71 Spectrograms

Time-frequency analysis shows up a lot. For speech, when we visualize the evolving frequency composition of sounds, it is called a spectrogram. A spectrogram is a visual representation of the spectrum of frequencies of a signal as it varies with time. When applied to an audio signal, spectrograms are sometimes called sonographs, voiceprints, or voicegrams. Spectrograms are used extensively in the fields of music, linguistics, sonar, radar, speech processing, seismology, and more. Spectrograms of audio can be used to identify spoken words phonetically, and to analyze the various calls of animals. For music, this is the graphic equalizer on a stereo.

On spectrograms (time-frequency plots) of speech, there are bands of power at different frequencies. These are formants. As the speaker changes the sound it is making, the power bands swoop up and down. These are transitions.