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G4WYW > TECH 26.12.05 13:18l 88 Lines 3776 Bytes #999 (0) @ WW
BID : 769600G4WYW
Read: DL1LCA GUEST OE7FMI
Subj: Sound Intensity Levels
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Sent: 051226/1112Z @:GB7FCR.#16.GBR.EU #:19799 [Blackpool] FBB-7.03a $:769600G4
From: G4WYW@GB7FCR.#16.GBR.EU
To : TECH@WW
There are various scales of sound intensity and examples that are all
very useful. I like this example because I can relate to different
sounds and effects given which I have heard in my day to day life, but,
I hasten to add, I have so far avoided a level that ruptures ear drums!
I hope you may find this scale/example useful to you in evaluating the
loudness and intensity of sound.
When considering human responses to sound the dB(A) scale is used.
This scale incorporates a frequency weighting network which approximates
the responses of the human ear; that is frequencies below 1000 Hz are
differentially attenuated with respect to high frequencies which are
more annoying at the same intensity level.
The following tables gives a rough guide for some typical sounds.
Intensity Ratio dB(A) Sound/Effects
10,000,000,000,000,000 160 Ear drum ruptures
1,000,000,000,000,000 150 Upper limit of safe exposure
of body to continuous noise
Sensations of imbalance and
skin heating
100,000,000,000,000 140 Military aircraft at 30m
10,000,000,000,000 130 Threshold of pain
Pneumatic percussive tools
Hydraulic press at 1m
1,000,000,000,000 120 Threshold of discomfort
100,000,000,000 110 Jet aircraft at 150m
Discotheque well away from
loudspeakers
Powerful mower at 1m
Train whistle at 15m
10,000,000,000 100 Noisy food blender at 0.5m
Inside train compartment
when door is slammed
Lorry in narrow street
1,000,000,000 90 Upper limit of daily noise
exposure regarded by the
government as acceptable
Automatic lathe at 1m
Underground train
100,000,000 80 Inside small car
Noisy office
Alarm clock
10,000,000 70 Busy street
Large shop
1,000,000 60 Normal conversation at 1m
100,000 50 Quiet street
Inside average home
10,000 40 Quiet office
Quiet conversation
Residential area at night
1,000 30 Ticking of watch
Rustle of paper
Whisper
100 20 Quiet country lane
10 10 Body sounds such as blood
pulsing, heartbeat
1 0 Threshold of hearing
0 -0 Feather falling :-)
73 - Mel, G4WYW @ GB7FCR.#16.GBR.EU
Message timed: 11:12 UTC on 26 Dec 05
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