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SOUND

SOUND. What is sound? Sound is a compressional wave which travels through the air through a series of compressions and rare factions. Materials that are elastic (bend easily) transmit sound better. The speed of sound in air is 347 m/s.

elijah-mccullough
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SOUND

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  1. SOUND

  2. What is sound? • Sound is a compressional wave which travels through the air through a series of compressions and rarefactions.

  3. Materials that are elastic (bend easily) transmit sound better. • The speed of sound in air is 347 m/s. • 2 factors that determine the speed of sound are a) type of medium and b) temperature • 3 things all waves have: amplitude, wavelength, freq • 4 wave characteristics: amplitude, frequency, wavelength, interaction (interference, reflection, refraction, diffraction)

  4. The denser the medium, the faster sound will travel. • The higher the temperature, the faster the particles of the medium will move and the faster the particles will carry the sound

  5. Amplitude • Intensity • Loudness • Height • Energy

  6. Amplitude determines the intensity. • Intensity determines loudness. • Intensity is measured in decibels. • Sound intensities over 120 db are painful.

  7. Sound travels through different media. • We hear sound which usually travels through air. Sound travels through other media as well, such as water and various solids. • Sound travels different speeds in different media. Sound typically travels faster in a solid that a liquid and faster in a liquid than a gas.

  8. Loudness in decibels

  9. How is frequency related to pitch? • The pitch of a sound wave is directly related to frequency. A high-pitched sound has a high frequency (a screaming girl). A low-pitched sound has a low frequency (a fog-horn). • A healthy human ear can hear frequencies in the range of 20 Hz to 20,000 Hz. Humans cannot hear below 20 Hz. Sounds below this frequency are termed infrasonic. • Sounds above 20,000 Hz are termed ultrasonic. Some animals, such as dogs, can hear frequencies in this range in which humans cannot hear.

  10. HUGE: • PITCH is how high or low the sound is. • Sound waves w/ a high frequency have a high pitch. • Sound waves w/ a low frequency have a low pitch. • The human ear can hear in this range: 20-20,000 hz. • Sounds over 20,000 hz are called ULTRASONIC.

  11. Dogs can hear up to 44,000 hz.

  12. Porpoises can hear up to 150,000 hz.

  13. Sideline: Porpoise or dolphin? • Physically, porpoises are smaller than dolphins, reaching up to seven feet long while dolphins reach up to ten.Porpoises have small rounded heads while dolphins have a round bulbous in the head.The dorsal fin of porpoises is different than the dorsal fin of dolphins, having a triangle like fin while dolphin fin is waved.Porpoises live up to mid teens while dolphins reach up to fifty years of life.About behavior, porpoises are shy creatures, very careful of men while dolphins show less fear, approaching more often to boats or nets.

  14. Bats use ultrasonic “sounds” to navigate.

  15. What is the Doppler Effect?The Doppler Effect is the apparent change in frequency detected when the sound is moving relative to the hearer.

  16. More waves/sec = higher pitch and frequency. • A lower frequency produces a sound of lower pitch.

  17. SONAR: SOUND NAVIGATION AND RANGING (Some sources will say SONAR: SOUND NAVIGATION AND RANGING) Sonar is a system that uses the reflection of underwater sound waves to detect objects. This has been used to find sunken ships and schools of fish.

  18. Quality: property of sound that is determined by the blending of its fundamental tone w/ its overtones. • Timbre: sound quality • A fundamental tone= lowest possible freq/pitch • Overtones: sounds of higher frequency produced when sections of strings vibrate.

  19. RESONANCE… • Many objects have a natural frequency – vibrates in a regular pattern. • Resonance occurs when whenever a sound wave has the same frequency as the natural frequency of an object. The sound will cause the object with the same natural frequency to vibrate.

  20. Sound interference: • Sound waves interfere constructively by producing louder sounds. • Sound waves interfere destructively by producing softer sounds.

  21. Acoustics is the study of sound and ways to optimize the hearing of sound inside various structures

  22. Music vs. Noise: • Music: pleasing quality • Noise: unwanted sound • Bad effects of noise? • Increases stress, tension • Increases blood pressure • Headache, pain

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