The spectrogram is a visual representation that shows how the spectral density of a signal varies with time. The figure shows frequency on the x-axis and time on the y-axis.
Similar with Spectrum mode, you can also change the scale of the x-axis to logarithmic, linear, or to display note names just by highlight the LOG, LIN or ST buttons. The display can be locked by tapping the “Spectrogram (FFT)”.
MF button is highlighted by default, which means that the display shows frequency from 100Hz-1KHz (aka medium frequency area). You can switch FFT Tuning Unit to show frequencies between 10Hz-10KHz by tapping the MF button again.