Sound is produced by vibrations and travels as longitudinal waves through mediums, with speed varying based on density and temperature. The pitch is related to frequency, while the volume correlates with amplitude, and sound intensity indicates how far and loud a sound can travel. Concepts like resonance, ultrasound, and infrasound further explore sound wave properties beyond the audible range.

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.