Decibel meter app

ddc said:

Android phone: Is there a recommended app?

If not is there a "best of the not very good" ???

Thanks!

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Phone apps are typically not very responsive (quick enough) for gunfire.

You really need a special meter to be able to get a good measurement of gunfire. The noise from all firearms is a very short pulse that is missed by all smart phone apps and most inexpensive sound meters.

Cell phones don't have pressure microphones or a fast enough rise time to pick up gunshots or other fast impulse noises. They are random number generators.

To meter gunshots with any semblance of accuracy, your minimum investment will be in the neighborhood of 3-5 grand for a properly reconditioned/refurbished analog meter, preamplifier, microphone adapter and 1/8" or 1/4" pressure microphone. And even with a meter like the B&K 2209, you need to have multiple cans that have been tested on modern equipment like the B&K Pulse system across a range of ~110-150 dB that you can use as controls to calibrate the old analog meter. Just using a digital calibrator or pistonphone, you'll be off by quite a bit. The 2209 meter has a 20 μs rise time, and the peaks of gunshots can be as short as 3-7μs, so they may miss the highest one. I say this as a guy who uses a 2209 with control cans because I can't afford 30 grand for a Pulse right now.

On my iPhone I use a very well designed app called SPLnFFT. You may have to check the Android availability. A quick search seems to indicate it is iOS only, and the recommended alternative Android app is Sound Meter.
See the research article
Testing the accuracy of smartphones and sound level meter applications for measuring environmental noise

Spectroid is quite useful for metering a number of sound characteristics, including pitch range, intensity, whatever is happening acoustically, and the graphing presentation shows a running history for about 15 seconds.

2209's have been proven to not produce repeatable data. B&K pulled a dozen for a test and only 1 had data that was statistically the same as data from the same events as recorded on a PULSE. I say this as someone who owns 2 2209's and wasted years of R&D on questionable data before the PULSE was available. The Larson Davis LxT does not have the sampling rate required to capture the rise times of gunshot events. Bottom line, the only data that is valid is data recorded on a B&K PULSE while using the correct and repeatable experimental setup.