Vibration signals are usually affected by noise, which is in turn related to the measurement and data processing procedures. This paper presents a new subband adaptive denoising method for detective impulsive signatures based on minimum description length principle with improved normalized maximum likelihood density model. The threshold of the proposed denoising method is determined automatically without the need to estimate the noise variance. The effectiveness of the proposed denoising method over VisuaShrink, BayesShrink and minimum description length denoising methods are given through simulation and practical applications.