sound 13 3
Download
Skip this Video
Download Presentation
Sound 13-3

Loading in 2 Seconds...

play fullscreen
1 / 15

Sound 13-3 - PowerPoint PPT Presentation


  • 151 Views
  • Uploaded on

Sound 13-3. A “physical phenomenon that stimulates the sense of hearing.”. What do you think? . A violin, a trumpet, and a clarinet all play the same note, a concert A. However, they all sound different. What is the same about the sound? Are the frequencies produced the same?

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Sound 13-3' - ganit


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
sound 13 3

Sound13-3

A “physical phenomenon that stimulates the

sense of hearing.”

what do you think
What do you think?
  • A violin, a trumpet, and a clarinet all play the same note, a concert A. However, they all sound different.
    • What is the same about the sound?
      • Are the frequencies produced the same?
      • Are the wave patterns the same?
    • Why do the instruments sound different?
standing waves
Standing Waves
  • Standing waves are produced when two identical waves travel in opposite directions and interfere.
    • Interference alternates between constructive and destructive.
  • Nodes are points where interference is always destructive.
  • Antinodes are points between the nodes with maximum displacement.
standing waves on a string
Standing Waves on a String
  • There is a node at each end because the string is fixed at the ends.
  • The diagram shows three possible standing wave patterns.
  • Standing waves are produced by interference as waves travel in opposite directions after plucking or bowing the string.
  • The lowest frequency (one loop) is called the fundamental frequency (f1).
standing waves on a string1
Standing Waves on a String
  • To the left is a snapshot of a single loop standing wave on a string of length, L.
  • What is the wavelength for this wave?
    • Answer:  = 2L
  • What is the frequency?
    • Answer:
harmonics
Harmonics
  • n is the number of loops or harmonic number.
  • v is the speed of the wave on the string.
    • Depends on tension and density of the string
  • L is the length of the vibrating portion of the string.
  • How could you change the frequency (pitch) of a string?
fundamental frequency
Fundamental Frequency

Click below to watch the Visual Concept.

Visual Concept

standing waves in an air column
Standing Waves in an Air Column
  • Wind instruments also use standing waves.
    • Flutes, trumpets, pipe organs, trombones, etc.
  • Some instruments have pipes open at both ends while others have one end closed.
    • Air is free to move at open ends so antinodes occur.
    • Closed ends are nodes.
  • The velocity of the wave is now the velocity of sound in air (346 m/s at 25°C).
wind instruments
Wind Instruments
  • Wind instruments are not as simple as organ pipes.
    • The shape is not always cylindrical.
    • The holes change the wave patterns as well.
    • The size of the “pipe” varies along the length.
p ractice problems
Practice Problems
  • One string on a toy guitar is 34.5 cm long.
    • What is the wavelength of the first harmonic or the fundamental wavelength?
      • Answer: 69.0 cm or 0.690 m
    • The string is plucked and the speed of the waves on the string is 410 m/s. What are the frequencies of the first three harmonics?
      • 590 Hz, 1200 Hz, 1800 Hz
      • Note: The use of significant figures causes the multiples of 590 to be 1200 and 1800 because only two significant figures are present in the answer.
p ractice problems1
Practice Problems
  • An organ pipe open at both ends is 34.5 cm long.
    • What is the wavelength of the first harmonic or the fundamental wavelength?
      • Answer: 69.0 cm or 0.690 m
    • What are the frequencies of the first three harmonics if the air temperature is 25.0°C?
      • Answers: 501 Hz, 1000 Hz, 1500 Hz
    • Answer the same questions if the pipe is closed at one end.
      • Answers: 251 Hz, 753 Hz, 1250 Hz
p ractice problems2
Practice Problems
  • A violin string that is 50.0 cm long has a fundamental frequency of 440 Hz. What is the speed of the waves on this string?
ad