[cmehdy]

This does read like a joke, I had never heard of it either and I'm wondering if many people do use this at all..

Operations on cepstra are labelled quefrency analysis (or quefrency alanysis[1]), liftering, or cepstral analysis. It may be pronounced in the two ways given, the second having the advantage of avoiding confusion with kepstrum.

[aswanson]

It's used in speech signal processing & seismic signal analysis.

[ljosifov]

Almost all speech recognizers until this latest crop (of end-to-end DL NN ASR) operated on cepstral coefficients (and their delta-s and delta-delta-s) as their feature vector.