Hi, would anyone know how to use absolute pressure sensor to measure low frequency spl? 10-100hz range up to 180db? Something similar like this: Wireless Bass Meter TE - wireless device for measuring high pressure sound
If the pressure sensor is designed to respond uniformly over that frequency range, you would use it as the manufacturer intended it to be used. Consult the data sheet and relevant application notes.
SPL is defined as described here: Sound Pressure
range up to 180db
Physical pain and severe ear damage occurs at about 140 dB SPL or higher.
1 Like
I moved your topic to an appropriate forum category @movox.
In the future, please take some time to pick the forum category that best suits the subject of your topic. There is an "About the _____ category" topic at the top of each category that explains its purpose.
This is an important part of responsible forum usage, as explained in the "How to get the best out of this forum" guide. The guide contains a lot of other useful information. Please read it.
Thanks in advance for your cooperation.
Might it be easier to use a (MEMS) microphone ... ?
Hi, @movox
Welcome to the forum.
Any reason why, rather than a convectional microphone insert?
Do you know what levels of pressure you will need to measure?
Tom... 
1 Like
Because normal microphone can't measure over 130db without distortion. Using pressure sensor you can easily measure over 180db
Hi,
What is the application?
Measuring Nuclear Bombs?
Tom..
Please post a data sheet for this sensor.
1 Like
But does that distortion actually matter?
You're not after sound quality - are you?
Again, details of the application would help.
This one says it'll do "nearly" 180dB:
https://www.edn.com/mems-microphone-pushes-aop-point-to-ultra-high-levels/
and that's a few years ago - so maybe they are at that point by now ... ?
Car audio subwoofer pressure measuring
It should be accurate as spl meters on car audio competitions. And they use sensor I just posted for their design.
Page 5 of the data sheet has a schematic of how to hook it up.
You only need 3 capacitors and one resistor
Good for 200dB spl
1 Like
so just do whatever they do?
I'd wonder about the sensitivity/accuracy and I wonder if you can get a usable signal-to-noise ratio.
The specs say the it goes down to 20Pa, which (i think) is 120dB SPL.
In any case you should try to calibrate it with a real SPL meter, at or near, the maximum the SPL meter can read.
Somewhere around 180dB you have zero atmospheric pressure during the negative-half of the soundwave (and double the normal atmospheric pressure at its peak) so the soundwave itself is clipped (distorted).
Note that SPL readings are normally A-weighted to compensate that our ears are most-sensitive at mid frequencies. As far as I know the A-Weighting doesn't go to the subsonic range.
A Shure SM57 or 58 virtually has no upper SPL limit but the frequency response is not flat and you'd have to calibrate the frequency response (as well as the overall SPL level). Standard measurement microphones come with a calibration curve but they are electret mics and they can't handle extreme SPS levels.
Be careful when testing.... Not only your ears but your woofers... A speaker's power rating is for program peaks... A 100W speaker is supposed to be OK with a 100W amplifier (undistorted) hitting 100W on the peaks and about 10-20W average. You'll fry it with continuous 100W test-tones. And if you test higher frequencies, midrange speakers and tweeters are only rated for their part of the sound. A "100" tweeter only has to handle the high frequencies which are weaker. also, you can get more (average) power of an amplifier if you push it into distortion.... If you push it hard-enough to turn a sine wave into a square wave you can get double the power and the added power is harmonics that can go to the midrange or tweeter.
Not that simple
It measure 20kpa to 250kpa and when doing nothing it measure 1.75v = around 100kpa.. so there must be a special way to program it.. because 100kpa is way over 170db I think
Have you actually worked out what the pressure is at 180dB.
Don't forget its a logarithmic scale.
20,000Pa = 20kPa
Tom...
Yes, this sensor is measuring 1.75v = 100kpa in free air.. because that is atmospheric pressure. But there must be the way for it to measure decibels correctly.
Wouldn't an MPXV7025G (gauge) sensor be a better choice than an MPXx6250 (absolute).
The ±25kPa of the 7025G can measure 182db SPL.
With the 6250 you're wasting a lot of your A/D range.
An Arduino with 10-bit A/D and a pressure sensor might only have a measuring range of ~50db.
Can't (shouldn't) use a non-ratiometric A/D with these sensors.
Leo..