App gets audio data from microphone and plots the real time spectrum in the form of a scrolling image.

App settings:

• Sample Rate = the sample rate (in Hz) at which the microphone will be read. Most devices support up to 48 kHz. High-end devices support up to 192 kHz.

• FFT Buffer Size = the size (in samples) of the audio buffer used to compute the FFT. Must be a power of 2, min = 128, max = 16384. Bigger value gives better frequency resolution. Smaller value gives better time resolution.

• Min. Dispalyed Frequency

• Max. Displayed Frequency

• Gain (dB)

• Displayed Time Window (in milliseconds)

• Frequency Grid Step (in Hz) = will draw horizontal division lines

• Time Grid Step (in milliseconds) = will draw vertical division lines moving together with the plot.

Free version limitations:

• sample rate = 8000 Hz (fixed)

• FFT buffer size = 512 (fixed)

Users can upgrade to Premium Version via in-app purchase (one time payment).

Premium version advantages:

• configurable sample rate.

• configurable FFT buffer size: 128, 256, 512, 1024, 2048, 4096, 8192, 16384.

Planned features for future app updates:

• show spectrum of audio file

• export spectrum to file