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→Interference: I wrote three more sections, baced on the same source.
===Interference===
===Interference===
“Interference is when sound waves bump into each other, decreasing the quality of the sound. Sound waves are areas of high followed by low pressure or closeness of molecules. The high areas are compressions and the low are rarefactions. When the compression of one wave fills in the rarefaction of another, the volume is lowered. When two compressions join, the sound is unnaturally louder. The sound waves of a tuning fork interfere with each other to some extent. If the tuning fork is turned while sounding, the volume rises and falls from interference. "Dead" spots in auditoriums are caused by sound waves canceling each other, causing the volume of those spots to be less.<ref name="Stevens & Warshofsky Chapter One" />
“Interference is when sound waves bump into each other, decreasing the quality of the sound. Sound waves are areas of high followed by low pressure or closeness of molecules. The high areas are compressions and the low are rarefactions. When the compression of one wave fills in the rarefaction of another, the volume is lowered. When two compressions join, the sound is unnaturally louder. The sound waves of a tuning fork interfere with each other to some extent. If the tuning fork is turned while sounding, the volume rises and falls from interference. "Dead" spots in auditoriums are caused by sound waves canceling each other, causing the volume of those spots to be less.<ref name="Stevens & Warshofsky Chapter One" />
===Diffraction===
“Diffraction” is when sound makes a sharp turn. The wave expands as it moves away from the source of the sound. When the wave goes through an open door, for example, it is expanding enough it to bump the molecules immediately to its left and right. This causes another wave a fraction as loud to expand from the edge of the door. An ant standing close to the left or right of the door would hear the sound. This sound would not be a loud as it would if standing in front of the door and hearing the primary waves. The secondary waves, starting at the edge of the door, do interfere somewhat with the primary waves.<ref name="Stevens & Warshofsky Chapter One" />
===Absorption===
“Absorption” is when sound waves lose energy and thus loudness by echoing around within a porous material. Examples of porous material are curtains, rugs, and acoustic tiles. Each time the wave bumps into the solid part in the porous material, some of its energy of motion goes into the solid and is stopped by the mass of the solid. The solid heats up a little from this. A mad scientist once exposed some mice to extremely high energy sound. After ten minutes or less, the intense sound waves had burned their fur. <ref name="Stevens & Warshofsky Chapter One" />
===Doppler effect===
The “Doppler effect” is when the sound is of higher pitch or lower because the sound source is moving. When a race car is coming toward the listener, its speed decreases the distance between one wave and the next, or else causes all the waves to arrive faster like a fly in the car. As the car moves toward the audience, the car’s sound to the audience is of higher tone than to the driver within the car. When the race car is moving away, each wave arrives less often than when the car was coming toward the listeners. When the car is moving away, its sound is lower notes than when the car was coming toward the grand stand.<ref name="Stevens & Warshofsky Chapter One" />
== Subcategories of Sound ==
== Subcategories of Sound ==