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How to decipher this Microphone sensitivity Chart for Choosing a SPL m
shyam.sunder91
post Dec 19 2013, 06:33
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I have a mic having sensitivity chart as below which has relative dB on y-axis showing

1V/0.1Pa
what does this convey how to read my mic's sensitivity



usually i was of the opinion that the microphone sensitivity is measure with reference to 20micropascals,but i read with this SPL measurements so i am wrong

so if i have to buy an SPL i have to correlate my SPL with the microphone i am using

because if my microphone i am using in my application picks up some sound according to its sensitivity and the spl meter i am purchasing may not give me the required SPL level that i have detected

when i have seen the frequency Weighting curves of the SPL meter they are shown as below



what do these convey ? are they trying to attenuate some frequencies or they are trying to follow human auditory model

so if i have to buy an SPL meter having correlative sensitivity as of my microphone would be better,what is your opinion am i going the right way in selection of an SPL
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saratoga
post Dec 19 2013, 07:02
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QUOTE (shyam.sunder91 @ Dec 19 2013, 00:33) *
I have a mic having sensitivity chart as below which has relative dB on y-axis showing

1V/0.1Pa
what does this convey how to read my mic's sensitivity


Thats a chart showing you how many volts you get per Pa as a function of frequency. So if you know the frequency, you can use that chart to figure out how many volts you'll get for a given pressure.


QUOTE (shyam.sunder91 @ Dec 19 2013, 00:33) *
what do these convey ? are they trying to attenuate some frequencies or they are trying to follow human auditory model


http://en.wikipedia.org/wiki/A-weighting

QUOTE (shyam.sunder91 @ Dec 19 2013, 00:33) *
so if i have to buy an SPL meter having correlative sensitivity as of my microphone would be better,what is your opinion am i going the right way in selection of an SPL


It depends on what you are measuring, its intensity, and how much gain your amplifier has.
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Kees de Visser
post Dec 19 2013, 13:34
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If you want to know exactly how many dB SPL you are measuring, you will need a calibrated system. You can do that yourself with a reference signal generator or have it done by a specialized company. The microphone sensitivity isn't too important, as long as you stay safely between its (soft sounds) noise and (loud sounds) distortion levels. But perhaps you don't need that level of accuracy.
If your neighbors complain about your loud music, you can measure at their place, do some sound isolation treatment and measure again to check if it made any difference. An absolute SPL value isn't too important here.
However if you want to close down a noisy pub because the music levels exceed the legal limits, you'd better have a calibrated system.
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DVDdoug
post Dec 19 2013, 22:15
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QUOTE
so if i have to buy an SPL i have to correlate my SPL with the microphone i am using
An SPL meter will have it's own mic included. Every SPL meter I've seen has a mic permanently built-in.

If you are using an addtional mic with some sort of meter, you should be able to (approximately) calibrate your setup to match.
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shyam.sunder91
post Dec 20 2013, 09:58
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the main question i am having is how would an microphone sensitivity advantage an SPL

why some high end SPL are so costly what the logic behind

i know the fact that a high end meter tries to put out parameters like Leq,FFT but where does that huge margin of cost come from

from above can i say that my microphone sensitivity is 12.5mv/Pa nominally,some SPL's i have seen having 30mv/Pa sensitivity

any ways these meters will be trying to give the SPL level of 94dB at 1KHz for 1Pa of pressure how is this microphone is creating difference
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includemeout
post Dec 20 2013, 10:33
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Just my two cents, but not having English as one's first language (just like myself) is no excuse for one not to use adequate (and universal) punctuation (?!;.-) for clarity's sake.

This post has been edited by includemeout: Dec 20 2013, 10:34


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shyam.sunder91
post Dec 20 2013, 11:03
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QUOTE (includemeout @ Dec 20 2013, 15:03) *
Just my two cents, but not having English as one's first language (just like myself) is no excuse for one not to use adequate (and universal) punctuation (?!;.-) for clarity's sake.



a bit LAZY laugh.gif
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Arnold B. Kruege...
post Dec 22 2013, 12:03
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QUOTE (shyam.sunder91 @ Dec 20 2013, 03:58) *
the main question i am having is how would an microphone sensitivity advantage an SPL


A sensitive mic might help building a SPL mic for low SPLs, that is less than 40 dB SPL.

QUOTE
why some high end SPL are so costly what the logic behind


High priced SPL meters are stable and rugged.

QUOTE
i know the fact that a high end meter tries to put out parameters like Leq,FFT but where does that huge margin of cost come from


I am unaware of that.

QUOTE
from above can i say that my microphone sensitivity is 12.5mv/Pa nominally,some SPL's i have seen having 30mv/Pa sensitivity


A really sensitive mic will probably have problems with really high SPLs like 140-160 dB SPL.

QUOTE
any ways these meters will be trying to give the SPL level of 94dB at 1KHz for 1Pa of pressure how is this microphone is creating difference


If you want to build a SPL meter then a microphone calibrator is probably in your future.
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Woodinville
post Jan 1 2014, 14:11
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If you can rent or borrow an accurate SPL meter, and you have any decent instrumentation mike, you can do pseudo-calibrated measurements using your mike, once you've established an exact system sensitivity.

The filters for A/C unweighted are public domain.

Octave is free.

Audacity is free.

You can also do frequency response, impulse response, and other measurements, for free.

I'm pretty sure I've cited the locations of some primitive FFT freeware for octave here already so I won't dig it up again.


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Speedskater
post Jan 1 2014, 17:20
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Just my random thoughts:

a] There are differences between a 'SPL meter' and a 'frequency calibration microphone'. (although with some effort one can do the other task)

b] Small diameter mics often have a better omnidirectional pattern than large diameter microphones.

c] Large diameter mics have better low level signal to noise response than small diameter microphones.

d] 'SPL' calibration is about reference (SPL) amplitude values (with specified frequency response curves).

e] A 'cal measurement mic' calibration is a frequency calibration (it may include pattern angle measurements) (it may not have any SPL information)

Earthworks has an interesting paper:

"How Earthworks Measures Microphones"
http://www.earthworksaudio.com/wp-content/...asures-mics.pdf


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