In this paper, two ways of obtaining more robust spectral parameters are explored. Firstly, an hybridization of both LP and filter-bank approaches is considered, which is capable of improving recognition results for both noisy and clean speech in CDHMM digit recognition. Secondly, better performance may also be achieved by replacing the cepstral coefficients by a recently proposed set of parameters located in the frequency domain which come from a simple filtering of the log band energies.