• Phonetics and Speech Sciences
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• v.10 no.2
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• pp.7-14
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• 2018

The paper investigates the acoustic characteristics of English fricatives in the TIMIT corpus, with a special focus on the role of voicing in rendering fricatives in American English. The TIMIT database includes 630 talkers and 2,342 different sentences, and comprises more than five hours of speech. Acoustic analyses are conducted in the domain of spectral and temporal properties by treating gender, voicing, and place of articulation as independent factors. The results of the acoustic analyses revealed that acoustic signals interact in a complex way to signal the gender, place, and voicing of fricatives. Classification experiments using a multiclass support vector machine (SVM) revealed that 78.7% of fricatives are correctly classified. The majority of errors stem from the misclassification of /θ/ as [f] and /ʒ/ as [z]. The average accuracy of gender classification is 78.7%. Most errors result from the classification of female speakers as male speakers. The paper contributes to the understanding of the effects of voicing and gender on fricatives in a large-scale speech corpus.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.11-18
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• 2011

This paper examines the categorical labeling of lexical pitch accent contrasts in North Kyungsang and South Cholla Korean listeners. It focuses specifically on investigating whether the pitch accent perception of adults and children has a dialect-specific effect. To evaluate the development of perceptual identification, slopes, intercepts, and positions at categorical boundaries were computed using a logistic regression function. The results showed that differences in slopes and intercepts were significant between North Kyungsang child and adult listeners, but the same was not the case for the positions at boundaries. As far as South Cholla child and adult listeners were concerned, there was a significant difference in slopes, but not intercepts and positions at boundaries. In the present study, the comparison of intercepts and slopes at the boundaries indicated developmental differences between North Kyungsang adult and child listeners. This improvement in categorical proportion seems to be a result of developmental changes in categorical perception. For South Cholla adult and child listeners, however, perception of the non-native contrast becomes less categorical.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.49-56
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• 2011

This study investigates how American English high back vowels are identified. American English and Korean speakers participated in a phonetic experiment for this study. This study shows their response times of the vowels and discusses how the speakers identified them. For the experiment I used a synthesized vowel continuum between American English /u/ and /$\mho$/based on American English male speakers' voice obtained by Peterson and Barney (1952). I manipulated spectral steps and vowel duration of the stimuli. The statistical results showed that American English speakers were not able to distinguish the stimuli based on spectral quality. Instead they relied on vowel duration. This suggests that the American English high back vowels have changed since Peterson and Barney recorded them in 1952. The Korean speakers also relied on vowel duration, not spectral quality since they could not distinguish them. American speakers' response times of these vowels were not affected by both spectral quality and vowel duration. Koreans' response times were affected by vowel durations only.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.63-68
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• 2011

This study investigates how Korean students employ acoustic-phonetic cues in perceiving word boundaries of near-homophonous English phrases. For this study, 60 Korean college students participated in the experiment of discriminating word boundaries for 42 pairs of stimuli comprising the allophonic cues of aspiration and glottal stop. Results were analysed in terms of the correctness of responses and the correlation between correctness and confidence. Results showed that stimuli pairs of the glottal stop cue give a higher correctness but those of aspiration a relatively lower correctness. Comparison of the results of this study with those of the previous studies of English and Japanese speakers showed that Korean and Japanese speakers of English give a substantially lower correctness than native speakers of English, while Korean learners of English as a foreign language provide a lower correctness than Japanese speakers of English as a second language.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.109-114
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• 2011

To estimate sound direction of arrival with a pair of microphones, a method based on Time Difference of Arrival (TDOA) estimation using the Cross Power Spectrum Phase (CPSP) function is largely used due to its simplicity and good performance. In this paper, we investigate CPSP maximum values for various SNRs and adverse environments, and propose a novel method to improve the estimation performance of sound direction of arrival. The proposed method applies a threshold to the CPSP values and increases the reliability of the estimated sound direction. Through computer simulation for various SNRs, we validate the effectiveness of the proposed method. When the threshold was set to 0.1, more than 90% of success rate of sound direction of arrival estimation has been achieved for directions of $10^{\circ}$, $40^{\circ}$, $70^{\circ}$ from the source location even with reverberation times of 0.1s.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.91-98
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• 2011

In this paper, a multi-channel speech enhancement method using the linearly constrained minimum variance (LCMV) algorithm and a variable learning rate control is proposed. To control the learning rate for adaptive filters of the LCMV algorithm, the direction of arrival (DOA) is measured for each short-time input signal and the likelihood function of the target speech presence is estimated to control the filter learning rate. Using the likelihood measure, the learning rate is increased during the pure noise interval and decreased during the target speech interval. To optimize the parameter of the mapping function between the likelihood value and the corresponding learning rate, an exhaustive search is performed using the Bark's scale distortion (BSD) as the performance index. Experimental results show that the proposed algorithm outperforms the conventional LCMV with fixed learning rate in the BSD by around 1.5 dB.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.99-108
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• 2011

The perturbation parameters like jitter, shimmer, and signal-to-noise ratio (SNR) are largely estimated in the particular segment from the subjective or whole portion of the given pathological voice signal although there are many possible regions to be able to analyze the voice signals. In this paper, the pathological voice signals were classified as type 1, 2, 3, or 4 according to narrow band spectrogram and the value differences of the perturbation parameters extracted in the subjective and entire portion tended to be getting bigger as from type 1 to type 4 signals. Therefore, sample selection method based on moving window to analyze type 2 and 3 signals as well as type 1 signals is proposed. Although type 3 signals cannot be analyzed using the perturbation analysis, the type 3 signals by selecting out the samples in which error count is less than 10 through moving window were analyzed. At present, there is no method to be able to analyze the type 4 signals. Future research will endeavor to determine the best way to evaluate such voices.

• Phonetics and Speech Sciences
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• v.4 no.2
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• pp.121-126
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• 2012

This study deals with how stuttering changes in its frequency in a situation where adult participants who stutter are exposed to one type of background noise, that is, multi-talker babble noise. Eight American English-speaking adults who stutter participated in this study. Each of the subjects read aloud sentences under each of three speaking conditions (i.e., typical solo reading (TSR), typical choral reading (TCR), and multi-talker babble noise reading (BNR)). Speech fluency was computed based on a percentage of syllables stuttered (%SS) and speaking rate was also assessed to examine if there was significant change in rates as a measure of vocal change under each of the speaking conditions. The study found that participants read more fluently both during BNR and during TCR than during TSR. The study also found that participants did not show significant changes in speaking rate across the three speaking conditions. Some discussion was provided in relation to the effect of multi-talker babble noise on the frequency of stuttering and its further speculation.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.173-179
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• 2011

The present study was performed to investigate the intelligibility of voice disorder patients by providing the various background noise levels. Four sets of 12-sentence-stimuli produced by 11 voice disorder patients were prepared, and 5 minute-news from radio broadcasting studio were used as a background noise. 30 listeners assigned intelligibility score of each sentence with visual analog scale. Each set of sentences was provided with 20dB, 10dB, 0dB noise (same intensity with stimuli), and, finally, with no noise. As results, as background noise level increased, intelligibility scores were lowered with statistical significance. Even though in the same severity, more loud background noise showed much lower scores than less loud noise. When 10dB noise was provided, intelligibility scores showed the biggest difference among the degree of severity.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.181-189
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• 2011

The present study aimed to determine the phonological errors of children in Korean-Vietnamese speaking multicultural families through comparison analyses with those of Korean monolingual peers with phonological disorders. The subjects were 38 children aged about 4-6 years. To examine phonological errors, the Urimal Test of Articulation and Phonation (words) was used. Performances were analyzed by frequency. The results showed some differences between the two groups. There was a tendency for children in Korean-Vietnamese speaking multicultural families to show a higher frequency of phonological errors than Korean monolingual children with phonological disorders. However, the former showed lower error percentages in a few error patterns than the latter such as syllable final consonant deletion, showing similar patterns to those of the normal children. They also showed very unique error patterns such as the highest error percentage in palatal affricates. It remains to be seen if these error patterns are just delay in acquisition or phonological disorders.