Audio Tool is described as 'SPL (deciBel) Meter featuring RT60, Leq, Sone, Spectrum Analyzer, Spectrogram, Chart Recorder, Signal Generator, Polarity Checker, and Mic calibration' and is an app in the Audio & Music category. There are six alternatives to Audio Tool for Android, iPhone, Android Tablet, iPad and Windows. The best alternative is AudioTools. It's not free, so if you're looking for a free alternative, you could try Sound Meter or Sound Meter by Splend Apps. Other great apps like Audio Tool are Sound Level Meter (Freemium), Decibel X (Freemium) and Digital Level Meter (Free).
Decibel X is one of very few noise meter apps with highly reliable, pre-calibrated measurements and supports dB468, dBA, dBC. It turns your mobile device into a professional sound level meter, precisely measures the sound pressure level (SPL) all around you.