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