What do you know about decible meters ?

[Gertrude]

Probably not the correct gate to put this in, so move it if necessary please.

I recently purchased a cheap decible meter, and was wondering if there is a easy way to tell if it is reading accurately ?
here is a pic of the one I got off of ebay for under $20,



I'd like to know how accurate it is, so that I can compare it to my other AG's.
 Sure, I realize that for that simple test it does not really NEED to be accurate, because I will mainly be testing for the differences between the rifles reports,...
 But, it would also be nice to know if I am getting accurate readings.
 
So, is there any basic tests to check for sound level accuracy of this particular meter ?
 maybe the average sound level of regular conversation ?, or dropping something on concrete from "x" feet  off the ground ?
I dunno,... just askin'

[02stampede]

The most definitive way would be to send it off to a calibration lab. Too many variables to account for otherwise.

[rsterne]

I tried a cheap meter for recording airgun shots and it wouldn't even give consistent readings on one gun at one distance.... so I returned it.... I believe the "samplng rate" was too low, so it wasn't always recording the sound of the shot....

Bob

[Mr Sasquatch]

There are several apps for the iPhone available for free. You could get a couple of them and just compare the results. Short of having your device custom calibrated, this will give you some indication of how accurate your meter is.

[ac12]

A problem is some/most are probably designed for a constant level of sound.
The single instantaneous sound of a gun shot may not be properly handled by those meters.
It is similar to the old peak vs. averaging VU meters on tape decks/recorders back in the 70s.  With an averaging meter, you did not see some of the audio peaks that would be distorted in the recording.

[BenjiHunter]

Here are some data.

Key Features
Highlights
This unit was designed according to following standards:
A. International electrician committee standard: IEC PUB 651 TYPE2
B. US national standard: ANSI S1.4 TYPE2
Measuring range: 30~130 dBA
Accuracy: ±1.5 dB
Digit & Resolution: 5digits & 0.1 dB
Frequency response: 31.5Hz ~8.5KHz
Sampling rate: 2times/second
Microphone: 1/2 inch polarization capacitance microphone
Max HOLD
Low battery indication
Auto backlight display
http://www.lightinthebox.com/digital-sound-level-meter-gm1351_p301897.html

[sperho]

With a sample rate of 2 Hz, that meter is dead in the water for what you want to do with it.  Would be good for constant sounds, but not a shot from a gun.

[Plekto]

To capture the impulse of a rifle or airgun, it needs to sample closer to 30-40ms and have a frequency response of upwards of 20Khz, because it's the high frequency sounds that damage your hearing the most.