From Studio Six Digital:
Real Time Analyzer for iPhone.Now you can have an accurate and powerful Real Time Analyzer (RTA) for free on your iPhone or iPod touch.This is the free ad-supported version of our popular and highly rated Studio Six Digital RTA app. It includes octave and 1/3 octave modes and iPhone mic compensation.Using ANSI type 1 or better filters, this RTA is very accurate, even in this lite version, since it uses the engine from our full version. Use it to check your sound system, monitor audio, and adjust your car audio system.Try this out, and if you like it you can always upgrade to our full RTA version, or to AudioTools, which includes the full RTA and a lot more. Check out iAudioInterface, our professional-audio test and measurement microphone, line input, and line output accessory made for iPod touch.New! iTestMic is a direct plug-in test & measurement mic that has full pro specs. The full version of RTA, and the version in AudioTools, is ad-free and adds Pink Noise generation, graph zooming, dB/frequency cursor, Max/Min bars, noise curve overlays, Save and Recall of graphs, external mic support, overall SPL A&C dB readout, and decay options including slower decay, and peak hold and average modes, and lots more.*** iPhone mic Frequency Compensation FilterRTA uses a special frequency-compensation filter to flatten the iPhone mic. RTA is designed by the same team that built the Audio Toolbox acoustic analyzer.*** Specifications and DevicesThe internal iPhone mic has a noise floor near 30 dB, and clips around 105 dB. So, be aware that this tool will NOT work in very loud environments, such as clubs or some concerts.