Real and Virtual SPL Meters

A couple of weeks ago a Facebook friend posted about how many SPL meters he still had in his possession. It was more than ten. Of course, this got me thinking about my own SPL meter stash…and the fact that I hadn’t looked at any of them in quite a while…like years…in recent memory when I’ve needed and SPL meter, I whipped out my iPhone…

The first thing I did after searching for and retrieving the three SPL meters I still own was to replace their batteries, which were all dead or dying, but fortunately none had leaked yet…which brings me to a sub-point – storing gear that uses batteries with the batteries inside their battery compartments is a bad idea…eventually, if you wait long enough, a battery, any battery, will leak its corrosive contents into the guts of the device it was supposed to power, rendering it in many cases into junk. I collect film cameras. They taught me the folly of leaving batteries in battery compartments…I’ve seen so many old Pentax Spotmatics and Nikon Nikkormats that were otherwise mint, spoiled by a leaking battery…

After putting fresh batteries in all three of my real-world SPL meters, a Radio Shack Digital, Aperion re-release of a Radio Shack analog meter, and a B&K type 2226 that I picked up for the cost of a twelve-pack at a guitar show, I decided to see if they would all give me the same read-out when I played a 1000 Hz sine wave. Did they match? Nope. When I did a calibration test, the Radio Shack Digital SPL meter died. New batteries and a helpful couple of slaps did not revive it. Then there were two…

Much to my surprise both the B&K and the Aperion gave me readings within 0.4 dB of each other, which is pretty good. I then ran the same tests on the four SPL apps I have on my phone, which were, in no particular order – Audiotools, Decibel Ultra, Decibel X, and Audio Tool to see how closely virtual SPL meters came to the “real ones. When used in A-weighted mode Decibel Ultra and AudioTools readings were within 0.5 dB of the B&K (one was 0.2 dB higher while the other was 0.3 dB lower. The other two apps, Decibel X and Audio Tool, wanted me to upgrade to a paid version before they would support A-weighted mode, only giving me “type z” in the freebie versions. Here’s a link to the differences between the different weighing systems.

So, I was also down to two SPL apps as well…But let’s be real, you only need one.

If I were to have only one SPL app on my phone or physical meter, I would go with Decibel Ultra. Why? Because even the freebie version has all the essential information you need from an SPL meter. Not only does it have two simultaneous readings – A-weighted and LC peak, but also a bar-graph level and frequency display to show which frequencies are dominant.

If you need one app that can do a lot more than merely measure SPLs I would suggest looking into the AudioTools suite of Apps.

Their SPL meter is $19.95US, but the other apps, which include acoustic analysis tools, line level input measurement, speaker tests, and even some design and installation tools, can be purchased a la carte. While quite a bit more expensive than the free apps, Audio Tools is worth it if you do a lot of testing in terms of saved time and repeatable results.

After checking out my two working SPL meters I returned them to their shelf, confident that until I need to confirm that the batteries are still not inside their battery compartments, they will remain, undisturbed, in their resting place. My iPhone SPL meter apps do everything and more the physical ones used to do, and I always have them available at my hip for use…but that B&K 2226 SPL meter sure is a nice, if now virtually obsolete, piece of kit…