Understanding spectrograms

A spectrogram is a time-varying spectral representation that shows how the spectral density of a signal varies with time.

A spectrogram represents a spectrum of frequencies of the sound or other signal in a visual manner. It is used in various science fields, from sound fingerprinting such as voice recognition, to radar engineering and seismology.

Usually, a spectrogram layout is as follows: the x axis represents time, the y axis represents frequency, and the third dimension is the amplitude of a frequency-time pair, which is color coded. This is three-dimensional data; therefore, we can also create 3D plots where the intensity is represented as the height on the z axis. The problem with 3D charts is that humans are bad at understanding and comparing them. Also, they tend to take more space than 2D charts.

Getting ready

For serious signal processing, we would go into low-level details to be able to detect patterns and autofingerprint certain specifics; but for this...