Sound

1
Sound

• How are sounds Classified?
• How are sounds produced?
• How are sounds different?
• How are sounds measured?
• How fast does sound move?

2
Sound Waves

• Each Sound wave has unique pattern
• Frequency
• Wavelength
• Amplitude

3
Sound mediums

• A medium is a material that sound, a form of
  energy, need to transfer
• Speed of sound
• Solid Fast speed
• Liquid Medium speed
• Gas Slow Speed
• Standard Temperature and Pressure 3.31 x 102
  m/s
• Vacuum No Sound

4
Frequency of Sound

• Pitch of the sound
• Musical notes there are 12 notes on a staff from
  A to G
• Bass Low frequency 0 to 300 Hz
• Mid range voice 300 to 6,000 Hz
• Treble High frequency, Above middle C note,
  6,000 to 20,000 Hz
• Spectrum of frequency

5
Amplitude of Sound

• Volume control
• Loudness
• Strength of the wave ( measured in db decibels)
• Energy of the wave

6
Reflection and Refractions of Sound waves

• Echo
• Reflection of sound off a surface (Acoustics
  (Greek akouein,to hear),. It is more commonly
  used for the special branch of that PHYSICS that
  deals with the construction of enclosed areas so
  as to enhance the hearing of speech or music.
• Reverb (Electronic echo)
• Resonance
• electronic envelope Helmholtz Resonator,
  spherical vessel of metal or glass with an
  opening and an earpiece on opposite sides.
• The ear canal acts enhancing frequencies in the
  range from 1000 to 4000 Hz (hertz, or cycles per
  second).

7
Speed of Sound

• Velocity(v) of a wave Frequency (f) times the
  wavelength (l)
• V f l
• The speed of propagation of sound in dry air at a
  temperature of 0 C (32 F) is 331.6 m/sec (1088
  ft/sec). If the temperature is increased, the
  speed of sound increases thus, at 20 C (68 F),
  the velocity of sound is 344 m/sec (1129 ft/sec)

8
Resonance of Sound

• Any oscillating object has a natural frequency,
  which is the frequency an oscillating object
  tends to settle into if it is not disturbed.

• The phenomenon in which a relatively small,
  repeatedly applied force causes the amplitude of
  an oscillating system to become very large is
  called resonance

9
Interference of Sound

• Constructive interference
• The displacement of the disturbance of 2 waves
  are the same (Similar sounds
• Frequency are the same or multiple.

• Destructive interference
• The displacement of the disturbance of 2 waves
  are the different (Unlike sounds)
• Frequency are the different or not a direct
  multiple.

10
Beats

• The pulse, or pattern of regular accents, of a
  musical piece can be broken into individual
  pulses, or beats

• a fractional symbol in which the numerator
  specifies the number of beats per bar, and the
  denominator specifies the relative note value
  assigned to one beat

11
Doppler Effect

• The frequency of the perceived wave is changed by
  the motion of the source
• Increasing Frequency when the source approaches
  the sensor
• Decreasing Frequency when the source increases
  the distance from the sensor

12
Summary

• Sounds are created by Moving molecule in the
  medium ( Solid, Liquid and Gases)
• Sounds are measured by Frequency, Wavelength,
  Speed, and Amplitude.
• Sounds can combine by interference
• Sounds can be changed by the Acoustics of the
  Area or the speed of the source
• (Doppler Effect)
• Sounds are used in many devices.