1. A voice biometrics system adapted to authenticate a user based on speech diagnostics, the voice biometrics system comprising: a pre-processing module configured to receive an input voice sample and pre-process the input voice sample by: a clipping module configured to clip the input voice sample based on a clipping threshold; a voice activity detection module configured to apply a detection model on the input voice sample to determine an audible region and a non-audible region in the input voice sample; and a noise reduction module configured to apply a noise reduction model to remove noise components from the input voice sample; a feature extraction module configured to extract features from the pre-processed input voice sample; and an authentication model configured to authenticate the user by comparing a plurality of features extracted from the pre-processed input voice sample to a plurality of enrolment features, wherein the voice activity detection module further comprises a zero crossing module configured to detect the polarity of the input voice sample across a time.