JL Audio Tools is a set of great car audio analysis helpers.

It includes an SPL Meter, RTA, and Speaker Polarity tester. Also, you get four audio calculators designed to help with car audio installation and test.

SPL, RTA, and Polarity are all fully functional tools, and they can all be upgraded to full professional-grade audio test tools.

SPL is a great digital SPL meter, with special microphone compensation built in to correct the iPhone and iPod touch mic, to get the best possible readings. SPL Upgrade adds A and C weighting, octave band weighting, ANSI Slow, Fast, Peak, Impulse, and LEQ modes, and the ability to store readings.

RTA is a 1/3-octave band Real Time Analyzer, including mic compensation to show the flattest possible readings using the iPhone and iPod touch mics. The upgrade adds a cursor, pink noise generation, Octave mode, different decay modes, noise curve overlays, and more.

Polarity lets you check your speaker polarity, using a waveform that you can download at our website. The upgrade adds filters for woofer, midrange, and tweeter, and generates the test signal internally.

Like all sound measurement apps, accuracy varies somewhat between devices, and some models of iPhone and iPod touch don't include mics.

All of these modules were built using the advanced engines from Studio Six Digital.