Speech Quality Enhancement in Digital Forensic Voice Analysis

Part of the Studies in Computational Intelligence book series (SCI, volume 555)

Abstract

The influence of noise and reverberation in Digital Forensic voice evidence can conceal the identification, verification and processing of crime data. Computationally, the efficiency in processing speech signals largely depends on the integrity and authenticity of audio/voice recordings. Our interest is on improving integrity, vis-à-vis the intelligibility of speech signals. We achieved this in four folds. First, a speech quality enhancement technique that cleans and rebuilds defective speech data for quality Forensic analysis is proposed by exploring an optimal estimator for the magnitude spectrum, where the Discrete Fourier Transform (DFT) coefficients of clean speech are modelled by a Laplacian distribution and the noise DFT coefficients are modelled using a Gaussian distribution. Second, an automatic speech pre-processing algorithm for phoneme segmentation of raw speech data, capable of iteratively refining Hidden Markov Model (HMM) speech labels for improved intelligibility is introduced. Third, a simulation of the distortion from a quantised R-bit and computation of the Signal-to-Noise Ratio (SNR) for the signal to quantisation noise is carried out for the purpose of managing speech signal distortions. Fourth, an investigation of the effect of confused phonemic and tone bearing unit features on the intelligibility of speech is presented to assist Forensic experts decode voice disguise or language “barriers” that may impede proper Forensic voice analysis. Results obtained in this investigation reveal a future of prospects in the field of Forensic intelligence and is most likely to reduce unnecessary setbacks during Forensic analysis.

Keywords

Forensic science intelligent system speech quality evaluation speech synthesis voice adaptation 

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Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  1. 1.Department of Computer ScienceUniversity of UyoUyoNigeria
  2. 2.Centre for Speech Technology Research (CSTR)University of EdinburghEdinburghUK

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