Sound What is Sound? Frequency and pitch of sound Speed of sound What is sound intensity? What is resonance? Ultrasound and infrasonic

1. Sound
Tabassum Ishra

2. What is sound?
 Sound is produced when something vibrates.
 A sound wave is the movement of alternating
compressions are rarefactions. Sound travels longitudinal
waves.
 When air particles are compressed or bunched up together
they are called compressions.
 When the air particles are spread out the are known as
rarefactions.
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3. Sound Wave

4. Speed of sound
 The more closely particles in a medium,
the faster sound will travel through.
 Sound travels faster through solids than
liquids, and faster in liquids than gases.
 Sound also travels faster in warm air than
cool air because the air is moving with
greater kinetic energy

5. Speed of sound
Material Speed of Sound (m/s)
Air (at 0 degree Celsius) 331
Air (at 18 degree Celsius) 342
Water 1440
Wood 4500
Steel 5100

6. Sound
 Hard surfaces reflect sound waves. Reflected
sound waves are called echoes.
 Examples:
 Sonar
 Echolocation
 Soft materials absorb sound was and convert it
to heat. This reduces reverberation.

7. Frequency and Pitch Sound
 The pitch of sound is related to the
frequency of a sound wave. The greater the
frequency, the higher the pitch
 Volume of a sound is related to the
amplitude of a sound wave The greater the
amplitude the greater the volume.

8. What is sound intensity?
 Sound intensity is the energy that the sound
wave possesses. The greater the intensity of
sound the farther the sound will travel and
the louder the sound will appear.
 Loudness is very closely related to intensity.
Loudness is the human perception of the
sound intensity. The unit for loudness is
decibels.

9. What is 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.

10. Ultrasound and Infrasound
 Ultrasound is the name given to sound
waves with frequencies above our hearing
range. ( 20-20000 Hz)
 Frequencies lower than man hearing range
is infrasound.