Sound and Music

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Sound and Music
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SoundCharacteristics of Sound
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Important There is no sound in vacuum! For sound
waves to travel you need an elastic medium!
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Speed of Sound in the Air v(331 0.6T)
m/s, Where T is the temperature in C.
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Conceptual Example Distance from Lightning
Strike
A rule of thumb that tells how close lightning
has hit isone mile for every five seconds
before the thunder is heard. Justify, noting
that the speed of light is so high that the time
for light to travel is negligible compared to the
time for sound.
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Loudness is related to the energy in the sound
wave. The pitch of a sound refers to whether it
is high, like a sound of piccolo or low like
string bass. The lower the frequency of sound,
the lower the pitch.
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Audible Frequency Range
The human ear responds to frequencies in the
range from about 20Hz to 20000 Hz. It could
slightly depend on individuals.
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Pressure Waves
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Sources of Sound Vibrating Strings and Air
Columns
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The lowest three frequencies in the string
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Interference and Sound Waves
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Beats
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Doppler Effect
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Shock Waves and Sonic Boom
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• Which of the following properties of a sound wave
  determines its loudness (or intensity)
  wavelength, speed, amplitude, or frequency? Which
  of these properties determines its pitch?
• How does the fundamental frequency of an organ
  pipe, which is open at both ends, change as you
  close one of the ends?
• How does the wavelength of the fundamental
  standing wave on a violin string compare with the
  length of the string?

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• You have an organ pipe that resonates at
  frequencies of 300, 450, and 600 hertz but
  nothing is between. It may resonant at lower and
  higher frequencies as well. Is the pipe open at
  both ends or open at one end and closed at the
  other? How can you tell?
• Same for 500, 700 and 900 Hz.
• An automobile sounding its horn is moving toward
  you at a constant speed. How does the frequency
  you hear compare with that heard by the driver?