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How loud is 75 Db.a

I have purchased an industrial shredder. The noise it produces is 75
Db.a. How loud is this? If anyone could give me any exmples of
popular sounds which match this volume i would be greatful. Would i
require ear protectors?

It would be easier for me to switch the machine on, but i do not have
phase 3 power in the unit i am in. I will have in the new premises.

Hope someone can help.

Regards,
Anthony
 
P

Phil Allison

Jan 1, 1970
0
** Groper alert !

I have purchased an industrial shredder. The noise it produces is 75
Db.a. How loud is this?


** Similar to a kitchen blender, electric drill or vacuum cleaner at a few
metres range.

Kinda annoying to talk over.




....... Phil
 
D

Don Bruder

Jan 1, 1970
0
I have purchased an industrial shredder. The noise it produces is 75
Db.a. How loud is this?
Quite.

If anyone could give me any exmples of popular sounds which match
this volume i would be greatful.

Google is your friend.
Would i require ear protectors?

Yes.
 
Why don't you turn it on and listen to it??? Maybe you can hear how
loud it is and then you know how loud 75db is.....(Did I really have to
think of this myself???)
 
D

Don Bruder

Jan 1, 1970
0
Why don't you turn it on and listen to it??? Maybe you can hear how
loud it is and then you know how loud 75db is.....(Did I really have to
think of this myself???)

He said he doesn't have the right power conenction where he is currently.
 
Normal Breathing 10dB...
Soft whisper (at 5m) 30dB...
Normal Conversation 60dB
Busy Traffic 70dB
Average Factory 80dB
Niagra Falls 90dB
 
Simply reading my message would tell you that this is not possible.
Did i really have to point THIS out myself?. No one else had the same
problem.
 
C

chuck

Jan 1, 1970
0
I have purchased an industrial shredder. The noise it produces is 75
Db.a. How loud is this? If anyone could give me any exmples of
popular sounds which match this volume i would be greatful. Would i
require ear protectors?

It would be easier for me to switch the machine on, but i do not have
phase 3 power in the unit i am in. I will have in the new premises.

Hope someone can help.

Regards,
Anthony

Interesting question, Anthony.

Unfortunately, your question is unanswerable as posed. Suppose you could
measure the sound pressure level of your machine. What do think it would
be? Surely it would depend on how far from the machine you made the
measurement. Across town, you wouldn't be able to detect any sound
pressure from it. The shredder datasheet most likely provides
information on the distance from the machine at which the measurement of
75 dBA was made.

You cannot directly compare 75 dBA from the shredder to a vacuum
cleaner, because in the case of the shredder, the distance at which the
measurement was made has not been given, and in the case of the vacuum
cleaner, neither the sound pressure level, nor the distance at which
that level (if it existed) would have been measured.

What you need in order to answer your question is: dBA of shredder at x
feet and dBA of vacuum cleaner at y feet. With these numbers, you can
then find how much more (or less) loud the shredder is than the vacuum
cleaner when both are at some distance z from you. I think that is what
you are looking for.

If you'd like to see how the math is done, you might check out the
following link:

http://www.engin.umich.edu/class/ioe433/Noise/NoisePbs.pdf
NoisePbs.pdf (application/pdf Object)

Hope that helps.

Chuck
 
P

Phil Allison

Jan 1, 1970
0
"chuck"
You cannot directly compare 75 dBA from the shredder to a vacuum cleaner,
because in the case of the shredder, the distance at which the measurement
was made has not been given, and in the case of the vacuum cleaner,
neither the sound pressure level, nor the distance at which that level (if
it existed) would have been measured.


** Just for fun, I measured my bog standard vacuum cleaner with a Rode SPL
meter.

Distance - 1.2 metres.

Location - my workshop.

The SPL reading was 74 dBA.


QED



........ Phil
 
J

jasen

Jan 1, 1970
0
I have purchased an industrial shredder. The noise it produces is 75
Db.a. How loud is this? If anyone could give me any exmples of
popular sounds which match this volume i would be greatful. Would i
require ear protectors?

It would be easier for me to switch the machine on, but i do not have
phase 3 power in the unit i am in. I will have in the new premises.

As I recall that's about as loud as an argument can get before bones are
broken.

I bet wikipedia has a table of that sort of stuff...

Bye.
Jasen
 
C

chuck

Jan 1, 1970
0
Phil said:
"chuck"



** Just for fun, I measured my bog standard vacuum cleaner with a Rode SPL
meter.

Distance - 1.2 metres.

Location - my workshop.

The SPL reading was 74 dBA.


QED



....... Phil

No cigar quite yet, Phil. We still don't know the distance at which the
75 dBA was measured for the shredder (well, at least I don't know). If
it was 1.2 meters, then by sheer coincidence you get the cigar. I won't
ask what caused you to choose 1.2 meters. ;-)

But if the shredder measured 75 dBA at 5 meters (for example), then how
much louder than the vacuum cleaner would the shredder be when measured
at the same distance (say 2 meters) from each? Twice as loud (3dBA)? Do
we have even the most remote idea at this point? Isn't that precisely
the question raised by the OP? We've told him that when standing ???
meters away from the shredder, it will be as loud as standing 1.2 meters
from a vacuum cleaner. I imagine he was hoping for something more specific.

There is a chart at:

http://www.sengpielaudio.com/TableOfSoundPressureLevels.htm

that shows an spl measurement of 75 dBA at a distance of 10 meters from
an unsilenced wood shredder (which, with 3-phase power, may be what is
involved here). I leave as an exercise for the curious the calculation
of this unsilenced shredder's spl at a distance of 1.2 meters. Hint: it
will be many times louder than a vacuum cleaner at the same distance.


Chuck
 
B

BobG

Jan 1, 1970
0
The A weighting rolls off the bass to approximate the inverse of the
Fletcher-Munson loudness curve, so DBA is useful for soft sounds. For
loud stuff, you want a flat weighting, like dBC. dBA is great for
making noisy stuff look quieter than it is, because it rolls off all
the loud low freq stuff.
 
P

Phil Allison

Jan 1, 1970
0
"chuck"
Phil said:
No cigar quite yet, Phil. We still don't know the distance at which the 75
dBA was measured for the shredder (well, at least I don't know).


** Read the OP's question in the header.

He only wanted to know how loud 75dBA is.


But if the shredder measured 75 dBA at 5 meters (for example), then how
much louder than the vacuum cleaner would the shredder be when measured at
the same distance (say 2 meters) from each? Twice as loud (3dBA)?


** A 3 dB level variation is NOT "twice as loud " - you ass.

It is merely a just noticeable increase.

The OP will have to make his own enquires with the supplier of the "
industrial shredder " for details on their test distance and methodology.




......... Phil
 
C

chuck

Jan 1, 1970
0
Phil Allison wrote:

SNIP
** A 3 dB level variation is NOT "twice as loud " - you ass.

It is merely a just noticeable increase.

Absolutely correct, Phil. I meant to say twice the sound pressure level.
 
T

terry

Jan 1, 1970
0
Normal Breathing 10dB...
Soft whisper (at 5m) 30dB...
Normal Conversation 60dB
Busy Traffic 70dB
Average Factory 80dB
Niagra Falls 90dB
..
Decibels are a logarithmic 'ratio' of relative power.
Strictly speaking it is incorrect to say dB.
Because the next question is decibels relative to what.

For example if a test tone is at a certain level and increases by about
3 decibels it will have twice the power of the original tone. But we
still won't know the actual power level of the original signal or the
new one.

It could be one micro watt increased by 3 dB to 2 micro watts.
Or one milli watt increased to two milli watts.
It could be 1000 watts and increase to 2000 watts.
All three are a 3 dB increase/relationship between two power levels.

Working mainly in telecoms for some 40 years, we usually had 'Reference
to one milli watt' or as our 'Zero dBm'. I recall we covered the math
about decibels in first or second year telecomms at Tech. College!

But there are others decibel (ratio) references.

Radio transmitter people for example may use used dBw 'Reference to one
watt'.

Also there were dBa (then mostly used as a noise reference level on
circuits). Zero dBa was IIRC equivalent to about minus 90 dBm, but was
frequency shaped to conventional voice telecommunication circuit
requirements.

Then audio people use 'Sound pressure level at a certain distance from
the centre of the cone of a loudspeaker'. a certain level being
considered, by them, as a zero reference.

Was happy to see one of the motoring magazines get it right; they
referred to noise levels within tested vehicles in dBa. Nice to know
somebody there with a good technical background knew what they were
referring to!

So decibels (With reference to Alexander Graham Bell, Scottish Canadian
immigrant, who invented the telephone) are one tenth of the logarithmic
ratio of two powers but are in themselves strictly meaningless.
 
P

Phil Allison

Jan 1, 1970
0
"terry"
Then audio people use 'Sound pressure level at a certain distance from
the centre of the cone of a loudspeaker'. a certain level being
considered, by them, as a zero reference.


** " 0 dB SPL " is an internationally defined level.

Equals a steady sound pressure of 20 uPa ( micropascals ), rms sine wave.

Was happy to see one of the motoring magazines get it right; they
referred to noise levels within tested vehicles in dBa.


** Then they got it WRONG !!.

The correct term is " dBA SPL " or simply dBA, if the context makes the
latter redundant.

dBA refers to the " A weighting " curve used in nearly all noise
measurements and noise standards.


Nice to know
somebody there with a good technical background knew what they were
referring to!


** LOL !!!

So decibels (With reference to Alexander Graham Bell, Scottish Canadian
immigrant, who invented the telephone) are one tenth of the logarithmic
ratio of two powers but are in themselves strictly meaningless.


** Not when someone asks: " how loud is XX decibels ?? "

The context is obviously sound pressure, the zero reference level
internationally defined and the term "decibel" is the universal way to
express the relative sound level.




........ Phil
 
F

feebo

Jan 1, 1970
0
Why don't you turn it on and listen to it??? Maybe you can hear how
loud it is and then you know how loud 75db is.....(Did I really have to
think of this myself???)

twat

*plonk*
 
B

Bob Masta

Jan 1, 1970
0
Phil Allison wrote:

SNIP


Absolutely correct, Phil. I meant to say twice the sound pressure level.

Actually, it's twice the sound *power*, but only the usual 1.414 times
the *pressure*.

Best regards,


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
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