J.P. Todoeschuck and O.G. Jensen (Geophysics, vol.53, no.11, p.1410-14, 1988) recently reported that some reflectivity sequences denoted mu (k), calculated from sonic logs, are not white and have a power spectral density approximately proportional to frequency, which is called a Joseph spectrum. A robustness test is now presented for the case of mu (k) having a Joseph spectrum for the minimum-variance deconvolution (MVD) filter and the maximum-likelihood deconvolution (MLD) algorithm, which were developed based on the whiteness assumption about mu (k). From the simulations performed, it is concluded that the possible Joseph spectrum of mu (k) is not a concern when applying the MVD filter and MLD algorithm towards estimating mu (k) from seismic data. >