Speech recognition errors affect the performance of multimodal systems especially in noisy conditions. For that reason the use of speech recognition confidence score and time stamps is suggested. This paper deals with the impact of a signal enhancement method on these speech recognition’s parameters, in the presence of noise. By recognising noisy signals not only the word error rate (WER) increases but also the word-based confidence scores decline. Therefore, the role of speech recognition in multimodal systems weakens. The experimentation involves input signal corrupted by coloured noise with varying Signal-to-Noise Ratio. A non-linear spectral subtraction method (NSS) will be used in conjunction with the Continuous Speech Recognition system developed for the ERMIS project (IST-2000-29319) to quantify the impact of speech enhancement on speech recognition output.