Spectrogram Preferences
From Audacity Manual
You can view any audio track as a Spectrogram instead of a Waveform by selecting either "Spectrum" or "Pitch (EAC)" from the Track Drop-Down Menu. Spectrogram Preferences lets you adjust some of the settings for these two views.
FFT Size
- Size: The radio buttons let you choose the size of the Fast Fourier Transform (FFT) which affects how much vertical (frequency) detail you see. Larger FFT sizes give more low frequency resolution and less temporal resolution, and are slower.
- Window type: Determines precisely how the spectrogram is computed. 'Rectangular' is slightly faster than other methods, but introduces some artefacts. All methods give broadly similar results.
Display
- Grayscale: Shows gray shades in the Spectrum view instead of full colors.
- Minimum Frequency: This value will correspond to the bottom of the vertical scale in the spectrogram. Frequencies below this value will not be visible.
- Maximum Frequency: This value corresponds to the top of the vertical scale. The value can be set anywhere between 200 Hz and half the current sample rate of the track (for example, 22050 Hz if its rate is 44100 Hz). For some uses such as speech recognition or pitch extraction, very high frequencies are not visually important, so this allows you to hide these and only focus on the important ones.
