Measuring and collecting data on aircraft noise
August 11, 2013 12:14 PM   Subscribe

I need to measure some noise, complicated environmental noise. And store the data. Aircraft noise. (Which is complicated to measure.) Some initial research is turning up that it could be done with equipment like a Real Time Audio Analyzer w 1/3 Octave Band Filters or equivalent. I need to do it separately from city-owned or airport owned equipment. I know there are experts who do this and the analysis is not easy. Best case scenario, there would be an individual or group which could be hired within the Chicagoland area to help. Next best thing would be the ability to collect data ourselves that could be analyzed later. Anyone familiar with the resources and strategies used for residents to collect data on aircraft noise?
posted by jeanmari to Technology (10 answers total) 1 user marked this as a favorite
 
You may try contacting the folks behind http://www.bezoekbas.nl

That site is done by an organization coordinating efforts by people living around Schiphol Airport with regards to noise pollution and complaints about aircraft noise.

I don't know any of them, but Schiphol Airport is in a densely populated area, and if somebody knows your answer, they may know who that somebody is.

The site is in Dutch, but the Contact link at the top right gives you contact information, and most people in the Netherlands understand English.
posted by DreamerFi at 12:36 PM on August 11, 2013


I do auditory neurophysiology research and we continually measure and calibrate our experimental rig using Bruel & Kjaer acoustic measurement equipment. While we do all of our analysis in Matlab using custom software written in-house, B&K has software that allows you to do some of the analyses with a graphical front-end. I'm not sure what kind of analysis you're planning on doing but you can start with a simple hand-held sound level meter that you can get at Radio Shack.

It seems like B&K also has hardware and software packages for monitoring airport noise.
posted by scalespace at 12:38 PM on August 11, 2013


Are you looking to create something like a noise contour map (warning: large PDF), just with information independent from what the FAA or the airport claims?

These are the guys that did the Chicago airport maps for the CDA. It might be hard to find a noise assessment company that doesn't already have airport authorities as a client.
posted by LionIndex at 12:40 PM on August 11, 2013


But, here's another firm. Looks like the key to the google-fu here is "environmental noise assessment"
posted by LionIndex at 12:42 PM on August 11, 2013


No, I don't know anyone there who does that sort of thing, but it's basically a measurement / instrumentation project.

Any number of consulting engineers would quote on it, if you have specs for the job.

If you have a purpose in mind, it make a difference in what kind of project it is, how long it takes, who can do it, and how much it will cost.

If, for instance, you are trying to abate/reduce noise of a particular type in a particular building and you simply want to roughly characterize the noise, approximate its magnitude and assess your reduction efforts, that's one price, X.

If you are going to court, and you need experts, NIST traceable measurements, and lots of analysis plus opinons, that's 10X.

It's just another form of data collection. I can see how some of it could be done quite cheaply from a recurring standpoint (i.e., how to make a capture mechanism that would get fairly faithful recordings (spectrally limited) every time that airplane noise happened), but might cost a bit for equipment rental.

In fact, to make such a setup, I'd configure a system USING rental instrumentation. Overall, it would be cheaper. You have to establish a duration for the measurements and fully describe the types of things you want to document.

Ballpark (not total guesswork) for doing a month's worth of analysis... 8 weeks of engineering time ($20k), $10k of equipment rental, $5k expenses and travel and you'd get a report for the cheaper approach. DIY, you can dodge the engineering and expenses. If you can find a really good, retired engineer with audio hardware and a helpful attitude, locally, you might get something really cheap. Tech school/engineering school seniors may need a project and this sounds good, subject to the relevant and customary caveat that they are inexperienced.

A day's worth of analysis would obviously be cheaper. A week, somewhere in the middle. Some of the equipment rental would be cheaper for a week, but it's not just the rental, it's figuring out what to rent, getting it, familiarization, installation, operation/attendance during test, data collection/organization, and post-processing.

The killer with stuff like this is that yes, you can DIY. You need to know the limits of what you are measuring. You need to know what's relevant to the measurement. You need to constrain the questions in order to make possible the measurements that SUGGEST the answers. You need to know how to interpret the results.

I've done this kind of stuff on a lot of physical quantities, ranging from highway instrumentation to quarry drilling, but with different electrical signals, not sound.

As with all things like this, the answer rotates around the words "it depends". More info needed for better answers.

Other mefi folk will chime in, and may have differing inputs, but that's my experience talking and i am happy to answer or elaborate privately if you don't want to publicize your project details. memail.
posted by FauxScot at 1:54 PM on August 11, 2013


I am an acoustical consultant in the Chicagoland area, though IANYAC and my firm typically does not do these types of measurements. Please consider calling a consultant listed on the National Council of Acoustical Consultants, many of whom do environmental noise measurements on a regular basis.
posted by maximum sensing at 2:04 PM on August 11, 2013 [1 favorite]


While you could DIY this, you're going to have to lay down a cast-iron audit trail that shows the calibration of your equipment and its operation within proper technical limits. The acoustic engineers I work with often use consumer-grade digital recorders (the M-Audio Microtrack was a favourite a few years ago) for sound monitoring, but they've been careful to set them up with a proper environmental noise microphone, wind screen and pre-amp, and included a traceable calibration tone at the start of each recording.

The city should be working to protect the health of its citizens. Its report should be able to stand up to third-party scrutiny against bias. If you're in Chicago itself, aircraft and airports are specifically exempt (11-4-2920) from any noise limits, unfortunately.
posted by scruss at 3:50 PM on August 11, 2013


While we'd love to do a non-challengable audit, we may just have the resources to raise questions instead of answering them.

The specifics are that the City of Chicago has been directing more and more of its aircraft traffic over only one area of the city, increasing the intrusive noise by a dramatic amount. In October 2013, this is about to get even worse. Compounding the problem is that some of the planes are lowering their landing gear (I think early, because I rarely saw this before) which increases the drag and the noise. They have stonewalled putting any measurement systems in the area to measure the increase in the environmental noise.

There have been instances in the past, because the city holds the recording systems and the data, of the city not really understanding the extent of the noise:

"The city's system is limited because its monitoring devices are in fixed positions--attached to utility poles and buildings--and because the system averages the noise at each location over a 24-hour period.

"They fold in the quiet times with the very noisy times. Our equipment will allow us to measure the noisy times and the areas where Chicago says there isn't any noise,"


Essentially, the suburbs got their own audio equipment and have been pushing for 70%~ of O'Hare's traffic to be directed over one area, and a new runway that will increase this even more opens October 2013.

We've been having trouble getting good data on the increase in noise levels, though we have data on increased traffic and the shape of the contour maps. There are groups that have been fighting this with petitions, organizing, etc. But they can't get data. And it has gotten so bad, that you cannot have the windows open or be outside at certain times of the day. It starts very early in the morning (these planes have woken up the house at 4:45 am) and end after midnight, sometimes going until 2 am. We've been told "It's not that bad" by folks who don't live here. We live about 13 miles from the airport and it is unceasing.

Again, we're not going to be able to use this data as definitive. But we need data and we're getting desperate.
posted by jeanmari at 10:37 AM on August 12, 2013


At the suggestion of a colleague, I downloaded an app on iPhone that can measure at different bandwidths and set it at the following:

- 1/3 octave
-Time decay (graph speed) very slow
-Max decay (white line jitter) Hold Maximum

-Show Maximums

Then I just hung out on the back porch for about 10 minutes. Obviously, this isn't calibrated or defensible. And I need to check with the experts as to what this actually means but you can see on the second screenshot the "maximums" just SHOT up when a plane flew over. At 250 Hz, the band shoots up to almost 68.

Without planes flying overhead, 250 Hz hovers a bit above 22.

I imagine that is reflecting how loud it gets. And this repeats for 2-3 hours at a time, with planes flying in practically on top of each other (seconds or minutes apart). Then stops for a few hours, then begins again.

It's jarring every time it happens, and how the anticipation of it is almost as bad as when it is actually on top of you. I can actually see my kids just tense up when they begin to hear that slow build.

Now to figure out a set up that has a calibrated mic and can store the data....
posted by jeanmari at 12:41 PM on August 12, 2013


Late with this, but if you are still monitoring this thread, here's a company I saw on a google+ hangout that makes sensors that can be attached to any android device.

Seems like one includes a microphone-type sensor.

Could be powerful enough and cheap enough to meet your needs.

http://www.valarm.net/
posted by tillei at 3:35 PM on August 19, 2013


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