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Calibrated dBA meter or calibration noise source.

Posted By: 360view

Calibrated dBA meter or calibration noise source. - 06/08/21 12:50 PM

Anyone on Moparts own
one of the precision noise sources to calibrate dBA sound level meters,
or a recently calibrated meter?

I am looking for someone to measure the sound level of some Chrysler horn at a set distance away
so I can use it to do a rough calibration.

Looking online I have seen that locomotive horns have a dBA sound level standard from 100 feet away,
and aftermarket horn manufacturers give specs

https://www.law.cornell.edu/cfr/text/49/229.129

https://autoquarterly.com/best-loud-car-horns/

https://www.chem.purdue.edu/chemsafety/Training/PPETrain/dblevels.htm

I am trying to roughly check the accuracy of the free noise app for iPad/iPhone from the National Institute for Occupational Safety and Health.

https://www.cdc.gov/niosh/topics/noise/app.html

Do some of the automobile magazines routinely measure vehicle interior noise levels?
Posted By: jcc

Re: Calibrated dBA meter or calibration noise source. - 06/08/21 02:03 PM

Why the special concern with accuracy?

There are so many variables beyond the meter that will effect the outcome, or GIGO.

Any decent meter will get you in the ballpark, unless you are doing final certification tests, and then hurdles/test conditions are much higher than just using a calibrated meter.
Posted By: 360view

Re: Calibrated dBA meter or calibration noise source. - 06/09/21 12:35 PM

I just want to be sure this App is in the ballpark” of sound level.

It was made by US Government employees in Washington DC.
What could possible go wrong?

smile
Posted By: 6PakBee

Re: Calibrated dBA meter or calibration noise source. - 06/09/21 12:58 PM

Originally Posted by jcc
Why the special concern with accuracy?

There are so many variables beyond the meter that will effect the outcome, or GIGO.

Any decent meter will get you in the ballpark, unless you are doing final certification tests, and then hurdles/test conditions are much higher than just using a calibrated meter.


Absolutely true. I recall a lengthy discussion at a city council meeting about citing "loud" cars using a dB meter. The police chief said it was a waste of time because there were too many variables in a real world situation to make the readings accurate and/or repeatable.
Posted By: 5thAve

Re: Calibrated dBA meter or calibration noise source. - 06/09/21 03:56 PM

Some of the phone apps are pretty accurate compared to an actual meter but some are way off and it depends on the phone it's installed on too.
Posted By: jcc

Re: Calibrated dBA meter or calibration noise source. - 06/09/21 09:24 PM

Originally Posted by 360view
I just want to be sure this App is in the ballpark” of sound level.

It was made by US Government employees in Washington DC.
What could possible go wrong?

smile


Everything? grin

Its probably a clandestine speech monitoring app anyway if you have heard the latest law enforcement news. eek
Posted By: 360view

Re: Calibrated dBA meter or calibration noise source. - 06/10/21 10:46 AM

Originally Posted by 5thAve
Some of the phone apps are pretty accurate compared to an actual meter but some are way off and it depends on the phone it's installed on too.


My hope is to get 2 “standard noise levels” on the cheap:

1. Some automobile horn measured so many feet away for “loud” standard sound. (Approximately 95 dBA)
Second choice would be one those “Lost in the Wilderness mouth whistles”

2. The noise level of some automobile interior traveling at 70 mph over smooth blacktop pavement for quiet standard sound. ( approximately 65 dBA)
Second choice would be a common telephone ring tone from a common cell phone with the volume set middle position.

This is like checking a thermometer in a stirred ice bath, then in boiling water corrected for altitude.
Posted By: 360view

Re: Calibrated dBA meter or calibration noise source. - 06/10/21 09:21 PM

https://alexonautos.com/cabin-noise/

The following seem to be measured at a steady 55 mph on a smooth road.

2017. Chrysler Pacifica 3.6L V6 70 dBA

2017 RAM 1500 Crew Cab Short Bed V8 74 dBA

2015 RAM ProMaster City 74.5dBA

2021 Jeep Compass 72 dB

2014 Jeep Cherokee Limited 3.6L 68.5dBA


2021 Ford F-150 Hybrid 69.5 dBA

2021 Ford F-250 Tremor 72 dBA

2016 Ford Explorer Platinum 71dBA


2014 GMC Sierra Denali 6.2L 67dB

Posted By: 360view

Re: Calibrated dBA meter or calibration noise source. - 06/11/21 10:47 PM

maybe an electronic whistle for the high dBA end

https://www.amazon.com/Yukee-Electr...d+whistle&qid=1623451095&sr=8-20
Posted By: 360view

Re: Calibrated dBA meter or calibration noise source. - 06/15/21 10:01 PM

Turns out I already had a “Storm Whistle” among my rafting stuff.

The Storm whistle manufacturer claims that a strongly blown Storm Whistle makes 118-120 dBA in a “soundproof room.”

https://www.stormwhistles.com/frequently-asked-questions

When I blow the Storm whistle by mouth directly into the tiny microphone hole of the iPad Air 2 the NIOSH app reads 98 dBA instantaneously.

To get the maximum output I taped the Storm whistle to the output of a battery powered air blower and the reading on the NIOSH app rose to 102 dBA.
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