Vocal chords vibrate 100-1,000 times a second. You can feel them vibrate if you lightly touch a finger on your throat when you speak.
The localised compression of the air is called condensation. The air pressure is greater than normal atmospheric pressure.
The localised expansion of air is called rarefaction. The air pressure is less than normal atmospheric pressure.
Sound waves are longitudinal waves.
Fast - about 330 m/s for sound in air, 1,500 m/s in water and 5,000 m/s in steel.
Medium - Such as air, water or metal. Sound waves cannot travel in a vacuum.
High Pitched - Many vibrations per second.
Low Pitched - Fewer vibrations per second.
The Phonograph was invented by Thomas Edison in 1877. The mechanical recording of sound took many years to perfect but eventually reliable recordings were made.
The horn acts as a funnel, amplifying the vibrations or sound waves in the air, and forces them into a small point.
Diaphragm - A thin membrane like a drum skin. On the island, the bottom of a tin can was used.
Moves along - Driven by the nut on the cylinder's spindle screw thread.
Groove - The depth of the groove is determined by the amount and type of vibration that the stylus receives.
Record - As a series of tiny 'hill and dale' undulations within the groove.
Pushed In - If the handle is turned, the needle digs a grove into the wax - if the groove disappears at some points along the spiral, the wax is uneven and needs to be shaved off a bit more.
Even Rate - 2-3 times a second.
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