Cepstrum
A representation obtained by transforming the logarithm of a signal spectrum, useful for separating source and filter characteristics and analyzing periodic structure.
Signal Processing Context
The cepstrum is obtained by transforming the logarithm of a spectrum and is useful for separating slowly varying spectral-envelope information from faster periodic structure. Speech processing uses this idea to represent vocal-tract characteristics more compactly.
Conceptual Boundary
A cepstrum is not an ordinary time-domain waveform and should not be interpreted as a second spectrum with the same physical frequency axis. Its independent variable is commonly expressed as quefrency.