The present study confirmed the intelligibility improvement benefit of clear speech by investigating the intelligibility of Korean stops produced in different speaking styles: conversational, citation-form, and clear speech. This finding supports the Hypo- & Hyper-speech theory that speakers adjust vocal effort to accommodate hearers' speech perception difficulty. A progressive intelligibility improvement was found for the three speaking styles investigated: clear speech was more intelligible than citation-form speech citation-form speech was more intelligible than conversational speech and clear speech was also more intelligible than conversational speech. These findings suggest that the manipulations to elicit three distinct speaking styles in a laboratory setting were successful. Korean lenis stops showed the least intelligibility improvement among the three Korean stop types, and this result suggests that lenis stops should be more resistant to intelligibility enhancement efforts in clear speech than aspirated and fortis stops.

The purpose of this study was to examine the prosody characteristics of sentence-level utterances which contain homographs with context cues in patients with neurogenic communication disorders. Homographs which may be affected by prosody, especially tonic length features, were used to investigate this matter. The characteristics of tone, duration, pitch, and pitch peak were analyzed to examine the characteristics of prosody in patients with lesions in the left or right hemisphere and normal controls. The whole process was recorded using Praat 4.3.14 and for statistical analyses, three-way ANOVA and multiple comparative analyses, Chi-Square tests, and a one-way ANOVA were carried out using SPSS 12.0 for Windows. The conclusions of this study are as follows. First, the length of syllables and vowels in homographs in Korean was different depending on the meaning and was not significant between groups. Second, it was found that patients with lesions in the right hemisphere had significant difference on pitch. Third, it was found that frequency of pitch peak and tone in 'short' tone syllables were different between groups. The conclusion of this study found that the prosody of homographs between groups absolutely was not differentiated. Accordingly, more detailed studies of acoustic parameters and other parameters which the prosody characteristic between groups could be found are needed in the future.

This study aimed at discovering whether Korean language learners who had never been exposed to Korean phones before could distinguish Korean phones and whether learners who had comparatively better ability of identifying phonetic differences displayed a better result in acquiring Korean phonemes. The study conducted two experiments on 25 learners. In Experiment I, an oddball test (ABX) was performed to investigate the learners' ability to discriminate Korean phones on the first day of the course. In Experiment II, an identification test was administered to analyze the ability of identifying Korean phones on the same learners after three weeks of language instruction. The results revealed that the true-beginner learners demonstrated different phonetic discrimination abilities, but these abilities did not seem to correlate with the rate of acquisition.

This study investigates the effect of pitch range reset in Korean listeners' processing of syntactically ambiguous participle structures. Unlike Japanese and English,in Korean, the downtrend or the reset of pitch range does not consistently differentiate Accentual Phrases (AP), a lower level of phrasing, from Intonational Phrases (IP), a higher level of phrasing. Therefore, we explore Korean listeners' comprehension patterns for syntactically ambiguous speech strings varying in 1) the relative height of F0 peaks across prosodic units, and 2) the types of prosodic phrasing, to see whether pitch range reset informs the recovery of syntactic structure even though it is not reflected in the intonational hierarchy in Korean. The results show that the hierarchical level of prosodic phrasing affects the parsing pattern of syntactic ambiguity. The pitch range reset also cued the location of syntactic boundaries, but this effect was confined to phrases across AP.

The current study exploresacoustic variation induced by prosodic contexts in different speech styles,with a focus on motherese or child-directed speech (CDS). The patterns of variation in the acoustic expression of voicing contrast in English stops, and the role of prosodic factors in governing such variation are investigated in CDS. Prosody-induced acoustic strengthening reported from adult-directed speech (ADS)is examined in the speech data directed to infants at the one-word stage. The target consonants are collected from Utterance-initial and -medial positions, with or without focal accent. Overall, CDS shows that the prosodic prominence of constituents under focal accent conditions variesin the acoustic correlates of the stop laryngeal contrasts. The initial position is not found with enhanced acoustic values in the current study, which is similar to the finding from ADS (Choi, 2006 Cole et al, 2007). Individualized statistical results, however, indicate that the effect of accent on acoustic measures is not very robust, compared to the effect of accent in ADS. Enhanced distinctiveness under focal accent is observed from the limited subjects' acoustic measures in CDS. The results indicate dissimilar strategies to mark prosodic structures in different speech styles as well as the consistent prosodic effect across speech styles. The stylistic variation is discussed in relation to the listener under linguistic development in CDS.

This study investigates the perception and production of English front vowels focusing on the distinction in /i/ vs /I/ and /$\varepsilon$/ vs /$\ae$/ by sixty-one Korean speakers. The first portion of this study focused on the perceptional discrimination by the subjects of two sets of English vowel contrasts, /i/ vs /I/ and /$\varepsilon$/ vs /$\ae$/. In the second portion of the study, the production of these vowels by the same subjects who had participated in the perceptional discrimination test was examined acoustically and subsequently compared with that of the control group comprised of native English speakers. The major results indicate that: (1) In perception tests, Korean subjects can discriminate between /i/ and /I/ relatively well, while many of them were not able to discriminate between /$\varepsilon$/ and /$\ae$/; (2) the Korean subjects, however, have difficulty producing a distinct version of these front vowels; and, (3) The relationship between the perception and production is not significant. These results were analyzed with the concept of "under-differentiation" and "reinterpretation of distinction," as well as how phonetic differences influenced the production and discrimination of front vowels by Korean speakers.

This study addresses the issue of whether Korean(L1)-English(L2) non-proficient bilinguals are affected by the native coda-neutralization process when recognizing words in English continuous speech. Korean phonological rules require that if liaison occurs between 'words', then coda-neutralization process must come before the liaison process, which results in liaison-consonants being coda-neutralized ones such as /b/, /d/, or /g/, rather than non-neutralized ones like /p/, /t/, /k/, /$t{\int}$/, /$d_{\Im}$/, or /s/. Consequently, if Korean listeners apply their native coda-neutralization rules to English speech input, word detection will be easier when coda-neutralized consonants precede target words than when non-neutralized ones do. Word-spotting and word-monitoring tasks were used in Experiment 1 and 2, respectively. In both experiments, listeners detected words faster and more accurately when vowel-initial target words were preceded by coda-neutralized consonants than when preceded by coda non-neutralized ones. The results show that Korean listeners exploit their native phonological process when processing English, irrespective of whether the native process is appropriate or not.

The PESQ is an objective speech quality evaluation measure that is known to have a high correlation with a subjective speech quality measure such as MOS. To examine whether it could be useful as an objective quality measure of synthetic speech, we carried out both subjective evaluation tests with MOS and DMOS and an objective evaluation test with PESQ for HMM-based Korean synthetic speech signals and analyzed the correlation between them. Experimental results have shown that the PESQ has correlations of 0.87 with MOS and 0.92 with DMOS. It means that the PESQ holds much promise for evaluating the quality of synthetic Korean speech.

This paper proposes an efficient feature vector processing technique to guard the Speech Emotion Recognition (SER) system against a variety of noises. In the proposed approach, emotional feature vectors are extracted from speech processed by comb filtering. Then, these extracts are used in a robust model construction based on feature vector classification. We modify conventional comb filtering by using speech presence probability to minimize drawbacks due to incorrect pitch estimation under background noise conditions. The modified comb filtering can correctly enhance the harmonics, which is an important factor used in SER. Feature vector classification technique categorizes feature vectors into either discriminative vectors or non-discriminative vectors based on a log-likelihood criterion. This method can successfully select the discriminative vectors while preserving correct emotional characteristics. Thus, robust emotion models can be constructed by only using such discriminative vectors. On SER experiment using an emotional speech corpus contaminated by various noises, our approach exhibited superior performance to the baseline system.

In this paper, we address issues associated with mixed-lingual text-to-speech based on context-dependent HMMs, where there are multiple sets of HMMs corresponding to each individual language. In particular, we propose smoothing techniques of synthesis parameters at the boundaries between different languages to obtain more natural quality of speech. In other words, mel-frequency cepstral coefficients (MFCCs) at the language boundaries are smoothed by applying several linear and nonlinear approximation techniques. It is shown from an informal listening test that synthesized speech smoothed by a modified version of linear least square approximation (MLLSA) and a quadratic interpolation (QI) method is preferred than that without using any smoothing technique.

This study attempted to review the recent, high-quality evidence-based practical research related to the treatment effectiveness of voice disorders which focus on randomized controlled trials (RCTs) and translational research of vocal fold tissue engineering for vocal fold regeneration. Methodology including PICO (P; Populations or Patients, I; Interventions, C; Comparison group (control, placebo, gold standard), O; Outcomes or measures made) information for RCTs and animal models (species), regenerative therapy method, and outcomes of translational research for clinical application was summarized and discussed for future voice disorder research.

In this paper, we investigate the acoustic characteristics of sustained voices from normal subjects and patients with laryngeal pathologies. Perturbation methods (including jitter and shimmer), signal-to-noise ratio (SNR), and nonlinear dynamic methods (such as correlation dimension) are used to analyze normal and pathological voices. We find that jitter does not statistically discriminate between normal and pathological voices, but a significant difference is found for shimmer, SNR, and correlation dimension. The results suggest that nonlinear dynamic analysis may be valuable for the analysis of normal and pathological voices but perturbation analysis should be applied with caution for pathological voice analysis.

The purpose of this study was to compare the characteristics of nasalance in speakers with spastic cerebral palsy (CP) according to the types of sentence used for nasalance test. Twenty-eight speakers with spastic CP participated in this study. The experiment was conducted by analyzing nasalance of prolonged vowel utterance using the Sea sentence, the Zoo sentence, and the Mother sentence. The three sentences differ in the ratio of nasal consonants. The results show significant differences among the types of sentence for nasalance test.

The purpose of the present study was to examine the relationship between sentence repetition and sentence production in school-age children. The participants included 120 school-age children through 1st to 6th grades who were then divided into three grade groups (lower grade: 1st to 2nd grades, intermediate grade: 3th to 4th grades, and higher grade: 5th to 6th grades). The repetition task consisted of 32 sentences that were classified by sentence length (5, 6, 7, and 8 words) and structure (conjunctive and embedded sentences). The sentence production task utilized Lee's (2007) grammaticality judgement and sentence combining task. The findings of present study were as follows. (1) The higher grade performed significantly better than the lower and intermediate grades. (2) The participants performed significantly worse when imitating longer sentences than when imitating shorter ones. In addition, there were interaction effects between grade groups and sentences length. (3) The participants performed significantly better when imitating conjunctive rather than embedded sentences. (4) There was significantly positive correlation between the sentence repetition and sentence production task.

This study investigates the differences in mean F0, intensity, jitter, and shimmer across hearing aid, gender, and vowels. For this study, 18 hearing-impaired children, 18 cochlear implanted children, and 18 normal hearing children as a control group were asked to read seven Korean vowels (/$\alpha$, $\wedge$, o, u, w, i, $\varepsilon$/). Subjects' readings were recorded by NasalView and analyzed by Praat. Results showed that the means of F0 were significantly higher in the hearing impaired group than in the normal hearing group; in the female group than in the male group; and in high vowels than in low vowels. Second, intensity was significantly higher in the hearing impaired group than in the normal hearing group; in the female group than in the male group; and in low vowels than in high vowels. Third, jitter was significantly higher in the normal hearing group than in the hearing impaired group; in the female group than in the male group; and in back vowels than in front vowels. Finally, shimmer was significantly higher in the CI group than in the normal hearing group or the hearing aided group; in the male group than in the female group; and in low vowels than in high vowels.