Decibel Meter: Recommendation?

stretchl

I'm thinking about a project that would involve measuring background noise levels in a number of settings.

Does anyone have a recommendation for a very portable, accurate decibel meter?

Thanks!

Moose68Bash

I use a Check Mate CM-140 from Parts Express ($129.99 now, but I think I got it on sale).

Works nicely for simple measurements of spl as I'm playing music. Good for "discussing" volume levels with my wife. :~)

I can't really speak to its accuracy for very precise measurements, which aren't required in my case. However, it can be calibrated.

pearsall001

Download an app on to your smart phone.

stretchl

Great ideas, both! Thanks!

BlueFox

I have both a Radio Shack digital SPL meter, and a phone app. A minor issue with these things is there is no way to know how accurate they are. For example, the iPhone app appeared to be a few db lower than the Radio Shack. Since the app is adjustable, I tweaked it to try to be close to the RS meter. I also downloaded the same app for my iPad, and it gave a different reading than on the phone. So, I tweaked it. Now they are all in sync.

While perhaps not 100% accurate, what the RS and apps provide is a tool to get an idea as to how much of a change in volume produces in SPL. For example, if I turn my pre from the 60s into the 70s I see the SPL go from the 90s into the 100s. Maybe the number isn't quite accurate, but I suspect the difference between the two settings is accurate.

nhhiep

Just get a free app for that
Matter

Polkie2009

I have the digital Rat Shack db meter. I was thinking there was a discussion years ago on AVS forum about the accuracy of the rat shack db meter. Could have also been difference between the older analog rat shack meters compared to the digital model. Maybe some others can chime in. All in all, I don't think it was a difference of more than 2 or 3 dbs..

Speedskater

An old Radio Shack analog SPL meter is surprisingly accurate at higher sound levels (say 50 or 60 dB SPL and up). But measuring background noise levels might be a challenge for and of the budget meters.

For others:
Don't confuse sound level accuracy for frequency response accuracy.

Mikey081057

I have both... one on my smartphone, and an el cheapo Scoche spl100f , <$30... The el cheapo might be more accurate, and can be calibrated where the smartphone one works with all droids and seems not very accurate... I mean it works with all androids and they might all have different mic sensitivities and can be blocked external stuff...I tend to think the $30 one is the more accurate of the 2, but I dunno...

stretchl

What I want to do is some sort of documentary project looking at possibly damaging noise pollution in out daily lives. Like those new air hand dryers in airports, etc. We've visited a couple of churches lately where the volume of the music in the youth areas seemed clearly damaging levels to me.

So I just wonder how pervasive noise at or about some recommended level is in our society.

Could be an interesting experiment.

BlueFox

We live in a heavily noise polluted society today. It would be an interesting project.

WLDock

If this is for personal use then a type 2/ class 2 meter will be fine. However, if this is for a more serious project then a type 1 /class 1 might be needed.

http://www.noisemeters.com/help/faq/type-class.asp

The cheap Radio Shack meter is actually pretty good for the price. When the correction is added, it makes for a very nice and cheap tool.http://www.hometheatershack.com/forums/rew-forum/86-interesting-info-rs-spl-meter-correction-values.html

I have the RS digital and actually took it to work (When I worked at MGM Grand Casino in Detroit) and to a stadium concert. I really wish I could have measure the noise levels when I played snare in the Mich. State Univ. Marching Band ages ago. Most in the drum line used ear plugs some of the time. However I think all were stuffing something in their ears during indoor rehearsals. Back then we used to cram the whole 300 member band into the general music room which was too small. So the percussion section was up front facing the band!!! Talk about loud!

Speedskater

Those corrections are for using the RS SPL meter as a cal microphone rather than an SPL meter.
As an SPL meter it will do just fine as it stands.

Devlon

BlueFox wrote: »

I have both a Radio Shack digital SPL meter, and a phone app. A minor issue with these things is there is no way to know how accurate they are. For example, the iPhone app appeared to be a few db lower than the Radio Shack. Since the app is adjustable, I tweaked it to try to be close to the RS meter. I also downloaded the same app for my iPad, and it gave a different reading than on the phone. So, I tweaked it. Now they are all in sync.

While perhaps not 100% accurate, what the RS and apps provide is a tool to get an idea as to how much of a change in volume produces in SPL. For example, if I turn my pre from the 60s into the 70s I see the SPL go from the 90s into the 100s. Maybe the number isn't quite accurate, but I suspect the difference between the two settings is accurate.

I was wondering about the accuracy thing. I just got a RS meter, and haven't taken it out of the box yet. As I am thinking it through it seems that the SPL accuracy of the unit itself would not be that important as long as you were using it to just set relative volume levels between speakers themselves in your system. Is my thinking about this correct?

Devlon

BlueFox: " A minor issue with these things is there is no way to know how accurate they are."

A friend of mine that mixes live sound uses a Test Tone CD that inherently plays each frequency at 60dB. I guess someone could calibrate a SPL meter say by letting it listen to these 60dB frequency sweeps. Just a thought.

BlueFox

Devlon wrote: »

BlueFox: " A minor issue with these things is there is no way to know how accurate they are."

A friend of mine that mixes live sound uses a Test Tone CD that inherently plays each frequency at 60dB. I guess someone could calibrate a SPL meter say by letting it listen to these 60dB frequency sweeps. Just a thought.

I guess I am missing something here. How do you know what level to adjust the volume to produce 60db? Every pre, amp, speaker, room combination will have different settings to create 60db. Obviously, you can't use the SPL meter since that is what is trying to be verified.

The only way I can think of is there has to be a controlled environment someplace that can be verified with a few calibrated SPL meters. Once you can accept that data then you can test your meter to determine its accuracy.

Devlon

I am not sure how this CD works exactly. This will be a rough explanation at best. I think that the idea is that every frequency on the disk (from 20-20K let's say) is outputted at the same relative volume level (and of course, has been recorded in the studio at the same volume level which is at 60dB). My friend "Robert" can tell the ability of a speaker to reproduce a certain frequency by the frequency's volume level compared to some overall target volume level he has set up. Some frequencies are inaudible. Some are horrendously loud. He boosts, and cuts with his parametric eq's based on these test tone volume levels. He used this method during the time he was doing sound for Amway's concert events.

I was thinking that one of these "test tones", in a midrange frequency, and set at a certain volume level say, could be used to level the SPL levels in the different speakers in a room?

BTW, how do most people use their SPL meters? What is the usual approach?

stretchl

I'm going to use it to measure various sources of noise pollution. I have tinnitus and some of the sound I hear is bothersome, painful, and I THINK well louder than what is healthy.

For instance, those superduper blade hand dryers that are coming online all around. I think they're MUCH too loud to be safe for one's hearing.

Second - Lots of music in public spaces, for instance, the stuff they play in my three-year-old daughter's dance class. I want to make sure it's not damaging her hearing.

Not sure what else, but I might make it some sort of project for publication.

Anyone got any other possibly unhealthy sources?

Moose68Bash

stretchl wrote: »

Anyone got any other possibly unhealthy sources?

I doubt the noise lasts long enough to do any damage to hearing, but my pet peeve is motorcycle noise from bikes with straight pipes.

WLDock

Speedskater wrote: »

Those corrections are for using the RS SPL meter as a cal microphone rather than an SPL meter.
As an SPL meter it will do just fine as it stands.

Exactly! I guess I should have said cheap pocket knife multi use tool. Saying the same thing....
Can be corrected to be used as a mic for REW or something. Can get a little more out of it for the money.

stretchl

Thanks, Moose. Ya... those loud pipes, though probably a decent safety feature, are irritating. I wonder about the riders, if they're not wearing ear protection.