper cup telephone uses paper cups, string, and paperclips to communicate through sound

Next Week

• Next week: Lights will be studied
• Bring your Physics textbook next week

This quiz explores the fundamentals of sound, including how vibrations create sound waves, animal hearing, and the functionality of microphones. Additionally, it addresses key vocabulary related to sound such as echolocation and ultrasonic sound. Test your understanding of these essential concepts in sound science.