• 말소리와 음성과학
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• 제4권3호
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• pp.95-101
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• 2012

In this paper, we introduce the automatic speaker identification system 'SPO(Supreme Prosecutors Office) Verifier'. SPO Verifier is a GMM(Gaussian mixture model)-UBM(universal background model) based automatic speaker recognition system and has been developed using Korean speakers' utterances. This system uses a channel compensation algorithm to compensate recording device characteristics. The system can give the users the ability to manage reference models with utterances from various environments to get more accurate recognition results. To evaluate the performance of SPO Verifier on Korean speakers, we compared this system with one of the most widely used commercial systems in the forensic field. The results showed that SPO Verifier shows lower EER(equal error rate) than that of the commercial system.

• 대한음성학회지:말소리
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• 제46호
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• pp.25-35
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• 2003

This study deals with the disguised voice (or voice disguise) in the field of forensic phonetics. We especially studied the effects of the methods of disguised voice on the aural decision. Within the nonelectronic-deliberate voice disguise area, the methods of disguised voice include use of lowered pitch, pinched nostrils, falsetto, and whisper. Ten (male:5, female:5) Seoul speakers made a recording of 16 sentences. In the aural test, 30 subjects listened normal and disguised voice. And they were asked to make a decision whether speakers identified or not. The result is as follows: The speaker verification of the falsetto and whisper was more difficult than the lowered pitch and pinched nostrils.

• 말소리와 음성과학
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• 제2권3호
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• pp.135-139
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• 2010

Forensic speaker identification needs high accuracy and reliability. However, the current level of speaker identification does not reach its demand. Therefore, the confidence evaluation of results is one of the issues in forensic speaker identification. In this paper, we propose a new confidence measure of forensic speaker identification system. This is based on pitch differences between the registered utterances of the identified speaker and the test utterance. In the experiments, we evaluate this confidence measure by speech identification tasks on various environments. As the results, the proposed measure can be a good measure indicating if the result is reliable or not.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2002년도 11월 학술대회지
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• pp.77-80
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• 2002

This study proposes phonation type index k as a descriptor of the overall spectral tilt, which is free from the effects of fundamental frequency and vowel quality. The newly proposed phonation type index k presents a simple and single measure of the overall spectral tilt. Phonation type index k can be applied to speech technology. It can also be used in diagnosing patients voice qualities in speech pathology. The distribution of phonation type index k, which is speaker-dependent, may be useful in forensic phonetics and voice recognition as an indicator of speaker identity.

• 말소리와 음성과학
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• 제6권2호
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• pp.21-28
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• 2014

We propose a novel scheme for digital audio authentication of given audio files which are edited by inserting small audio segments from different environmental sources. The purpose of this research is to detect inserted sections from given audio files. We expect that the proposed method will assist human investigators by notifying suspected audio section which considered to be recorded or transmitted on different environments. GMM-UBM and GSV-SVM are applied for modeling the dominant environment of a given audio file. Four kinds of likelihood ratio based scores and SVM score are used to measure the likelihood for a dominant environment model. We also use an ensemble score which is a combination of the aforementioned five kinds of scores. In the experimental results, the proposed method shows the lowest average equal error rate when we use the ensemble score. Even when dominant environments were unknown, the proposed method gives a similar accuracy.

• 말소리와 음성과학
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• 제14권3호
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• pp.103-112
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• 2022

스마트폰의 대중화로 인하여 근래 범죄의 증거자료로 제출되는 녹취 파일은 대부분 스마트폰을 통하여 생산되고 있으며, 스마트폰을 기반으로 한 녹음 파일의 무결성(위변조) 여부가 수사와 재판 과정에서 주요 쟁점으로 떠오르고 있다. 가장 높은 국내 시장 점유율을 가진 삼성 스마트폰은 통화 및 음성 녹음, 그리고 편집이 가능한 자체 음성녹음 편집 어플리케이션이 탑재되어 유통되고 있으며, 자체 어플리케이션을 통한 편집은 외부 어플리케이션을 통한 편집과 다르게 원본 파일과의 유사성이 높기에, 무결성을 입증하기 위해 더 정밀한 분석 기법 개발이 필요하다. 본 연구에서는 삼성 스마트폰 34개 기종에서 생성된 원본 녹음 파일과 자체 제공 음성녹음 편집 어플리케이션을 통한 편집 파일의 메타데이터 구조와 속성을 분석하여, 원본과 편집본 사이의 음성 파일 메타데이터 구조 및 속성 값에서 유의미한 차이가 있음을 확인하였다.