• Journal of Institute of Control, Robotics and Systems
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• v.21 no.1
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• pp.59-64
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• 2015

In this paper, we found the usefulness of the deep belief network (DBN) in the fields of brain-computer interface (BCI), especially in relation to imagined speech. In recent years, the growth of interest in the BCI field has led to the development of a number of useful applications, such as robot control, game interfaces, exoskeleton limbs, and so on. However, while imagined speech, which could be used for communication or military purpose devices, is one of the most exciting BCI applications, there are some problems in implementing the system. In the previous paper, we already handled some of the issues of imagined speech when using the International Phonetic Alphabet (IPA), although it required complementation for multi class classification problems. In view of this point, this paper could provide a suitable solution for vowel classification for imagined speech. We used the DBN algorithm, which is known as a deep learning algorithm for multi-class vowel classification, and selected four vowel pronunciations:, /a/, /i/, /o/, /u/ from IPA. For the experiment, we obtained the required 32 channel raw electroencephalogram (EEG) data from three male subjects, and electrodes were placed on the scalp of the frontal lobe and both temporal lobes which are related to thinking and verbal function. Eigenvalues of the covariance matrix of the EEG data were used as the feature vector of each vowel. In the analysis, we provided the classification results of the back propagation artificial neural network (BP-ANN) for making a comparison with DBN. As a result, the classification results from the BP-ANN were 52.04%, and the DBN was 87.96%. This means the DBN showed 35.92% better classification results in multi class imagined speech classification. In addition, the DBN spent much less time in whole computation time. In conclusion, the DBN algorithm is efficient in BCI system implementation.

• Phonetics and Speech Sciences
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• v.4 no.2
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• pp.41-49
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• 2012

The purpose of this paper is to extract the vowel formants of the ten young male speakers from the Buckeye Corpus of Conversational Speech [1] and to analyze them in comparison to earlier works in terms of various phonetic factors that are expected to affect the realization of the formant distribution. The first two formant frequency values were automatically extracted with a Praat script along with such factors as the place of articulation, the content versus function word information, syllabic stress information, the location in a word, location in utterance, speech rate of three consecutive words, and the word frequency in the corpus. The results indicated that the formant patterns from the corpus were very different from those of earlier works although the overall pattern was similar and that the factors were strongly responsible for the realization of the two formants. The purpose of this paper is to extract the vowel formants of the ten young male speakers from the Buckeye Corpus of Conversational Speech [1] and to analyze them in comparison to earlier works in terms of various phonetic factors that are expected to affect the realization of the formant distribution. The first two formant frequency values were automatically extracted with a Praat script along with such factors as the place of articulation, the content versus function word information, the syllabic stress information, the location in a word, the location in an utterance, the speech rate of the three consecutive words, and the word frequency in the corpus. The result indicated that the formant patterns from the corpus were very different from those of earlier works although the overall pattern was similar and that the factors were strongly responsible for the realization of the two formants.

• The Journal of Advanced Prosthodontics
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• v.2 no.3
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• pp.71-76
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• 2010

PURPOSE. The purpose of this study was to compare men with women in terms of speech intelligibility, to investigate the validity of objective acoustic parameters related with speech intelligibility, and to try to set up the standard data for the future study in various field in prosthodontics. MATERIALS AND METHODS. Twenty men and women were served as subjects in the present study. After recording of sample sounds, speech intelligibility tests by three speech pathologists and acoustic analyses were performed. Comparison of the speech intelligibility test scores and acoustic parameters such as fundamental frequency, fundamental frequency range, formant frequency, formant ranges, vowel working space area, and vowel dispersion were done between men and women. In addition, the correlations between the speech intelligibility values and acoustic variables were analyzed. RESULTS. Women showed significantly higher speech intelligibility scores than men and there were significant difference between men and women in most of acoustic parameters used in the present study. However, the correlations between the speech intelligibility scores and acoustic parameters were low. CONCLUSION. Speech intelligibility test and acoustic parameters used in the present study were effective in differentiating male voice from female voice and their values might be used in the future studies related patients involved with maxillofacial prosthodontics. However, further studies are needed on the correlation between speech intelligibility tests and objective acoustic parameters.

• Phonetics and Speech Sciences
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• v.9 no.4
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• pp.107-114
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• 2017

The purpose of the current study was to compare selected acoustic and electroglottographic measures (closed quotient, pitch, and loudness) among vowel phonation, traditional voiced lip trill ($VLT_T$), modified voiced lip trill methods ($VLT_M$). A total of 21 participants without voice complaints produced 4-second long samples using each phonation method. Results indicated that mean closed quotient of $VLT_M$ was higher than that of vowel phonation and $VLT_T$, while its range and standard deviation measures were higher than those of vowel phonation. Mean, range, standard deviation, maximum of pitch measures of $VLT_M$ were higher than those of vowel phonation. Lastly, mean and maximum loudness of the $VLT_M$ were higher than $VLT_T$. In conclusion, the current data indicate the possibility to use the $VLT_M$ as a training method for singing or a strategy to facilitate generalization effect of voice therapy. Current results also reflect the necessity for further study pertaining to the long-term effect of the $VLT_M$ training method. Clinical implications are discussed.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.10 no.2
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• pp.140-148
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• 1999

The use of obturator is the prosthetic rehabilitation approach for restoration of the defected maxillary shape and function for the patients with palatal defect. The obturator can change the shape of vocal tract and nasality, but few reports on the effects of the change were presented. So, the authors performed the experimental study to compare the difference between the sizes of vowel triangles produced by maxillectomized patients before and after obturator-wearing and to consider how much improvement in speech intelligibility can be expected by obturator wearing. The 8 patients who were totally maxillectomized due to palatal cancer were participated as subjects. They produced 5 vowels(/a/, /i/, /u/, /e/, /o/) before and after obturator-wearing. The formants of the vowels were analyzed by the spectrogram of CSL, and their speech intelligibility were judged by normal 8 listeners. As results, the frequency of the first and the second formant showed no significant difference between the articulation before and after wearing, but the comparison of the sizes of vowel triangles, related with the speech intelligibility, showed significant difference. The vowel triangle of the articulation after wearing was larger than that of the articulation before wearing. /i/ showed the lowest speech intelligibility score among the vowel articulation before wearing. After wearing obturators, their scores increased on the whole, especially, in /a/, but the intelligibility of /u/ decreased after wearing.

• Speech Sciences
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• v.7 no.4
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• pp.59-72
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• 2000

Vocal tract resonances are of paramount importance to voice sounds. Resonance frequencies determine vowel quality and the personal voice timber. The aim of this study was to make an effective diction program according to tuning formant frequencies by adjusting the vocal tract shape in professional voice users. Twelve male student singers and eleven female student singers participated in this study. The subjects repeated five simple vowels /a, e, i, o, u/ in normal speech and singing. The spoken vowels and sung vowels were measured by formant frequencies and the singer's formant frequencies using CSL and DSP Sona-Graph. Separately, Plot formants program was used to draw the vowel chart. The results were as follows. (1) Total formant frequencies of female singers were 11% higher than those of males singers in singing. (2) The F1 and F3 of sung vowels increased compared to F1 and F3 spoken vowels. However, The F2 of sung vowels decreased in comparison with F2 of spoken vowels. (3) Posterior vowel /u/ were moved anteriorly. This phenomenon seemed to be due to head voice singing training. (4) Singer's formant frequencies in student singers appeared according to the part: 2560 Hz for baritone, 2760 Hz for Tenor, 2821 Hz for Mezzo soprano and 3420 Hz for soprano.

• Phonetics and Speech Sciences
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• v.15 no.1
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• pp.1-7
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• 2023

This study investigated the influences of probabilistic accessibility of the word being produced - as determined by its usage frequency and neighborhood density - on native and high-proficiency L2 speakers' realization of six English monophthong vowels. The native group hyperarticulated the vowels over an expanded acoustic space when the vowel occurred in words with low frequency and high density, supporting the claim that vowel forms are modified in accordance with the probabilistic accessibility of words. However, temporal expansion occurred in words with greater accessibility (i.e., with high frequency and low density) as an effect of low phonotactic probability in low-density words, particularly in attended speech. This suggests that temporal modification in the opposite direction may be part of the phonetic characteristics that are enhanced in communicatively driven focus realization. Conversely, none of these spectral and temporal patterns were found in the L2 group, thereby indicating that even the high-proficiency L2 speakers may not have developed experience-based sensitivity to the modulation of sub-categorical phonetic details indexed with word-level probabilistic information. The results are discussed with respect to how phonological representations are shaped in a word-specific manner for the sake of communicatively driven lexical intelligibility, and what factors may contribute to the lack of native-like sensitivity in L2 speech.

• Phonetics and Speech Sciences
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• v.12 no.3
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• pp.85-94
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• 2020

Vowel articulation in subjects related to speech disorders seems to be difficult. A chant method that properly reflects the characteristics of language could be used as an effective way of addressing the difficulties. The purpose of this study was to find out whether the chant method is effective as a means of enhancing vowel articulation. The subjects of this study were 60 normal adults (30 males and 30 females) in their 20s and 30s whose native language is Korean. Eight utterance conditions including chanting and reading conditions were recorded and their acoustic data were analyzed. The results of the analysis of the acoustic variables related to the formant confirmed that the F1 and F2 values of the vowel formants are increased and the direction of movement of the center of gravity of the vowel triangle is statistically significantly forwarded and lowered in the chant method in both the word and the phrase context. The results also proved that accent is the most influential musical factor in chant. There was no significant difference between four repeated tokens, which increased the reliability of the results. In other words, chanting is an effective way to shift the center of gravity of the vowel triangle, which suggests that it can help to improve speech intelligibility by forming a desirable place for articulation.

• Phonetics and Speech Sciences
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• v.5 no.4
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• pp.71-78
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• 2013

The purpose of this study was to compare the acoustic voice outcomes of children with cochlear implant to those of children with normal hearing. Participants were 41 children using unilateral cochlear implant (18 males and 23 females), and children with normal hearing from the same age and sex. Mean age of implantation was approximately 3 years old, mean duration of implant use was 4 years in CI group. Acoustic analyses were performed using MDVP of CSL. Speech samples were 3 sustained vowels, /a, i, u/. 9 parameters (F0, Fhi, Flo, Jitter, Shimmer, vF0, vAm, NHR, and SPI) were analyzed. Children with CI did not show the significant differences in those parameters after the vowel /a/ phonation. Meanwhile, there were significantly different results in F0, Fhi, vF0, and SPI after /i, u/ phonation. These results revealed that differences of voice characteristics in children with CI compare to children with NH persist regarding vowel context. It suggests that high vowels would recommend as speech samples for acoustic evaluation. Futhermore perceptual analysis and speech therapy for phonation control would be necessary for children with CI.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.13 no.2
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• pp.124-131
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• 2002

Speech characteristics of patients with cleft palates are resonance disorders, articulatory disorders and voice disorders. The purpose of this study is to find the acoustic, physiological and articulatory characteristics of cleft palate speakers. Thirteen control groups and 3 cleft palate patients participated in this experiment. Test words were composed of simple vowels and consonants imbedded in low vowel /a/, /p 'ap'i/ and /sasi/ according to the evaluation experiments. CSL, Video fluoroscopy, Fiberscope and Nasometer were used to analyze VOT, vowel formants, profiles of articulator, VP port images and nasalance. The results are as follows : (1) The nasalance of cleft palate patients in the high vowel /i/, stop sounds and fricative sounds were 60%, 34.8% and 44.1%, respectively. These values were higher than those of the control group. (2) Posterior articulatory movements /k'a/ in patients with cleft palates showed backward movement in comparison with the control group on Video Fluoroscopic images and palatograms. These results suggested that patients with cleft palate have the compensatory oral sounds to close the VP port. (3) The VOT in patients with cleft palates was longer than that of the control group.