• Proceedings of the KSPS conference
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• 2003.05a
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• pp.163-167
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• 2003

Intonation as suprasegmental phonetic features conveys meanings on the postlexical or utterance level in a linguistically structured way. It includes three aspects: tunes, relative prominence, and intonational phrasing. In this article, I will treat how prosodic phrasing is functionally related to the listening comprehension of English by analysing the students' errors of listening comprehension. When utterance meaning is conveyed, it is realized to be divided into intonational phrases. The small intonational phrase is regarded as an intermediate phrase which has a primary accent and a phrase tone or audible break. Most students' errors of listening occurred with linking pronunciation in the intermediate phrases of the fast speech. Thus through the smallest unit with tune we can help students improve their pronunciation and listening ability of English.

• Proceedings of the KSPS conference
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• 2005.11a
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• pp.189-192
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• 2005

This study investigates the asymmetry effect between acoustics and perception. The examined cues are closure duration, closure voicing, VOT, release, pre-vowel duration, post-vowel duration. Five native speakers of English and 30 Korean college students participated in the present study. The results showed that high level Korean English learners parallels native speakers in their responses, while mid and low level Korean learners are substantially different from natives.

• The Journal of the Acoustical Society of Korea
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• v.18 no.6
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• pp.49-56
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• 1999

In many continuous speech recognition systems based on HMMs, decision tree-based state tying has been used for not only improving the robustness and accuracy of context dependent acoustic modeling but also synthesizing unseen models. To construct the phonetic decision tree, standard method performs one-level pruning using just single Gaussian triphone models. In this paper, two novel approaches, two-level decision tree and multi-mixture decision tree, are proposed to get better performance through more accurate acoustic modeling. Two-level decision tree performs two level pruning for the state tying and the mixture weight tying. Using the second level, the tied states can have different mixture weights based on the similarities in their phonetic contexts. In the second approach, phonetic decision tree continues to be updated with training sequence, mixture splitting and re-estimation. Multi-mixture Gaussian as well as single Gaussian models are used to construct the multi-mixture decision tree. Continuous speech recognition experiment using these approaches on BN-96 and WSJ5k data showed a reduction in word error rate comparing to the standard decision tree based system given similar number of tied states.

• MALSORI
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• no.51
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• pp.71-84
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• 2004

In this paper, we propose the automatic speech database verification method(or called automatic verification) based on confidence measure for a large speech database. This method verifies the consistency between given transcription and speech using the confidence measure. The automatic verification process consists of two stages : the word-level likelihood computation stage and multi-level likelihood ratio computation stage. In the word-level likelihood computation stage, we calculate the word-level likelihood using the viterbi decoding algorithm and make the segment information. In the multi-level likelihood ratio computation stage, we calculate the word-level and the phone-level likelihood ratio based on confidence measure with anti-phone model. By automatic verification, we have achieved about 61% error reduction. And also we can reduce the verification time from 1 month in manual to 1-2 days in automatic.

• Proceedings of the KSPS conference
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• 2002.11a
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• pp.86-89
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• 2002

According to Pierrehumbert (1980), two level tones - H and L - are enough in representing intonation of intonational languages. But in Korean, high fall and low fall boundary tones, both of which must be represented as HL％ in intonational phonology as in Jun (1993, 1999), are distinct not only acoustically but also functionally. The same is true in the case of high level and mid level boundary tones, which must be represented as H％ in intonational phonology. In this paper, I conducted two identification tests to provide crucial evidence that H and L are not enough in intonational phonology. The results of the identification tests show that categorical perception occur between high level and low level as well as between high fall and low fall. Based on this fact and the results of the acoustic analyses in Lee (1999, 2000), I strongly propose to adopt one more level tone - M - to represent Korean boundary tones.

• Proceedings of the KSPS conference
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• 2007.05a
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• pp.173-175
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• 2007

The lexical decision task (LDT) commonly postulates the activation of semantic level. However, there are few studies for the feedback effect from semantic level. The purpose of the present study is to investigate whether the feedback effect from semantic level is facilitatory or inhibitory in Korean LDT. In Experiment 1, we manipulated the number of phonological syllable neighbors (PSN) and the number of semantic neighbors (SEN) orthogonally while orthographic syllable neighbor (OSN) is dense. In the results, the significant facilitatory effect was shown in words with many SEN. In Experiment 2, we examined same conditions as Experiment 1 but OSN was sparse. Although the similar lexical decision latency pattern was shown, there was no statistical significance. These results can be explained by the feedback activation from semantic level. If a target has many SENs and many PSNs, it receives more feedback activation from semantic level than a target with few SENs and PSNs.

• MALSORI
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• no.52
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• pp.49-60
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• 2004

The purpose of this paper was to evaluate the effect of hearing level on fundamental frequencies in children. Participants totaled sixty children divided by three groups: congenitally deafened children with cochlear implantation(CI), congenitally deafened children with hearing aids(HA), and children with normal hearing(NH). Fundamental frequencies were measured during the sustained phonation of a vowel /a/. There was statistically significant difference of fundamental frequencies across the groups(p<.01). In post hoc analysis, HA and NH group showed statistically significant difference, but CI group didn't showed significant differences with two groups. In correlation analysis between F0 and the chronological age, there were significant negative tendencies in CI and NH group, but not in HA group. The characteristics of fundamental frequency in CI group were found similar to NH group than HA group in this study. Therefore the results of this study suggest that the hearing level is one of the influencing factors to the fundamental frequency of children.

• MALSORI
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• no.59
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• pp.69-87
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• 2006

Among the conventional time-scale modification (TSM) methods, the synchronized overlap and add (SOLA) method is widely used due to its good performance relative to computational complexity But the SOLA method remains complex due to its synchronization procedure using the normalized cross-correlation function. In this paper, we introduce a computationally efficient SOLA method utilizing 3 level center clipping method, as well as zero-crossing and level-crossing information. The result of subjective preference test indicates that the proposed method can reduce the computational complexity by over 80% compared with the conventional SOLA method without serious degradation of synthesized speech quality.

• Proceedings of the KSPS conference
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• 2000.07a
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• pp.255-270
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• 2000

Because the accuracy is essential, in order to get the fluency in speaking, both of them are very important in English education and in-service training programs. To get the accuracy and the fluency, the causes and phenomena of the unnatural pronunciation have to be surveyed first of all. Therefore, this article surveyed the problematic and unnatural pronunciation of Korean English teachers in elementary and secondary schools using CSL and Multi-speech. And also, tried to pinpoint what the causes of unnatural pronunciation are\ulcorner Next a procedure or steps were offered for them to speak naturally through in-service training programs. Through this analysis, it was found that elementary teachers have unnatural pronunciation below, within and beyond word level, and the secondary teacher has unnatural pronunciation within and beyond word level. Therefore, pronunciation training courses have to put emphasis on segment features first, and move to suprasegmental features for elementary teachers. For secondary teachers, pronunciation training courses have to focus on word level and move to suprasegmental features, in other words beyond word level. And these pronunciation training courses have to be run integrated.

• Journal of KIISE:Software and Applications
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• v.26 no.10
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• pp.1237-1246
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• 1999

최근 모든 분야에서 외국과의 교류가 증대됨에 따라서 한국어 문서에는 점점 더 많은 외국어 음차 표기가 사용되는 경향이 있다. 하지만 같은 외국어에 대한 음차 표기에 개인차가 심하여 이들 음차 표기를 포함한 문서들에 대한 검색을 어렵게 만드는 원인이 되고 있다. 한 가지 해결 방법은 색인 시에 같은 외국어에서 온 음차 표기들을 등가부류로 묶어서 색인해 놓았다가 질의 시에 확장하는 방법이다. 본 논문에서는 외국어 음차 표기들의 등가부류를 만드는데 필요한 음차 표기의 음성적 유사도 비교 알고리즘인 Kodex를 제안한다. Kodex 방법은 기존의 스트링 비교 방법인 비음성적 방법에 비해 음차 표기들을 등가부류로 클러스터링하는데 있어 더 나은 성능을 보이면서도, 계산이 간단하여 훨씬 효율적으로 구현될 수 있는 장점이 있다.Abstract With the advent of digital communication technologies, as Koreans communicate with foreigners more frequently, more foreign word transliterations are being used in Korean documents more than ever before. The transliterations of foreign words are very various among individuals. This makes text retrieval tasks about these documents very difficult. In this paper we propose a new method, called Kodex, of measuring the phonetic similarity among foreign word transliterations. Kodex can be used to generate the equivalence classes of the transliterations while indexing and conflate the equivalent transliterations at the querying stage. We show that Kodex gives higher precision at the similar recall level and is more efficient in computation than non-phonetic methods based on string similarity measure.