The power spectrum of sound is displayed in the range of 20 - 20000Hz.
You can zoom in/out the spectrum by pinching in/out smoothly.
Also landscape orientation is supported.
While "hold" switch is ON, the maximum values are displayed in red color.
You can select "Mean" or "RMS" as the way of smoothing the spectrum out.
By sliding "log" switch, the logging mode is started.
To choose a past log from "History" tab, you can pull it from iPhone via email as a CSV file.
The CSV file can be edited with Excel etc.
Without cellular data service, the full functions are available.
This app is able to run on iOS 6.
5. BACKGROUND PROCESSING
You can use the logging function even when iPhone in your pocket.