This paper addresses the problem of bandwidth expansion for the purpose of robust speech recognition. We show that an HMM-based ASR engine trained with full spectrum range data (0-8kHz) can successfully perform speech recognition tasks over band-filtered test data compensated by means of a series of simple MFCC parameter corrector functions. The problem is important when ASR is employed for audio streams of unknown frequency bandwidth common in spoken document retrieval. Evaluation is based on recognition rates. Accuracy varies depending on the width and spectral regions eliminated, but the system shows great advantages over the use of uncompensated filtered test data. The theoretical maximum recognition rates using corrector functions over filtered test data are very close to the base rate (unfiltered data) even when the greatest part of the spectrum of the original data is suppressed. These rates are even better than those obtained in the matched train/test HMMs with filtered data.