Acoustical Society of America

Forensic Acoustics Subcommittee

Special Session on Forensic Acoustics

- ICA 2013: 21st International Congress on Acoustics
- 165th Meeting of the Acoustical Society of America
- 52nd Meeting of the Canadian Acoustical Association

Montréal, Québec, 2–7 June 2013

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International Commission for Acoustics ICA 2013 Candian Acoustical Association Candienne d'Acoustique

Distinguishing between science and pseudoscience in forensic acoustics


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Monday 3 June 2013, room 515abc

Invited Presentations

  • A Canadian Perspective on Forensic Science versus Pseudoscience
    1aSCa2, 9:20–9:40 am

    • Brent Ostrum
      Senior Scientific Advisor, Science & Engineering Directorate, Canada Border Services Agency, Ottawa, ON, Canada

      This presentation will provide my personal observations regarding Forensic Science versus Pseudoscience in the Canadian legal system. I am neither a lawyer nor a judge; rather, I am a forensic scientist with over 25 years of experience in the Canadian system. My presentation focuses on relevant criteria for expert evidence considered in Canadian courts. The key ruling in R v Mohan (1994) provides the start of the discussion with subsequent court rulings adding various elements. In Canada, we have had several judicial inquiries, such as the Kaufmann Commission, that can serve to guide experts. Select aspects of the 2009 NAS report “Strengthening Forensic Science in the United States: A Path Forward” will also be referenced. There are some common ‘criteria’ often used by courts in different jurisdictions to assess expert evidence, including Forensic Acoustics. In other words, some basic expectations for all forms of expert evidence can be identified. I will attempt to show how select ‘sciences’ have tried to fulfill those expectations. This will involve some commentary on issues of individual examiner competency, oversight at a system level (eg. accreditation), and the need for proper and adequate method validation.

      Mr Ostrum is a Senior Scientific Advisor in the Canada Border Services Agency’s Science and Engineering Directorate. He has been employed as a forensic scientist for over twenty-five years, and has worked for both the Royal Canadian Mounted Police and the Canada Border Services Agency. Mr Ostrum has given testimony as an expert witness in a number of Canadian jurisdictions including British Columbia, Alberta, Saskatchewan, Manitoba and Ontario. He is a student of logic, statistical inference and evidence evaluation as well as expert testimony in the Canadian legal system (particularly from a practitioner’s point-of-view but applying equally to all forms of expert evidence). Mr Ostrum is the sitting chairman of Document Section in the Canadian Society of Forensic Science. He serves as a member of the Executive Council for St2ar (Skill-Task Training Assessment & Research, Inc); an international non-profit organization that provides training and skill-task testing, as well as support for research in the forensic sciences. Mr Ostrum is also very active in standards and methods development for both forensic document examination and facial identification. Mr Ostrum has lectured on many topics including evidence evaluation, admissibility, and proficiency testing and competency.

    • Voice Stress Analyses: Science and Pseudoscience
      1aSCa3, 10:00–10:20 am

      • Francisco Lacerda
        Professor in Phonetics, Department of Linguistics, Stockholm University, Sweden

        Voice stress analyses could be relevant tools to detect deception in many forensic and security contexts. However, today’s commercial voice-based lie-detectors are not supported by convincing scientific evidence. In addition to the scientific implausibility of their working principles, the experimental evidence invoked by the sellers is either anecdotal or drawn from methodologically flawed experiments. Nevertheless, criminal investigators, authorities and even some academics appear to be persuaded by the ungrounded claims of the aggressive propaganda from sellers of voice stress analysis gadgets, perhaps further enhanced by the portrays of “cutting-edge voice-analysis technology” in the entertainment industry. Clearly, because there is a serious threat to public justice and security if authorities adopt a naïve “open-minded” attitude towards sham lie-detection devices, this presentation will attempt to draw attention to plausibility and validity issues in connection with the claimed working principles of two commercial voice stress analysers. The working principles will be discussed from a phonetics and speech analysis perspective and the processes that may lead naïve observers into interpreting as meaningful the spurious results generated by such commercial devices will be examined. Finally, the scope and limitations of using scientific phonetic analyses of voice to detect deception for forensic purposes will be discussed.

        Prof Lacerda is Head of the Department of Linguistics, Stockholm University. He is professor in Phonetics and has a degree in Electrical Engineering, Telecommunications, and Electronics. He was co-author with Anders Eriksson of “Charlatanry in forensic speech science: A problem to be taken seriously” International Journal of Speech, Language and the Law (2007), a paper which the publisher, Equinox, withdrew from its website when a manufacturer of a “voice stress analyzer”, Nemesysco, threatened to sue them for liable in the courts of England & Wales (legal action was not actually instigated). Prof Lacerda later gave evidence before a committee of the Parliament of the United Kingdom which was considering reform of the liable laws in England & Wales. Prof Lacerda has written numerous articles and given numerous presentations, including a 2012 open lecture at the Royal Swedish Academy of Sciences entitled “Les Liaisons Dangereuses: Is finance research flirting with pseudoscience?”

    • Assessing Acoustic Features in the Speech of Asylum Seekers
      1aSCa4, 10:20–10:40 am

      • Judith Rosenhouse
        Linguistics Unit, Swantech Ltd, Haifa, Israel

        One of the areas of forensic linguistics concerns asylum seekers who speak languages which are foreign to the official language of the country where they apply for asylum. Identifying and verifying their real national background may be difficult if their speech manner reveals non-typical properties of their (real or alleged) native languages. Governments submit such asylum seekers’ speech samples for linguistic analysis on various levels, including phonetic acoustics. This aspect of forensic linguistics raises questions about the scientific merit of such an analysis. Our aim is to examine some of the questions which relate to segmental and supra-segmental features that are analyzed acoustically based on recorded samples of asylum seekers’ (alleged) native language and compared with the same features as known from the literature. We demonstrate such issues by examples from the speech of Arabic-speaking asylum seekers whose native tongue is (supposed to be) some local dialect but the recording includes various foreign features reflecting different dialects or languages. These questions involve sociolinguistic factors that affect individual speakers’ speech production due to a complex and unstable life-history. We suggest that the acoustic methods currently used in speech analysis in this context could be considered pseudo-science in many cases.

        Prof Rosenhouse’s research interests include phonetics, Arabic dialectology, sociolinguistics, bilingualism, multilingualism, and forensic linguistics. She has authored more than 130 papers and 10 books. She was winner of a New Israel Foundation Prize (1989), an International Society of Phonetic Sciences Prize (2004), and has been a recipient of several stipends from the Alexander von Humboldt Foundation. Prof Rosenhouse retired from the Technion – Israel Institute of Technology in 2005, and now works for Swantech Ltd.

    • Analysis Criteria for Forensic Musicology
      1aSCa5, 10:40–11:00 am

      • Durand R Begault, H D Heise, Christopher A Peltier
        Audio Forensic Center, Charles M Salter Associates Inc, San Francisco, CA, USA

        Expert testimony for forensic musicology addresses a broad spectrum of legal issues, including the authentication and differentiation of published compositions and musical recordings, performance rights, and legal determinations regarding copyright infringement. While legal cases involving music and performance infringement date back as far as the 19th century, the field of forensic musicology has no stated methodology by which an objective forensic determination can be made. Expert opinions based merely on subjective impression or resulting from the “golden ear” syndrome are pseudo-scientific and not objectively based. This paper proposes scientific methods and recommendations for analysis based on stated criteria, with the goal of controlling examiner bias. Considerations include analyses of composition, performance, and acoustical features, and factors such as melody, harmony, rhythm, and orchestration; pitch, tone, vibrato, and embellishment; metadata analysis; recording technologies; and digital signal processing, including “effects.” By engaging in a series of structured categorizations, the forensic expert can establish a consistent, replicable, and objectively verifiable means of determining whether or not a recorded piece of music has been misappropriated.

        Dr Begault has a PhD (1987) from University of California San Diego, where he worked on music theory, psychoacoustics, digital signal processing, computer audio, acoustic engineering, and speech sciences. His Forensic work at the Audio Forensic Center, Charles M Salter Associates Inc, San Francisco includes: authentication of audio recordings; analysis of the audibility of speech, alarms, and other sounds; enhancement of speech from noisy recordings; voice identification and elimination; analysis of ear witness testimony; analysis of acoustic recordings of gunshots; patent/intellectual property analyses for audio technology; and music copyright infringement. He is also a Principal Investigator at the NASA Ames Research Center’s Spatial Auditory Display Laboratory, and is an Adjunct Professor in the Sound Recording Area, Department of Music Research, McGill University, Montréal.

    • Panel Discussion
      11:00–11:30 am

    • Lunch Break
      11:30 am 1:30 pm

    Contributed Presentations

    • Mismatched Distances from Speakers to Telephone in a Forensic-Voice-Comparison Case
      1pSCc1, 1:00–1:20 pm

      • Ewald Enzinger
        Forensic Voice Comparison Laboratory, School of Electrical Engineering & Telecommunications, University of New South Wales, Sydney, NSW, Australia

        In a forensic-voice-comparison (FVC) case, one speaker (A) was talking on a mobile telephone, and another (B) was standing a short distance away. Later, B moved closer to the telephone. Shortly thereafter, there was a section of speech where the identity of the speaker was disputed. All material for training an FVC-system could be extracted from this single recording, but there was a near-far mismatch: Training data for A were near, training data for B were far, and the disputed speech was near. We describe a procedure for addressing the degree of validity and reliability of an FVC system under such conditions, prior to it being applied to the casework recording: Sections of recordings of pairs of speakers of known identity are used to train an A and a B model; multiple other sections from each of the A and B recordings are used as test data; a likelihood ratio is calculated for each test section; and system validity and reliability are assessed. Prior to training and testing, the A and B recordings were played through loudspeakers and rerecorded via a mobile-telephone network, B was rerecorded twice, once with the loudspeaker near and once with it far from the telephone.

      • Colleen Kavanagh
        Audio & Video Analysis Unit, Royal Canadian Mounted Police, Ottawa, ON, Canada

        The speaker-specificity of five acoustic features of British English /m/ was explored from a forensic speaker comparison perspective. Normalised duration, centre of gravity (COG), standard deviation (SD), and frequencies at peak and minimum amplitudes were measured for 30 adult male Standard Southern British English and Leeds English speakers. Spectral measurements were made in each of five frequency bands (0–0.5 kHz, 0.5–1 kHz, 1–2 kHz, 2–3 kHz, and 3–4 kHz) and calculated from a 40-ms window at the midpoint of each token. ANOVAs showed Speaker to be a highly significant factor for all variables. Discriminant analysis (DA) and likelihood ratio (LR) estimation assessed speaker discrimination with individual predictors and combinations thereof. Sample sizes limited the number of predictors in DA to eight; F-ratios were used to select the best predictors for analysis. The COG+SD (bands 1, 3, 4, 5) and Best 8 F-ratios (COG bands 1, 4, 5 + SD 1, 3, 4 + Peak 1, 4) tests achieved 53% and 49% correct classification respectively. The Best 8 F-ratios and COG+SD tests also produced the best LR results, while COG+Peak performed similarly. DA and LR results for all predictor combinations will be presented and the most promising speaker comparison parameters highlighted.

    Organizational Meeting

    • Organizational Meeting of ASA Forensic Acoustics Subcommittee
      4.00–5.00 pm
      • The meeting agenda and draft reports will be distributed to members via the members-only forum.
      • This meeting is only open to members (non-members may attend if specifically invited).


    Session Chairs: