Terms cont’d.

Dynamics

Dynamics

• Relative loudness or softness of a sound.

• A trumpet soft is still louder than an acoustic guitar played loud!

Decibel

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

SPL - Sound Pressure Level

• Auditory threshold at 1 kHz

• 0 dB

SPL - Sound Pressure Level

• Light leaf rustling, calm breathing

• 10 dB

SPL - Sound Pressure Level

• Very calm room

• 20 - 30 dB

SPL - Sound Pressure Level

• Normal conversation at 1 m

• 40 - 60 dB

SPL - Sound Pressure Level

• Washing machine, dish washer

• 50-53 dB

SPL - Sound Pressure Level

• TV (set at home level) at 1 m

• approx. 60 dB

SPL - Sound Pressure Level

• Handheld electric mixer

• 65 dB

SPL - Sound Pressure Level

• Passenger car at 10 m

• 60 - 80 dB

SPL - Sound Pressure Level

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

• 85 dB

SPL - Sound Pressure Level

• Traffic on a busy roadway at 10 m

• 80 - 90 dB

SPL - Sound Pressure Level

• Jack hammer at 1 m

• approx. 100 dB

SPL - Sound Pressure Level

• Jet engine at 100 m

• 110 - 140 dB

SPL - Sound Pressure Level

• Hearing damage (possible)

• approx. 120 dB

SPL - Sound Pressure Level

• Vuvuzela horn at 1 m

• 120 dB

SPL - Sound Pressure Level

• Threshold of pain

• 130 dB

SPL - Sound Pressure Level

• Jet engine at 30 m

• 150 dB

SPL - Sound Pressure Level

• M1 Garand rifle being fired at 1 m

• 168 dB

SPL - Sound Pressure Level

• .30-06 rifle being fired 1 m to shooter's side

• 171 dB (peak)

SPL - Sound Pressure Level

• Rocket launch equipment acoustic tests

• ~165 dB

SPL - Sound Pressure Level

• Stun grenades

• 170 - 180 dB

SPL - Sound Pressure Level

• Theoretical limit for undistorted sound at 1 atmosphere environmental pressure

• ~194.094 dB

SPL - Sound Pressure Level

• Shockwave (distorted sound waves > 1 atm; waveform valleys are clipped at zero pressure)

• >194 dB

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.

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).

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.

Compression

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.

Normalize

• Before After

QuickTime™ and a decompressor

are needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.

QuickTime™ and a decompressorare needed to see this picture.

Add compression

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”.