Oscilloscope vs Audio Analyzer

"I use this for analog, and audio measurements. Attach an Apple USB adapter and a $40 stereo A-D converter available online, and my iPad is like a $300 O'Scope." -thymeout- Oscilloscope app is great for analyzing audio range signals, or learning oscilloscope measurement basics. The interface includes many standard oscilloscope controls, such as: triggering, time and voltage per division, signal measurement cursors, and more. The app incorporates a signal (function) generator capable of generating sine, square, triangle, and sawtooth waveforms of up to 22 KHz. Calibration to an external reference signal is supported, guaranteeing the accuracy of measurements. Input can be acquired via the built-in microphone or an external mic/probe connected to the headset connector. For best results, use an external audio interface connected to your device dock. This allows for standard audio equipment to be connected, as well as for dual channel input. Oscilloscope probes also be connected (using a BNC connector). When feeding external signals via probes, you should take care not to exceed 1V AC voltage. Currently iDevices support only AC input. For up-to-date information on feeding signals and currently supported audio interfaces, please visit http://oa.onyx3.com Feature Highlights: ● Real-time waveform display (60 FPS) ● Triggering modes: Normal, Auto, Single ● Set trigger level and pre-trigger time ● Dual channel signal generator ● Reference signal calibration ● Pause function to get a screen capture ● Export traces as text file for further analysis ● Measure signal data using cursors ● Use "finger pinch" on screen to set voltage and time base ● Double tap screen to enter Black Panel mode ● Three color themes to choose from ● XY mode for viewing Lissajous figures ● Frequency range 20Hz-22KHz ● iPhone X ready

The analyzed result of the waveform is rendered at 60FPS.
The following 4 functions can be accessed: Waveform visualizer (oscilloscope) Spectrum analyzer Historical peak Historical FFT Tapping each function enters into full-screen mode and tapping once more exits full-screen mode. Horizontal zoom is only available for the spectrum analyzer.
Magnification gesture (aka pinching) allows for zooming in and out, and frequency offset can be performed by swiping on the screen horizontally. Vertical swiping adjusts input volume.
Coefficients are displayed in the corner. 
*dBFullScale
20 * log10 ( input) A demonstration is here. https://www.youtube.com/watch?v=6mDa_zCgYzE