Exterior ambient noise measurement?

[Timebandit2]

Hi, hope everyone is safe and well during pandemic/lockdown. Has anyone use REW to measure exterior noise levels from road traffic and ambient background noise succesfully, or would it be better to.purchase a hand held meter to the job? There's quite a few on amazon at varying prices , has any one got a recommendation on one ar a reasonable price? I'm finding the apps available for android/iOS not very reliable with huge variations in results. Thank you.

 

[DanDan]

You need an Integrated Measurement. Hardware that does that is very expensive. There are excellent apps for the iPhone in particular. For Noise only it is hard to better this https://www.cdc.gov/niosh/topics/noise/app.html
For the bigger picture studiosixdigital.com and faberacoustical.com both do Pro apps. Studio 6 also do mics up to Class 1 (Legal)

 

[Wayne A. Pflughaupt]

Has anyone use REW to measure exterior noise levels from road traffic and ambient background noise succesfully, or would it be better to.purchase a hand held meter to the job?

That would depend if you're trying to determine the frequency content of the noise, the dB level, single-reading or time-lapsed.

Regards,
Wayne

 

[DanDan]

On second thoughts..... Yes. REW does have Integrated measurement, Leq and Logging. It also has spectrum and RTA averaging.

 

[Timebandit2]

Thanks Dan for all your suggestions, I'm just wanting to get a reasonably reliant measurement of sound coming in from a window at differing times of the day, I'm not looking for anything legal or frequency specific. I've numerous apps both on Android and an oder version of iOS. On both devices across a number of apps difference the db levels can quite marked which is understandable due to the microphones. It's just a one off excersize so I content to be buying a new ipad or microphones just to use for a few hours. I could hire one for £60 plus vat , but one off amazon for about the same price or use REW with the microphone I already purchased to evaluate the rooms frequency response.

 

[Timebandit2]

Thanks for your reply Wayne, I'm after the level of noise during random times of the day to assist in decision making over new windows etc. Sound is like water and will find it's way in through any weakness in structures. So looking for some guidance on using REW to give some readings of ambient/traffic noise, rather than a inbuilt sweep for a few seconds. It's been invaluable in advising on room frequency response so I thought there might be a way to press gang it into doing it rather than purchasing more equipment that will hardly be used for a few hours.

 

[Wayne A. Pflughaupt]

Thanks for the info. Getting back to your original question, a hand-held meter would certainly be the most convenient, given that you just grab it and turn it on at the “random times of day” you feel inclined to take a measurement.

The reason prices vary so much is accuracy and features. Better accuracy and more features cost more money, obviously. The lowest priced meters will be Class 3 devices, which are supposed to be accurate +/- 1.5 dB. However in reality, many of the cheapest ones are only accurate +/- 2 dB. Class 2 meters are supposed to be accurate +/- 1 dB, and you’ll find those meters are more expensive. Class 1 meters are +/- 0.7 dB, although I don’t think I’ve ever been able to find one, as they are probably used primarily for industrial or legal purposes. I’m sure those will cost many hundreds of dollars.

Class 0 meters are laboratory reference devices, used to calibrate the others. However, if I understand correctly, a UMIK mic that has a sensitivity line in the calibration file technically should give dB-SPL readings with Class 0 or at the very least Class1 accuracy. Of course, in your situation that means taking the time to boot up the computer when you want to take a reading, or leave it on full time.

So basically, a hand-held meter wins with convenience, and REW wins with accuracy that’s far cheaper than any other comparable hand-held device.

Your choice.

Regards,
Wayne

 

[sam_adams]

Here are a couple of choices for class 1 SPL meters:

Class 1, ANSI S1.4, and NIST traceable option.

Class 1 with SD card datalogging.

 

[DanDan]

Class 1 costs thousands rather than hundreds! I have just bought an NTI XL2 and am selling an old but mint Bruel and Kjaer for 2K!

REW with your measurement mic is the best bet. Especially if you have a Cal File for the Mic.
Otherwise the iOS app is a good shot. Android, sorry no. iOS provides a facility for these Apps to bypass the High Pass Filter. For most purposes the internal mic is just as good as the external ones. That NIOSH app does Leq, which averages over sporadic sounds like passing cars etc. A 5 Minute 'sample' taken at different times is a very good way to assess matters. That is how pros do this.
There is great info on such matters on studiosixdigital.com

 

[Timebandit2]

Here's an promo being touted by a UK window company but I'm being sceptical. We all know lab results are produced under ideal conditions, for example, manufacturers will quote a frequency response on a speaker tested in an anechoic chamber but don't tell the unwary customer that they may have to spend substantial amounts of money on room correction. I suspect the same may be true of window manufactures! Here's a PR video of a well known UK company on you tube!

 

[sam_adams]

Class 1 costs thousands rather than hundreds! I have just bought an NTI XL2 and am selling an old but mint Bruel and Kjaer for 2K!

The XL2 is quit a bit different than a bare-bones class 1 SPL meter. The XL2 is a handheld audio analyzer with significantly more features, functions, and capabilities; therefore it commands a higher price. It is, by comparison, REW in the palm of your hand.

 

[Timebandit2]

The XL2 is quit a bit different than a bare-bones class 1 SPL meter. The XL2 is a handheld audio analyzer with significantly more features, functions, and capabilities; therefore it commands a higher price. It is, by comparison, REW in the palm of your hand.

That's the million dollar question really isn't it? Do I need REW in the palm of my hand for an hour or two when I can have REW in any room in the house when ever I need? It's just figuring out a reference volume settings and finding a way to log the readings browse at leisure...

 

[Timebandit2]

REW is quite a comprehensive bit of software with a learning curve, on e I had the basics sorted along with the guidance of a few nice people in here it was relatively easy to produce the reports required for correcting the room acoustic to a satisfactory environment, like wise, using white noise to get loudspeakers balanced was quite easy but this is a different use and probably not one it's designed for but hope springs eternal, I really don't need a new ipad that can run the latest iOS along with another mic or to buy an upmarket meter that would be used at the most for a few hours, I'll have a go over easter, I have a small 8 channel portable mixer i could just set it up, plug the Mic in there, plug mixer into laptop and record the results on on a screen capture of phone using nominal quiet street levels as a base line, there must be a way to do it

 

[DanDan]

There are certainly ways to do it.

 

[50210Mike]

This is quite timely - I joined to ask the same question regarding measuring Aircon noise from a noisy unit that my neighbour uses at night (other side of my bedroom wall).

REW has the very useful Logging feature and saves Log data to .txt files. You can also save a .jpeg or .png image snapshot of the log graph.

I've attached my data as an example. It's captured via a calibrated UMIK1

Huge thankyou to the REW team.

I do have one question though - I need a logger that can run automated (i.e. saving a log file each 12 hours or so). Does anyone know of one able to do this?

I've searched the internet for hours and not found anything.

My issue is a long-term ongoing thing and I just want to collect data in an automated way so that I can link it to a database and provide charts/graphs showing when their aircon turns on, and what volume. Currently with REW I need to set it up before I go to bed and then save the data manually in the morning.

I'd be happy to pay for it. My plan is to run an old laptop as a dedicated ambient noise measurement station using the UMIK-1 and perhaps REW.

(attached file is the .txt output in case anyone wanted a preview)

 

[John Mulcahy]

REW already does that, just select the option in the graph controls. See the help:

Selecting Log to file using date as filename saves logged data to files in the REW logs directory automatically whenever the logger is running (the directory location is shown in the About REW dialog box). Filenames are formatted as SPL-YYYY-MMM-dd.txt, e.g. SPL-2016-Apr-24.txt. If a file for a day already exists a number will be appended, e.g. SPL-2016-Apr-24-1.txt, SPL-2016-Apr-24-2.txt etc. A new file is created if the logging continues past midnight, with the new date. Note that the files can become very large if logging continues for a long period, growing at about 18 kB per minute. If the option to log to files is selected remember to check the REW log directory to remove files you no longer need.

 

[DanDan]

Take a look at studiosixdigital.com and faberacoustical.com
Both do iOS sound measuring software to a pro level. It can be useful to take a spectrum of the noise.