Hello Guys,
I want to use Audacity to record my noisy neighbors. While the sound is not too important to capture the decibel levels are. In other words I want to be able to show how high the decibel levels can reach at various times of the day and use that information as a “real world indicator” of noise. Any tips on this? And is there a particular view I can look at to see decibel levels via a flat mono microphone recording. Thanks
That’s messy. The dB numbers in Audacity represent absolute audio signal numbers where they “run out” at 0. All sound signals are lower than that and measured in negative numbers. -20dB is the volume of the test tone at the beginning of broadcast television video tapes.
There is no connection between those numbers and the loudness of the sound at the TV station in the control room. That sound goes up and down with the volume knobs on the console. So that’s the basic disconnect between the signals and physical events.
You are trying to measure dBSPL. dB Sound Pressure Level. That’s the one you use to measure actual physical objects. Jets taking off, printing press pounding, casual conversation, rock music, etc.
You can cross calibrate an existing microphone by exposing the microphone to specific sounds or noises and compare Audacity to a calibrated SPL meter like the Radio Shack Sound Meter.
http://www.radioshack.com/product/index.jsp?productId=12680845
The meter is perfectly accurate but doesn’t record anything. Audacity will record for hours, but isn’t accurate without a lot of work.
The catch when you cross calibrate Audacity and a microphone with the Radio Shack meter is you can’t change anything after that. You can’t use the computer for anything else and it’s best if you never turned any of it off.
So that’s the problem.
Koz
Also, a recording would not be “proof” as it is too easy to fake.
I presume that you’ve tried being nice to them and politely explaining the problem. They may not realise how bad the problem is.
In the UK the local government body (councils) would be the people to contact if neighbours did not respond to persuasion. Their sound level meters would be accepted as evidence by the courts, but a recording generally wouldn’t be accepted as evidence of the level of noise (unless proved to be associated with a meter reading). A recording would be evidence of the type of noise, which may be important (deep bass from pop music you can’t hear the “melody” of is regarded as being very obtrusive).
Gale
Thanks to all your kind replies. Regarding SPL, i found this site for a convenient way of obtaining a SPL meter. The specs seem good, any thoughts? http://www.studiosixdigital.com/spl_meter.html
Do you have an iPhone or second generation iPod? Those are the only hardware the software meter is calibrated for as far as I can see.
Gale
A hardware meter like that seems to be nearly the exact analog meter that Radio Shack used to offer. The key is that “ansi calibration” thing.
A software meter would be at the complete mercy of the iPod running it. It would be a very fancy Audacity with good graphics and fuzzy calibration.
Neither one of those microphones listed will give you a good C response. Certainly not the headset mic. Those are terrible.
You can try it.
You’re not going to tell us where you are, are you?
Koz
This is the correct tool for the job (or something like this)
Quick Overview
Measuring the noise levels of noisy neighbours and nuisance noise has been made simple and cost effective with the Noise Log, a long term logging sound meter system. The noise log records and measures noise levels which can then be played back and data analysed on a PC
Price (excluding VAT):
£2,364.00 (budget noise log system)
£2,816.00 (class 2 compliance)
£3,216.00 (class 1 compliance)
I would not expect the iPod App to meet the requirements of legislation and standards compliance, but it may help as a general indication of the noise level when discussing the issue with others. At a cost of £0.69 in the UK, it could be a fun App and a conversation point in many situations, though probably not the best start as a chat-up line.
Yes, To Koz I’m in America via the UK.
To be honest I need a product that will help me define SLP levels for a product design which relates to noisy neighbors that I’m developing. At least in the early stages I can use the iphone software or a radio shack/tandy SLP meter for $40 while I hash out raw product. You guys have put me on the right track. Thanks for that. Will try to kepp you updated with it.
When we put our screening rooms on-line, we hired someone to come out with their fancy-pants meters, microphones, and analyzers. It wasn’t that many thousands.
Koz