recording arts…audio fall 2014. range of human hearing 20 hz – 20,000 hz or 20 hz – 20 khz
TRANSCRIPT
Recording Arts…Audio
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 Traininghttp
://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.
Sound Waves
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. o 1130 / 440 = 2.56 ft or 30.72 inches
• Low E on Electronic Bass ~ 40 Hz o 1130 / 40 = 28.25 ft or 339 inches
• Screaming Guitar Lead @ 1175 Hz o 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 db is 10 times greater
• 20 db is 100 times greater
• 30 db is 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 Cleaner 80 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