Evidential value of voice quality acoustics in forensic voice comparison
Project summary
Forensic voice comparison typically involves comparing a known voice of a suspect with an unknown voice of an offender. This process is crucial in cases involving speech recordings, such as hoax calls, ransom demands, threatening messages, or conversations with accomplices. In legal cases where speech recordings are involved (e.g. hoax calls, ransom demands, threatening voice message, conversation with an accomplice), the comparison of voices may assist the trier-of-fact (e.g. judge/jury) or investigating authorities (e.g. police) in determining whether the two voices originate from the same speaker or different speakers.
A key objective of forensic voice comparison research is to identify speech features that are useful for distinguishing voices. Voice quality (VQ) features (e.g. breathy/creaky/hoarse/nasalised voice) have been considered among the most useful for speaker comparison. However, VQ is typically assessed by experts through subjective auditory analysis and categorized qualitatively. This project was among the first to evaluate the evidential strength of VQ acoustics, marking an important step towards transforming the categorical auditory assessment of VQ features into quantitative analysis which fosters transparency and replicability. Analysis using the Bayesian likelihood ratio framework shows that, contrary to the widely held belief in the utility of VQ analysis, acoustic VQ parameters offer limited speaker-discriminatory value, especially when both speech style mismatch and non-contemporaneous recordings were involved.
Funding
- Early Career Scheme, Hong Kong Research Grants Council. (PI: Ricky Chan, HKD450,000)
Outputs
- Chan, R. (2023). Evidential Value of Voice Quality Acoustics in Forensic Voice Comparison. Forensic Science International, 348, 111725.
- Chan, R. (2023). Speaker discriminatory power of voice quality acoustics under forensic conditions. Proceedings of the 20th International Congress of Phonetic Sciences. Prague, Czech Republic.
Implicit/incidental learning of lexical stress rules
Project summary
This project focuses on implicit/incidental learning, a domain-general process posited as a key mechanism in both first and second language acquisition. A long-standing puzzle in language acquisition research concerns the differential success between first language (L1) and second language (L2) acquisition. While nativists attribute this difference to varying degrees of access to universal grammar, a recent proposal by empiricists suggest that children primarily acquire their first language through implicit learning whereas adults rely more on explicit learning. It is largely our implicit linguistic knowledge that underpins fluency and automaticity in language use. The crux of the problem, then, lies in understanding the scope and limitations of implicit learning in second language acquisition and determining how implicit knowledge can be effectively assessed. Through systematically controlled experiments, this project has demonstrated that implicit knowledge of L2 stress patterns can develop after only brief and incidental exposure. The project also showcased the combined use of subjective and objective awareness measures based on different theories of consciousness.
Funding
- Postgraduate Studentship, University of Hong Kong. (Ricky Chan, HKD 320,400)
Outputs
- Chan, R. & Leung, J. (2018). Implicit knowledge of L2 lexical stress rules: Evidence from the combined use of subjective and objective awareness measures. Applied Psycholinguistics, 39(1), 37-66.
- Chan, R. & Leung, J. (2014). Implicit learning of L2 word stress regularities. Second Language Research, 30(4), 463-484.
- Chan, R. & Leung, J. (2012). Implicit learning of L2 word stress rules. In Miyake, N., Peebles, D. & Cooper, R. P. (Eds.), Proceedings of the 34th Annual Meeting of the Cognitive Science Society. Austin, TX: Cognitive Science Society.
Implicit learning of form-meaning connections and its limits
Project summary
The phenomenon of implicit learning has sparked considerable debate in cognitive psychology over the past few decades. Some psychologists, such as Reber (1993), have characterized it as the primary form of learning, while others, like Lovibond and Shanks (2002), deny the possibility of learning even simple contingencies without awareness. Within the language domain, Gupta and Dell (1999) and Ellis (2000) argue that the acquisition of meaning in language learning necessitates explicit and conscious processes. Conversely, Williams (2003, 2004, 2005) presents evidence supporting the learning of form-meaning connections without awareness, with this learning being influenced by the participants’ existing linguistic knowledge. This project explores the potential for implicit learning of form-meaning connections and examines the conditions under which such learning may occur. A series of experiments reveal that while implicit learning of form-meaning connections is possible, it is constrained by the nature of the meanings involved and the learners’ prior linguistic knowledge.
Funding
- The Economic and Social Research Council (ESRC) and the Research Grants Council of Hong Kong (RGC) Joint Research Scheme (Code: RES-000-22-3030) (PI: Janny Leung, HKD 350,000)
Outputs
- Leung, J. & Williams, J. (2014) Cross-linguistic differences in implicit language learning. Studies in Second Language Acquisition 36(4): 733-755.
- Leung, J. & Williams, J. (2012) Constraints on implicit learning of grammatical form-meaning connections. Language Learning, 62(2): 634-662.
- Leung, J. & Williams, J. (2011) The implicit learning of mappings between forms and contextually-derived meanings. Studies in Second Language Acquisition, 33(1): 33-55.
- Leung, J. & Williams, J. (2006) Implicit learning of form-meaning connections. In R. Sun and N. Miyake (eds.), Proceedings of the Annual Meeting of the Cognitive Science Society, 465-70. Mahwah, N.J.: Lawrence Erlbaum.