AudioTools is described as 'suite of professional-grade audio and acoustic analysis apps. Included in the price of this app is a great collection of professional tools'. There are seven alternatives to AudioTools for a variety of platforms, including Android, Android Tablet, iPad, iPhone and Mac. The best alternative is Audio Tool. It's not free, so if you're looking for a free alternative, you could try Digital Level Meter or Decibel X. Other great apps like AudioTools are Sonic Atom (Paid), Sound Level Meter (Freemium), Sound Meter by Splend Apps (Free) and Sound 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.
You can measure the environmental noise in decibels. Sound Level Meter is the part 4. of Smart Tools series. (noise) Acoustimeter uses your phone mic to measure noise volumn in decibels(dB) and shows a reference. SPL(sound pressure level) noisemeter.