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Sound and Intensity

Sound and Intensity. The speed of sound in various media. Waves travel more rapidly in solids and in hotter gases. Observe the chart. Range of Hearing. Observe the range of hearing in your text book MHR pg. 373 A dog can hear a frequency of 15 Hz to 50000 Hz

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Sound and Intensity

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  1. Sound and Intensity

  2. The speed of sound in various media • Waves travel more rapidly in solids and in hotter gases. • Observe the chart

  3. Range of Hearing • Observe the range of hearing in your text book MHR pg. 373 • A dog can hear a frequency of 15 Hz to 50000 Hz • Human can hear a frequency of 20 Hz to 20,000 Hz • Take a look at the moth and bat…

  4. Now lets listen to the different frequencies… • Hit it DJ

  5. Sound Intensity • The amount of sound energy being transferred over a certain area • We do not use sound intensity, but rather decibels

  6. Decibel ( dB) • Measurement of sound intensity • You have to use logarithms to calculate dB • I will show you charts so you can compare dB • Please note the following: • Decibel: • A decibel (dB) is a measure of sound intensity. The dB scale is logarithmic, meaning that a change of 10 dB represents a tenfold change in loudness. So, a sound measuring 30 dB is 10 times louder than a sound measuring 20 dB.

  7. Decibel Scale

  8. Let’s Summarize • Audible sound waves range from 20 Hz to 20 kHz • Infrasonic waves have frequencies below 20 Hz • Ultrasonic waves have frequencies above 20,000 Hz • Loudness is described in decibels rather that sound intensity

  9. What are infrasonic waves? • Infrasonic frequencies are felt as vibrations which, if intense enough, may result in feelings of nausea, vertigo and eventual black-out or internal hemorrhaging.

  10. What about ultrasonic waves? • “As ultrasonic waves tend to have very high frequencies, it follows that they also have very short wavelengths. As a result, ultrasonic waves can be focused in narrow, straight beams.” • Yeah, so how is that an application???

  11. “Ultrasound has been used to bind, or coagulate, solid or liquid particles that are present in dust, mist, or smoke into larger clumps • This is know as ultrasonic scrubbing, by which particulate matter is coagulated in smokestacks before it pollutes the atmosphere. Coagulation has also been used at airports to dispersefogand mist.”

  12. Lab time: Investigating Vibrations What… I did not sign up for this!!!! Relax, this is a fun lab Now get up, stretch and lets do some lab work 

  13. The Pendulum Experiment • A handout will be given to you for this lab. • 

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