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Sound. Sources of Sound. sound is a mechanical wave produced by vibrations that occur in a medium--generally air sound is a longitudinal wave. Transmitting Sound. in general, sound travels faster in solids and liquids than in gasses
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Sources of Sound • sound is a mechanical wave produced by vibrations that occur in a medium--generally air • sound is a longitudinal wave
Transmitting Sound • in general, sound travels faster in solids and liquids than in gasses • in liquids and solids, the medium is more compressed allowing for the wave to travel faster and longer
Speed of Sound in air • temperature affects the speed of sound in air • the warmer the air, the faster sound travels • in room temperature air, sound travels at about 343 m/s
Loudness • loudness is a subjective physiological sensation • it is measured in decibels (dB)—after Alexander Graham Bell, the inventor of the telephone • the pain threshold for humans is generally around 130 dB • ear drum ruptures occur between 160 and 185 dB
Frequency and Wavelength • frequency and wavelength have an indirect relationship • as frequency increases, the wavelength decreases
Pitch and Frequency • pitch and frequency are directly related • the higher the frequency—the higher the pitch of the sound emitted • the lower the frequency—the lower the pitch of the sound emitted
The Doppler Effect • an apparent change in pitch due to the motion of a source of sound
as a source of sound moves toward an observer, the wavelengths decrease in front of the source of sound resulting in an apparent higher frequency
as a source of sound moves away from an observer, the wavelengths increase behind the source of sound resulting in an apparent lower frequency