SOUND PRODUCTION

​Sound is produced by VIBRATION which is the back and forth movement of objects.

​

​Examples:

​1. Vibration of vocal cords

​2. Vibration of strings in guitar

​Sound Energy and Sound Wave

​Sound is a form of energy.

​It can travel in the form of sound wave, a MECHANICAL WAVE--it needs a medium to travel.

​

​Specifically, it is a LONGITUDINAL WAVE where the displacement of the particles is parallel to the direction of wave propagation

​Factors affecting the speed of sound

ELASTICITY- can return to its original form

• ​sound is faster in more elastic material; ex. steel (solid material)

​DENSITY- amount of mass per area or volume of material (for media of the same phase)

• sound is slower in denser objects; ex. Helium (less densed) vs. Air

TEMPERATURE- the average kinetic energy of atoms and molecules in a system

• ​sound travels faster in high temperature

Properties of sound

Reflection- bouncing back of wave as it hits a barrier

• ​ex. echo

• ​ex. reverberation-multiple echoes

Refraction- bending of sound due to changing media or temperature

• ​Ex. sound waves undergo refraction as it moves in air from high temperature to low temperature

​Speed of sound in air

​Dry air:

at 0°C, sound travels at 331 m/s

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​

​For every 1°C increase in temperature, there is a 0.6 m/s increase in speed

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​

EQUATION:

​

​

​

​where:

​ v= velocity

​ T= temperature in °C

What is the speed of sound in the air if the temperature is 29 °C?

What is asked: speed of sound

​Given: T= 29°C

​Equation:

​

​

​Solution:

​ v= 331 + (0.6) (29)

​ v= 331 + 17.4

​ v= 348.4 m/s

What is the temperature if the speed of sound is 349 m/s?

What is asked: Temperature

​Given: v= 349 m/s

​Equation: T= v - 331

​ 0.6

​Solution:

​ T= 349 - 331

​ 0.6

​ T= 18

​ 0.6

​ T= 30 °C