Terms cont

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Terms contd.

• Dynamics

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Dynamics

• Relative loudness or softness of a sound.
• A trumpet soft is still louder than an acoustic
  guitar played loud!

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Decibel

• A measurement of volume.
• Not relative like musical dynamics, but objective.

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SPL - Sound Pressure Level

• Auditory threshold at 1 kHz
• 0 dB

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SPL - Sound Pressure Level

• Light leaf rustling, calm breathing
• 10 dB

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SPL - Sound Pressure Level

• Very calm room
• 20 - 30 dB

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SPL - Sound Pressure Level

• Normal conversation at 1 m
• 40 - 60 dB

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SPL - Sound Pressure Level

• Washing machine, dish washer
• 50-53 dB

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SPL - Sound Pressure Level

• TV (set at home level) at 1 m
• approx. 60 dB

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SPL - Sound Pressure Level

• Handheld electric mixer
• 65 dB

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SPL - Sound Pressure Level

• Passenger car at 10 m
• 60 - 80 dB

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SPL - Sound Pressure Level

• Hearing damage (over long-term exposure, need not
  be continuous)
• 85 dB

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SPL - Sound Pressure Level

• Traffic on a busy roadway at 10 m
• 80 - 90 dB

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SPL - Sound Pressure Level

• Jack hammer at 1 m
• approx. 100 dB

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SPL - Sound Pressure Level

• Jet engine at 100 m
• 110 - 140 dB

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SPL - Sound Pressure Level

• Hearing damage (possible)
• approx. 120 dB

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SPL - Sound Pressure Level

• Vuvuzela horn at 1 m
• 120 dB

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SPL - Sound Pressure Level

• Threshold of pain
• 130 dB

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SPL - Sound Pressure Level

• Jet engine at 30 m
• 150 dB

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SPL - Sound Pressure Level

• M1 Garand rifle being fired at 1 m
• 168 dB

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SPL - Sound Pressure Level

• .30-06 rifle being fired 1 m to shooter's side
• 171 dB (peak)

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SPL - Sound Pressure Level

• Rocket launch equipment acoustic tests
• 165 dB

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SPL - Sound Pressure Level

• Stun grenades
• 170 - 180 dB

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SPL - Sound Pressure Level

• Theoretical limit for undistorted sound at 1
  atmosphere environmental pressure
• 194.094 dB

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SPL - Sound Pressure Level

• Shockwave (distorted sound waves gt 1 atm
  waveform valleys are clipped at zero pressure)
• gt194 dB

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Musical Dynamics

• Musical Dynamics
• A piece of music may change in dynamic level
  throughout.
• Live music is especially good for hearing
  dynamics.
• Subtle variations in a performance by musicians,
  being sensitive to the sounds around them.

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Musical Dynamics

• A recording on CD is also excellent for capturing
  dynamics, as the available dynamic range is far
  better than on other recording media (tapes,
  records, and other analog formats).

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Compression

• Radio and mp3 formats are not ideal for hearing
  dynamics.
• The recording is modified with Compression.
• Compression squeezes the dynamic levels, making
  loud sounds softer, and soft sounds louder.

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Compression
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Normalize

• A way of modifying sound to peak at the maximum
  volume.
• Analysis of a computer sound byte will display
  the current volume level, as well as show the
  maximum potential volume before distortion /
  clipping / overload.

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Normalize

• Before After

Add compression
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The Loudness Wars

• The movement in audio recording and production
  that strives to get the most audio density into
  each recording.
• Record a sound, compress it, normalize it,
  compress it, normalize it, compress it, etc.
• Eliminates the distinction between loud and soft
  - everything is loud or hot.