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SOUND. SOUND. KEY TOPICS NATURE OF SOUND AUDIO SPECTRUM RESONANCE & FORCED VIBRATION REFLECTION. VIDEO. Animation of an audio speaker as it creates sound. VIDEO. LONGITUDINAL WAVES. SOUND. SOUND IS THE COHERENT VIBRATIONS OF ATOMS OR MOLECULES IN SOLIDS, LIQUIDS AND GASSES.
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SOUND KEY TOPICS NATURE OF SOUND AUDIO SPECTRUM RESONANCE & FORCED VIBRATION REFLECTION
VIDEO Animation of an audio speaker as it creates sound.
VIDEO LONGITUDINAL WAVES
SOUND • SOUND IS THE COHERENT VIBRATIONS OF ATOMS OR MOLECULES IN SOLIDS, LIQUIDS AND GASSES. • INCOHERENT VIBRATIONS ARE CALLED HEAT.
SOUND SOUND SPECTRUM INFRASOUND < 20 HZ • AUDIBLE SOUND > 20 HZ • AND < 20 KHZ ULTRASOUND >20 KHZ
SOUND Sound Demo using an audio generator
SOUND • THE SPEED OF SOUND IN AIR IS APPROXIMATELY • 330 m/s • 1000 ft/s DEMO • THIS IS ALSO DESIGNATED MACH 1 • THE SPEED DEPENDS ON TEMPERATURE, PRESSURE AND HUMIDITY
VIDEO This video shows that there is a delay in the arrival of the sound you hear when a sound is produced by an event located at a distance.
RESONANCE • VIBRATING AT A NATURAL FREQUENCY • ENERGY CAN BE TRANSFERRED EFFICIENTLY TO A VIBRATING OBJECT VIA RESONANCE.
VIDEO The Tacoma Narrows bridge collapse is one of the most dramatic examples of resonance.
RESONANCE • RESONANCE IS USED TO PRODUCE MUSICAL NOTES WITH A DEFINITE FREQUENCY. • EXAMPLES OF VIBRATING OBJECTS • STRINGS • AIR COLUMNS • SURFACES (DRUMS)
FORCED VIBRATION • VIBRATING AT A NON-RESONANT FREQUENCY • IT IS OFTEN APPLIED TO THE AMPLIFICATION OF SOUND
PITCH THE AUDITORY PERCEPTION OF FREQUENCY
REFLECTION OF SOUND REVERBERATION • RE-REFLECTED SOUND THAT OCCURS IN CONFINED AREAS SO THAT THE REFLECTED SOUND CAN NOT BE DISTINGUISHED FROM THE SOURCE • EXAMPLE - EMPTY ROOM
REFLECTION OF SOUND ECHO THE SOUND IS THAT NORMALLY REFLECTED OUTSIDE OR IN LARGE ENCLOSED AREAS SO THAT THE REFLECTED SOUND CAN BE DISTINGUISHED FROM THE SOURCE.