1. The Physics of Sound By: Andrew Reid

2. What is Sound? A wave that can have many different frequencies. Waves can travel through all substances unlike light which reflects. Sound reflects and goes through. Waves are invisible

3. Humans & Sound Humans can hear sounds with their eardrums. We can hear between 12 Hz and 20 KHz. Eardrums vibrate and this sends a message to the brain and that’s what we call sound.

4. Speed of Sound Speed varies depending on the substance and temperature. 20 degrees Celsius, sound moves at 343 m/s in air. Sound is measured in decibels. 191 is max without distortion. -The denser the substance is, the faster sound travels through it. - Molecules are closer together and allow the waves to pass through easier in denser substances.

5. Decibel Guide

6. Clashing Sound Waves 2 sounds that are the same pitch will collide with each other and make the amplitude larger. This causes a beating sound that you can hear. Instruments are almost in tune. Sound waves are just rarefaction and condensing at different times. To avoid getting the beating sound, play notes at the same time. 2 waves with different frequencies clash and form a new frequency, either constructive or destructive interference.

7. Mechanical Waves Sound waves need a medium to travel through. Ex. Place a radio in a box and put a vacuum through a hole in the box. Can’t hear the radio. Light does not need a medium, it is an electromagnetic wave (energy).

8. Overtone series Series of notes that are a perfect multiple of each other. P8 and P5 are the most noticeable and the farther up on the staff you go, the less accurate the sounds become.

9. Why does Sound get Weaker? The sound spreads out in all directions and then eventually loses energy. Sound travels farther in water because it travels faster and the salinity, temperature, and depth have effects on the speed.

10. THE END