Spectrogram gray-scale plots show how a sound’s spectrum changes over time

Evidence

The decibel amplitude of the signal is plotted as a gray scale, with black representing high amplitude and white representing low amplitude. This representation is an excellent way of seeing the time evolution of the spectral components of a musical sound. However, it can suffer from the time-smearing effects discussed earlier. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 495

Categorization

• DEFINE: Explains the spectrogram’s core representational convention: amplitude as gray scale, frequency-time axes.