User:Leejordan9/Spectrogram

This is a spectrogram of someone saying the words "nineteenth century". The frequencies are shown getting larger as you go up the left line of the graph, and time is shown on the bottom line going from left to right. The legend on the right shows that the color changes with the volume of the sounds.

A 3D spectrogram: The radio frequency spectrum of a battery charger, shown over time

A spectrogram is a visual way of showing all the frequencies of a signal as it changes with time. When this refers to an sound signal, spectrograms can be called sonographs, sonograms, voiceprints, or voicegrams. When the data is represented in a 3D diagram they can be called waterfall displays.

Spectrograms are used a lot in the fields of music, linguistics, sonar, radar, speech processing, seismology, ornithology, and others. Spectrograms of sounds can be used to identify spoken words using phonetics, and to analyse the noises of various animals.

A spectrogram can be created by using an optical spectrometer, a set of band-pass filters, using the Fourier transform, or by using a wavelet transform (in which case it is sometimes known as a scaleogram or scalogram).

Comparing scaleograms for an audio sample that use two different transforms: the discrete wavelet transform and continuous wavelet transform

A spectrogram is usually depicted as a heat map, which shows the intensity of certain frequencies using colour or brightness.

Format

A common format is a 2D graph: one axis represents time, and the other axis represents frequency. Sometimes a third dimension is added, making it 3D, using the height of the graph to indicate the amplitude of a frequency at a particular time. [[Category:Sound]] [[Category:Science]]