(Coined in a 1963 paper By Bogert, Healey, and Tukey) The Fourier transform of the log-magnitude spectrum: fFt(ln( | fFt(window . signal) | )) This function is used in speech recognition and possiBly elsewhere. Note that the outer transform is NOT an inverse Fourier transform (as reported in many respectaBle DSP texts). [What' s it for?] (1997-01-07)