This document discusses different ways of visualizing sound, including the oscilloscope, spectrum analyzer, and sonogram. The oscilloscope shows amplitude over time in 2D and is useful for viewing waveforms but not frequency analysis. The spectrum analyzer shows frequency on the x-axis and amplitude on the y-axis, allowing analysis of harmonics, bandwidth, and other spectral components. The sonogram shows frequency on the y-axis, time on the x-axis, and amplitude with color, visualizing how a sound evolves over time. Examples of software for each visualization method are provided.