There is not currently any android app that could be considered a valid measurement.
There is very high chance the microphone and preamp was clipping. At most you can use it for a relative measurement between two things done in the same time period. SPL is an absolute measurement.
There is too many variables on the platform, some phones do SRC without your knowledge. What filters on the microphone is there auto gain, noise processing and more? The latency can vary from 50 to 400 ms
Google till version 5 did not have good real time
scheduling which measurements tend to need. I have heard they have reduced the OS latency to 20ms still over 10 times too high but getting closer. By version 6 or 7 they should have it worked out.
I have no idea if the hardware latency is being reduced and if can ever be consistent.
There is a few useful ones on iOS platform, apple has also added a measurement mode function in the OS which allow the app to stop any conversation and processing that could corrupt the measurements. If you compare them the android apps you will understand how far the platform is behind in measurement.
http://www.studiosixdigital.com is way ahead of everyone. Andrew Smith's old company, before he sold it, made hardware based audio test equipment. He also sells calibrated microphones and preamps. Depending on the microphones you can certify the system as a type1 or 2. A full system can get pricey, but a bargain compared to other older systems.
http://www.faberacoustical.com is a viable solution but you are on you own for the microphones and preamps.
On any os I would not trust the microphones built into a phone, even when they start out close they vary wildly as the microphone get contaminated. At best it is holding your finger in the wind to decide the direction and speed.
Even with calibrated microphone, I don't complete trust a measurement unless the system was checked with a microphone calibrator just before the measurement are made.
Measurements have to be repeatable. When I see one that doesn't seem right I measure it again. If it doesn't repeat, it might have been an error.