3000W Chinese Gensets Info.
professor95 wrote: EDIT ADDED 45/5/2013- When this thread started in March of 2005, I never expected to see it survive this long or amass the quantity of information that has been shared here. In...
Forum Discussion
Wow Guy, You bring back fond memories of discussions about acoustics, decibels, Metrology, and human preception from my college days...
Sound is one of the hardest things to measure.
The Bel is a measure of acustic energy. It is so large that it is not commonly used. Rather we the Decibel which is 1/10th of a Bel.
The Bel is a logarithmic measure of sound intensity or, more correctly acoustic pressure. Invented by the Bell telephone network in 1923 and named in honor of the inventor of the telephone, Alexander Graham Bell (1847-1922). If one sound is 1 bel louder than another, this means the louder sound is 10 times more intense than the fainter one. A difference of 2 bels corresponds to an increase of 10 x 10 or 100 times in intensity. The beginning of the scale, 0 bels, can be defined in various ways. Originally intended to represent the faintest sound that can be detected by a person who has good hearing. In practice, sound intensity is almost always stated in decibels. One bel is equal to approximately 1.151 293 nepers. The Decibel is a customary logarithmic measure most commonly used (in various ways) for measuring sound. The human ear is capable of detecting an enormous range of sound intensities. Furthermore, our perception is not linear. Experiment shows that when humans perceive one sound to be twice as loud as another, in fact the louder sound is about ten times as intense as the fainter one. For this reason, sound is measured on logarithmic scales. Informally, if one sound is 1 bel (10 decibels) "louder" than another, this means the louder sound is 10 times louder than the fainter one. A difference of 20 decibels corresponds to an increase of 10 x 10 or 100 times in intensity. The beginning of the scale, 0 decibels, can be set in different ways, depending on exactly which aspect of sound is being measured. For sound intensity (the power of the sound waves per unit of area) 0 decibels is equal 1 picowatt per square meter; this corresponds approximately to the faintest sound that can be detected by a person who has good hearing. A quiet room has a normal sound intensity of around 40 decibels, ten thousand times louder than the faintest perceptible sound, and a thunderclap may have an intensity of 120 decibels, a trillion times louder than the faintest sound. For sound pressure (the pressure exerted by the sound waves) 0 decibels equals 20 micropascals (µPa) RMS, and for sound power 0 decibels sometimes equals 1 picowatt. In all cases, one decibel equals about 0.115 129 neper and d decibels equal d(ln 10)/20 nepers.
In actual fact, we don't usually use Decibels, but rather a weighted scale known as DBA. DBA is sound measured the same as a Decibel, but with the high and low frequencies which the human ear doesn't detect well filtered out.
For those of you not familiar with the term, "Metrology" is the science of weights and measures. Throughout human history, we have strived to come up with ways to weigh and measure things. After all, you can't really know much about something until you can measure it.
Now, isn't all this clear as mud?
Okay, let's simplify things. Here are some common sounds, and their levels expressed in Decibels.
0 The softest sound a person can hear with normal hearing
10 normal breathing
20 whispering at 5 feet
30 soft whisper
50 rainfall
60 normal conversation
110 shouting in ear
120 thunder
Other actual things......
50 refrigerator
50 - 60 electric toothbrush
50 - 75 washing machine
50 - 75 air conditioner
50 - 80 electric shaver
55 coffee percolator
55 - 70 dishwasher
60 sewing machine
60 - 85 vacuum cleaner
60 - 95 hair dryer
65 - 80 alarm clock
70 TV audio
70 - 80 coffee grinder
70 - 95 garbage disposal
75 - 85 flush toilet
80 pop-up toaster
80 doorbell
80 ringing telephone
80 whistling kettle
80 - 90 food mixer or processor
80 - 90 blender
80 - 95 garbage disposal
95 - 110 motorcycle
100 snowmobile
110 baby crying
110 car horn
110 power saw
110 leafblower
120 chain saw, hammer on nail
120 pneumatic drills, heavy machine
120 jet plane (at ramp)
120 ambulance siren
125 chain saw
130 jackhammer, power drill
130 percussion section at symphony
140 airplane taking off
150 jet engine taking off
163 rifle
166 handgun
170 Shotgun
The above examples provided by The LeagueE For The Hard Of Hearing
The rest of the info in this post I took from various sources on the web as my memory isn't that good, and neither is my hearing.
Suffice to say that our preception of sound is very hard to quantify into numbers.
Cheers!
Sound is one of the hardest things to measure.
The Bel is a measure of acustic energy. It is so large that it is not commonly used. Rather we the Decibel which is 1/10th of a Bel.
The Bel is a logarithmic measure of sound intensity or, more correctly acoustic pressure. Invented by the Bell telephone network in 1923 and named in honor of the inventor of the telephone, Alexander Graham Bell (1847-1922). If one sound is 1 bel louder than another, this means the louder sound is 10 times more intense than the fainter one. A difference of 2 bels corresponds to an increase of 10 x 10 or 100 times in intensity. The beginning of the scale, 0 bels, can be defined in various ways. Originally intended to represent the faintest sound that can be detected by a person who has good hearing. In practice, sound intensity is almost always stated in decibels. One bel is equal to approximately 1.151 293 nepers. The Decibel is a customary logarithmic measure most commonly used (in various ways) for measuring sound. The human ear is capable of detecting an enormous range of sound intensities. Furthermore, our perception is not linear. Experiment shows that when humans perceive one sound to be twice as loud as another, in fact the louder sound is about ten times as intense as the fainter one. For this reason, sound is measured on logarithmic scales. Informally, if one sound is 1 bel (10 decibels) "louder" than another, this means the louder sound is 10 times louder than the fainter one. A difference of 20 decibels corresponds to an increase of 10 x 10 or 100 times in intensity. The beginning of the scale, 0 decibels, can be set in different ways, depending on exactly which aspect of sound is being measured. For sound intensity (the power of the sound waves per unit of area) 0 decibels is equal 1 picowatt per square meter; this corresponds approximately to the faintest sound that can be detected by a person who has good hearing. A quiet room has a normal sound intensity of around 40 decibels, ten thousand times louder than the faintest perceptible sound, and a thunderclap may have an intensity of 120 decibels, a trillion times louder than the faintest sound. For sound pressure (the pressure exerted by the sound waves) 0 decibels equals 20 micropascals (µPa) RMS, and for sound power 0 decibels sometimes equals 1 picowatt. In all cases, one decibel equals about 0.115 129 neper and d decibels equal d(ln 10)/20 nepers.
In actual fact, we don't usually use Decibels, but rather a weighted scale known as DBA. DBA is sound measured the same as a Decibel, but with the high and low frequencies which the human ear doesn't detect well filtered out.
For those of you not familiar with the term, "Metrology" is the science of weights and measures. Throughout human history, we have strived to come up with ways to weigh and measure things. After all, you can't really know much about something until you can measure it.
Now, isn't all this clear as mud?
Okay, let's simplify things. Here are some common sounds, and their levels expressed in Decibels.
0 The softest sound a person can hear with normal hearing
10 normal breathing
20 whispering at 5 feet
30 soft whisper
50 rainfall
60 normal conversation
110 shouting in ear
120 thunder
Other actual things......
50 refrigerator
50 - 60 electric toothbrush
50 - 75 washing machine
50 - 75 air conditioner
50 - 80 electric shaver
55 coffee percolator
55 - 70 dishwasher
60 sewing machine
60 - 85 vacuum cleaner
60 - 95 hair dryer
65 - 80 alarm clock
70 TV audio
70 - 80 coffee grinder
70 - 95 garbage disposal
75 - 85 flush toilet
80 pop-up toaster
80 doorbell
80 ringing telephone
80 whistling kettle
80 - 90 food mixer or processor
80 - 90 blender
80 - 95 garbage disposal
95 - 110 motorcycle
100 snowmobile
110 baby crying
110 car horn
110 power saw
110 leafblower
120 chain saw, hammer on nail
120 pneumatic drills, heavy machine
120 jet plane (at ramp)
120 ambulance siren
125 chain saw
130 jackhammer, power drill
130 percussion section at symphony
140 airplane taking off
150 jet engine taking off
163 rifle
166 handgun
170 Shotgun
The above examples provided by The LeagueE For The Hard Of Hearing
The rest of the info in this post I took from various sources on the web as my memory isn't that good, and neither is my hearing.
Suffice to say that our preception of sound is very hard to quantify into numbers.
Cheers!
