1. Recording Arts…Audio Fall 2014

2. Range of Human Hearing 20 Hz – 20,000 Hz or 20 Hz – 20 kHz

3. Range of Hearing http://www.youtube.com/watch?v=2G9Q-r2leyw Ear Training http://homerecording.about.com/od/homestudiobasi cs/a/test_tones.htm The Mosquito Hearing Device http://www.youtube.com/watch?v=eoa8eSf2NgQ&N R=1

4. 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.

5. 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.

6. 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

7. Sonic BOOM! This is what happens when you exceed the speed of sound…a visual and audible event… http://www.youtube.com/wa tch?v=6o0zmafxTmE

8. 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.

9. Sound Waves

10. 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.

11. 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

12. 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

13. 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

15. 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

16. 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