"Messon" stands for measurement of sound. Main purpose of this application is to connect your iPhone or iPod Touch (2nd gen) to your HiFi system and measure the frequency response of the loudspeakers. If you are looking for a less specific audio application, please consider these ones: SPLnFFT, logSPL, Diapasion Audio Generator.

Basically this application is a sound generator: white noise, pink noise, narrow band noise (exclusive feature !) and sine wave can be selected as source.
This application is also a soundmeter.
Both "source" and "soundmeter" are very easy to use: choose left and/or right speaker to play selected source and click on the record button to monitor input.
Process of measurement is more complex but can be made automatic: choose one of the sources (except pink noise), choose left or right speaker, check auto mode (button located in 'Measurement') and launch recording (the microphone in 'Soundmeter'). Results will be available after few minutes of computing. You can export results by mail for a cut and paste in standard office tools. In this mail you will find as well a copy - in fact an upsized version - of the measurement pictures.
How it works:
* with white noise, an averaged real time FFT is computed on the fly and is displayed with no delay. Once record button is cleared, a Fourier transform is computed for low frequencies because FFT lacks precision there. This later operation takes several minutes. Benefit of using white noise: recording can last as low as 5 seconds
* with narrow band or pure tone: a signal of a given frequency or narrow band is played and after 5 seconds the averaged sound level is read and send to graphics. Then next frequency. This is a very accurate method but recording lasts several minutes
Here are the limitations:
* this application is limited by the quality of the embedded hardware (linearity of the microphone). Best results will be obtained using an external microphone
* you need third party material to calibrate the soundmeter if you want more precision (not needed for speaker measurement as what we measure is relative and not absolute)
This App was seriously designed for my own needs: I am a signal processing expert.
For example, narrow band sound types were validated with Matlab.
If you just need an audio generator, try this App: "Diapason Audio Generator".
If you just need a soundmeter, try this one: "SPLnFFT Noise Meter".

There are more details on this App on my website: follow the link below. In particular the measurement feature is described step by step.

Any comment, any feedback ? There is a blog for this.