Research Committee | Current Projects
Forensic comparison of Chinese female voices
Cuiling Zhang1 and Geoffrey Stewart Morrison2
1Department of Criminal Science and Technology, China Criminal Police University, Shenyang, China
2School of Language Studies, Australian National University, Canberra, Australia
Research on forensic voice comparison has primarily focussed on male voices, which is understandable given that most casework deals with male voices; however, in the Principal Applicant's casework experience approximately 20% of cases involve female voices. There is therefore a need to conduct research on the effectiveness of forensic techniques when applied to female voices. The present study examines the effectiveness of forensic voice comparison based on parametric curves fitted to the formant trajectories of some frequently-occurring Chinese diphthongs and triphthongs produced by female speakers. The aims of the research are:
- To collect a database of recordings of Standard-Chinese female voices which can be used for forensic voice comparison research in the present and subsequent projects, and in casework. (The database will be made available to other researchers.)
- To determine which of the following combinations of vowel phonemes, parametric representations of formant trajectories, and likelihood-ratio calculation procedure are the most effective for forensic comparison of Standard-Chinese female voices:
- vowel phonemes: / iao1, uo3, ao4, iou4 /
- parametric representations: polynomials, discrete cosine transformations
- likelihood ratio calculation: multivariate-kernel-density model, Gaussian mixture models
- To determine the number of speakers necessary in the population sample in order to achieve asymptotic behaviour in the likelihood ratios.