From Studio Six Digital:
Real Time Analyzer for iPhone. This is the free version of our popular and highly rated 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. The full version adds Pink Noise generation, graph zooming, dB/frequency cursor, Max/Min bars, noise curve overlays, Save and Recall of 10 graphs, external mic support, overall SPL A&C dB readout, and decay options including slower decay, and peak hold and average modes. *** iPhone mic Frequency Compensation Filter RTA uses a special frequency-compensation filter to flatten the iPhone mic. Make sure you select Internal on the setup page. RTA is designed by the same team that built the Audio Toolbox acoustic analyzer. *** Specifications and Devices The 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. RTA will work on first-generation iPhone, but always use the headset mic, as the built-in mic runs at a low sample rate. If you have an iPod Touch 2nd generation, use a headset mic, and if you have a first generation iPod Touch, you must use one of the dock-connector microphones and be running OS 2.2 or later.
What's new in this version:
** Improved microphone compensation filters ** Sped up response of graph display ** Bug fixes