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Recording Arts…Audio Introduction. Fall 2014. Range of Human Hearing 20 Hz – 20,000 Hz or 20 Hz – 20 kHz. Range of Hearing http://www.youtube.com/watch?v=2G9Q-r2leyw Ear Training http ://homerecording.about.com/od/homestudiobasics/a/ test_tones.htm The Mosquito Hearing Device
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Recording Arts…Audio Introduction Fall 2014
Range of Human Hearing 20 Hz – 20,000 Hz or 20 Hz – 20 kHz
Range of Hearing http://www.youtube.com/watch?v=2G9Q-r2leyw Ear Training http://homerecording.about.com/od/homestudiobasics/a/test_tones.htm The Mosquito Hearing Device http://www.youtube.com/watch?v=eoa8eSf2NgQ&NR=1
Sound Waves • Sound is a longitudinal wave which can travel through gases (air), liquids (under water) or solids (the Earth). • Sound cannot travel through a vacuum. In space no one can hear you scream. • When an object vibrates (moves backwards and forwards) in air it produces sound waves.
Sound Waves • The sound wave will have the same frequency as the frequency of the vibrating object which made it. • The speed of a sound wave depends on the density of the medium (substance) through which it is traveling. • Sound will travel faster through the Earth than under water, and faster under water than it will in air.
The Speed of Sound ~344 meters per second or 1130 feet per second at 70 degrees F Sound is a very slow energy, much slower than Light
Sonic BOOM! This is what happens when you exceed the speed of sound…a visual and audible event… http://www.youtube.com/watch?v=6o0zmafxTmE
Loudness and Pitch • The loudness of sound depends on the amplitude of the wave. The bigger the amplitude, the louder the sound. • The pitch of sound (how high or low the note is) depends on the frequency of the wave. The higher the frequency, the higher the pitch.
Frequency: Frequency is defined as "the number of complete cycles (complete waves) in one second". Hertz is the unit of frequency (symbol Hz). 1 Hertz = 1 cycle per second.
Wavelength • Wavelength = Speed of Sound / Cycles per second • Vocalist sings the note A at 440 Hz. • 1130 / 440 = 2.56 ft or 30.72 inches • Low E on Electronic Bass ~ 40 Hz • 1130 / 40 = 28.25 ft or 339 inches • Screaming Guitar Lead @ 1175 Hz • 1130 / 1175 = .96 ft or 11.5 inches
Decibels AUDIO A logarithmic unit to measure volume/sound pressure.. • 0 db is the threshold of hearing • 10 dbis 10 times greater • 20 dbis 100 times greater • 30 dbis a 1000 times greater
Threshold of Hearing (TOH) 0 dB • Rustling Leaves 10 dB • Whisper 20 dB • Normal Conversation 60 dB • Busy Street Traffic 70 dB • Vacuum Cleaner80 dB • Large Orchestra 98 dB • Level Front Rows of Rock Concert 110 dB • Threshold of Pain 130 dB • Military Jet Takeoff 140 dB • Instant Perforation of Eardrum 160 dB
Vaccum Cleaner 80db • Rock Concert 110 db • Difference of 30 db or 1000 times louder • Therefore the average rock concert is equal to listening to 1000 vacuum cleaners running at the same time
What is the speed of sound? 1,130 feet per second • What is the range of human hearing? 20 Hz – 20 KHz (20,000 Hz) • When you ear hears an increase of 10db in a sound, how many times louder did that sound get? 10x • What if there was an increase of 20db? 100x • What about 30db? 1,000x