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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Phonetics and Speech Sciences
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Journal DOI :
The Korean Society of Speech Sciences
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Volume & Issues
Volume 1, Issue 4 - Dec 2009
Volume 1, Issue 3 - Sep 2009
Volume 1, Issue 2 - Jun 2009
Volume 1, Issue 1 - Mar 2009
Selecting the target year
Formant Trajectories of English Vowels Produced by American Females
Yang, Byung-Gon ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 3~9
Acoustically English vowels are defined primarily by formant values. The measurements of the values have been usually made at a few time points of the vowel segment despite the fact that the majority of English vowel formants vary dynamically throughout the segment. This study attempts to collect acoustic data of the nine English vowels published by Hillenbrand et al. (1995) online and to examine the acoustic features of the English vowels for phoneticians and English teachers. The author used Praat to obtain the data systematically at six equidistant timepoints over the vowel segment. Obvious errors were corrected based on the spectrographic display of each vowel. Results show that the first two formant trajectories are important to separate the nine vowels within the front- or back-vowel groups. The third formant trajectories appear comparable except those of the high vowels. Second, the back vowels leave longer traces on the vowel space toward the locus of the following consonant /d/. Third, each vowel has inherent duration, pitch, and intensity patterns. The results match the findings of Yang (2009). From the results, the author concludes that dynamic spectral changes are important in specifying acoustic characteristics of English vowels. Further studies on the application of the vowel trajectories to English pronunciation lessons or on perceptual experiment of synthesized vowels are desirable.
A Study of Production Difficulties of English Bilabial Stops and Labiodental Fricatives by Korean Learners of English
Koo, Hee-San ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 11~15
The aim of this study was to identify production difficulties of Korean learners of English in their articulation of English bilabial stops /p, b/ and labiodental fricatives /f, v/. Sixty non-sense syllables and twelve words were produced three times by nine graduate students. Test scores were measured from the score board made by FluSpeak, a speech training software program, which was designed for English pronunciation practice and improvement. Results show that 1) the subjects had lower scores in producing /p, b/ than /f, v/ from all positions, and 2) subjects had lower scores in medial (inter-vocalic) position than in initial (pre-vocalic) position and in final (post-vocalic) position when they produced /p/, /b/, /f/, and /v/. The results suggest that on the whole, Korean learners of English have much difficulty in producing /b/ and that they also have more articulatory problems in intervocalic than in the other positions when they produce these bilabial stops and labiodental fricatives.
Lexical Encoding of L2 Suprasegmentals: Evidence from Korean Learners' Acquisition of Japanese Vowel Length Distinctions
Han, Jeong-Im ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 17~27
Despite many studies on the production and perception of L2 phonemes, studies on how such phonemes are encoded lexically remain scarce. The aim of this study is to examine whether L2 learners have a perceptual problem with L2 suprasegmentals which are not present in their L1, or if they are able to perceive but not able to encode them in their lexicon. Specifically, Korean learners were tested to see if they could discriminate the vowel length differences in Japanese at the psychoacoustic level through a simple AX discrimination task. Then, a speeded lexical decision task with high phonetic variability was conducted to see whether they could use such contrasts lexically. The results showed that Korean learners of Japanese have no difficulties in discriminating Japanese vowel length contrast, but they are unable to encode such contrast in their phonological representation, even with long L2 exposure.
Nonlinear Interaction between Consonant and Vowel Features in Korean Syllable Perception
Bae, Moon-Jung ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 29~38
This study investigated the interaction between consonants and vowels in Korean syllable perception using a speeded classification task (Garner, 1978). Experiment 1 examined whether listeners analytically perceive the component phonemes in CV monosyllables when classification is based on the component phonemes (a consonant or a vowel) and observed a significant redundancy gain and a Garner interference effect. These results imply that the perception of the component phonemes in a CV syllable is not linear. Experiment 2 examined the further relation between consonants and vowels at a subphonemic level comparing classification times based on glottal features (aspiration and lax), on place of articulation features (labial and coronal), and on vowel features (front and back). Across all feature classifications, there were significant but asymmetric interference effects. Glottal feature.based classification showed the least amount of interference effect, while vowel feature.based classification showed moderate interference, and place of articulation feature-based classification showed the most interference. These results show that glottal features are more independent to vowels, but place features are more dependent to vowels in syllable perception. To examine the three-way interaction among glottal, place of articulation, and vowel features, Experiment 3 featured a modified Garner task. The outcome of this experiment indicated that glottal consonant features are independent to both the place of articulation and vowel features, but the place of articulation features are dependent to glottal and vowel features. These results were interpreted to show that speech perception is not abstract and discrete, but nonlinear, and that the perception of features corresponds to the hierarchical organization of articulatory features which is suggested in nonlinear phonology (Clements, 1991; Browman and Goldstein, 1989).
Perception of English High Vowels by Korean Speakers of English
Lee, Ji-Yeon ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 39~46
This study compares the perception of English high tense and lax vowels (/i, I, u,
/) by English speakers and Korean speakers of English. The four vowels were produced in /hVd/ context by a native speaker of English, and each word's vowel duration was manipulated to range from 170ms to 290ms in 30ms increments. Two English speakers and six Korean speakers of English were asked to listen to pairs of tense and lax vowel words with manipulated vowel durations and to identify the pair by choosing either heed-hid or hid-heed for front vowels and either who'd-hood or hood-who'd for back vowels. The results show that English speakers distinguished tense vowels from lax vowels with 100% accuracy regardless of the different durations, compared to 62% accuracy for Korean speakers of English. Most errors occurred for lengthened lax vowels and shortened tense vowels. The results of this study demonstrate that Korean speakers mainly rely on vowel duration as a cue to discriminate the tense and lax vowels. The theoretical and pedagogical implications of this finding are discussed.
Building a Sentential Model for Automatic Prosody Evaluation
Yoon, Kyu-Chul ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 47~59
The purpose of this paper is to propose an automatic evaluation technique for the prosodic aspect of an English sentence uttered by Korean speakers learning English. The underlying hypothesis is that the consistency of the manual prosody scoring is reflected in an imaginary space of prosody evaluation model constructed out of the three physical properties of the prosody considered in this paper, namely: the fundamental frequency (F0) contour, the intensity contour, and the segmental durations. The evaluation proceeds first by building a prosody evaluation model for the sentence. For the creation of the model, utterances from native speakers of English and Korean learners for the target sentence are manually scored by either native teachers of English or Korean phoneticians in terms of their prosody. Multiple native utterances from the manual scoring are selected as the "model" native utterances against which all the other Korean learners' utterances as well as the model utterances themselves can be semi-automatically evaluated by comparison in terms of the three prosodic aspects . Each learner utterance, when compared to the multiple model native utterances, produces multiple coordinates in a three-dimensional space of prosody evaluation, each axis of which corresponds to the three prosodic aspects. The 3D coordinates from all the comparisons form a prosody evaluation model for the particular sentence and the associated manual scores can display regions of particular scores. The model can then be used as a predictive model against which other Korean utterances of the target sentence can be evaluated. The model from a Korean phonetician appears to support the hypothesis.
The Effects of Misalignment between Syllable and Word Onsets on Word Recognition in English
Kim, Sun-Mi ; Nam, Ki-Chun ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 61~71
This study aims to investigate whether the misalignment between syllable and word onsets due to the process of resyllabification affects Korean-English late bilinguals perceiving English continuous speech. Two word-spotting experiments were conducted. In Experiment 1, misalignment conditions (resyllabified conditions) were created by adding CVC contexts at the beginning of vowel-initial words and alignment conditions (non-resyllabified conditions) were made by putting the same CVC contexts at the beginning of consonant-initial words. The results of Experiment 1 showed that detections of targets in alignment conditions were faster and more correct than in misalignment conditions. Experiment 2 was conducted in order to avoid any possibilities that the results of Experiment 1 were due to consonant-initial words being easier to recognize than vowel-initial words. For this reason, all the experimental stimuli of Experiment 2 were vowel-initial words preceded by CVC contexts or CV contexts. Experiment 2 also showed misalignment cost when recognizing words in resyllabified conditions. These results indicate that Korean listeners are influenced by misalignment between syllable and word onsets triggered by a resyllabification process when recognizing words in English connected speech.
Bridging the Gap between Research in Linguistics and English Teaching Pedagogy: Focusing on English Pronunciation Education
Kwon, Bo-Young ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 73~84
Despite the growing interest among researchers in the field of second language (L2) phonological acquisition and its apparent contribution to linguistic and acquisition theories, there have been concerns about the lack of pedagogical application of the research findings in L2 classrooms (Levis, 1999, Derwing & Munro, 2005). Based on the belief that meeting an existing pedagogic need is something that should receive primary attention in SLA, this study attempts to bridge the gap between L2 pronunciation research and pronunciation pedagogy. In so doing, this study provides a narrative literature review of papers on L2 pronunciation published from 1994 to 2008 in Korea. The articles for review were retrieved from five database search engines. In addition, six journals where relevant articles most frequently appeared were selected and electronic searches of these six journals were conducted. A total of 117 articles which met the selection criteria were collected, and were reviewed to answer the following three research questions: a) What are the current research trends in L2 pronunciation in Korea? b) Do the research trends reflect a shift of focus on L2 pronunciation teaching? and c) What is the range of research practices in L2 pronunciation? The review of the papers indicates that the number of studies on L2 pronunciation increased sharply from 1999 to 2003. Some changes in research topics were also noticed. Research on segmental features of English was dominant from 1994 to 1998, but became more balanced with research on suprasegmentals from 2004 to 2008. This review also discusses the range of research practices in L2 pronunciation and makes suggestions for future directions in L2 pronunciation research.
Intonation Patterns of Korean Spontaneous Speech
Kim, Sun-Hee ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 85~94
This paper investigates the intonation patterns of Korean spontaneous speech through an analysis of four dialogues in the domain of travel planning. The speech corpus, which is a subset of spontaneous speech database recorded and distributed by ETRI, is labeled in APs and IPs based on K-ToBI system using Momel, an intonation stylization algorithm. It was found that unlike in English, a significant number of APs and IPs include hesitation lengthening, which is known to be a disfluency phenomenon due to speech planning. This paper also claims that the hesitation lengthening is different from the IP-final lengthening and that it should be categorized as a new category, as it greatly affects the intonation patterns of the language. Except for the fact that 19.09% of APs show hesitation lengthening, the spontaneous speech shows the same AP patterns as in read speech with higher frequency of falling patterns such as LHL in comparison with read speech which show more LH and LHLH patterns. The IP boundary tones of spontaneous speech, showing the same five patterns such as L%, HL%, LHL%, H%, LH% as in read speech, show higher frequency of rising patterns (H% and LH%) and contour tones (HL%, LH%, LHL%) while read speech on the contrary shows higher frequency of falling patterns and simple tones at the end of IPs.
Enhanced Spectral Envelope Coding Scheme Using Inter-frame Correlation for G.729.1
Cho, Keun-Seok ; Sung, Jong-Mo ; Hahn, Min-Soo ; Kim, Young-Il ; Jeong, Sang-Bae ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 97~103
This paper describes a new algorithm for encoding spectral envelope in the time domain alias cancellation (TDAC) part of G.729.1. The spectral envelope and modified discrete cosine transform (MDCT) coefficients of the weighted code-excited linear predictive (CELP) coding error in lower-band and the higher-band input signal are encoded in the TDAC part. In order to reduce allocation bits for spectral envelope coding, a new algorithm using sub-band correlation between adjacent frames is proposed. In addition, to improve the quality of decoded signals, two bit allocation strategies using reduced bits from the proposed algorithm are proposed. The performance of the proposed algorithm is evaluated in terms of objective quality and bit reduction rates. Experimental results show that the proposed algorithm increases the quality of sounds significantly.
A Study on the Sound Effect for Improving Customer's Speech Recognition in the TTS-based Shop Music Broadcasting Service
Kang, Sun-Mee ; Kim, Hyun-Deuc ; Chang, Moon-Soo ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 105~109
This thesis describes the method for well voice announcement using the TTS(Text-To-Speech) technology in the shop music broadcasting service. Offering a high quality TTS sound service for each shop requires a great expense. According to a report on the architectural acoustics the room acoustic indexes such as reverberation time and early decay time are closely connected with a subjective awareness about acoustics. By using the result the customers will be able to recognize better the voice announcement by applying sound effect to speech files made by TTS. The result of an aural comprehension examination has shown better about almost all of the parameters by applying reverb effect to TTS sound.
Spectral Pattern Based Robust Speech Endpoint Detection in Noisy Environments
Park, Jin-Soo ; Lee, Yoon-Jae ; Lee, In-Ho ; Ko, Han-Seok ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 111~117
In this paper, a new speech endpoint detector in noisy environment is proposed. According to the previous research, the energy feature in the speech region is easily distinguished from that in the speech absent region. In conventional method, the endpoint can be found by applying the edge detection filter that finds the abrupt changing point in feature domain. However, since the frame energy feature is unstable in noisy environment, the accurate edge detection is not possible. Therefore, in this paper, the novel feature extraction method based on spectrum envelop pattern is proposed. Then, the edge detection filter is applied to the proposed feature for detection of the endpoint. The experiments are performed in the car noise environment and a substantial improvement was obtained over the conventional method.
Fast Speaker Adaptation Based on Eigenspace-based MLLR Using Artificially Distorted Speech in Car Noise Environment
Song, Hwa-Jeon ; Jeon, Hyung-Bae ; Kim, Hyung-Soon ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 119~125
This paper proposes fast speaker adaptation method using artificially distorted speech in telematics terminal under the car noise environment based on eigenspace-based maximum likelihood linear regression (ES-MLLR). The artificially distorted speech is built from adding the various car noise signals collected from a driving car to the speech signal collected from an idling car. Then, in every environment, the transformation matrix is estimated by ES-MLLR using the artificially distorted speech corresponding to the specific noise environment. In test mode, an online model is built by weighted sum of the environment transformation matrices depending on the driving condition. In 3k-word recognition task in the telematics terminal, we achieve a performance superior to ES-MLLR even using the adaptation data collected from the driving condition.
Effective Combination of Temporal Information and Linear Transformation of Feature Vector in Speaker Verification
Seo, Chang-Woo ; Zhao, Mei-Hua ; Lim, Young-Hwan ; Jeon, Sung-Chae ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 127~132
The feature vectors which are used in conventional speaker recognition (SR) systems may have many correlations between their neighbors. To improve the performance of the SR, many researchers adopted linear transformation method like principal component analysis (PCA). In general, the linear transformation of the feature vectors is based on concatenated form of the static features and their dynamic features. However, the linear transformation which based on both the static features and their dynamic features is more complex than that based on the static features alone due to the high order of the features. To overcome these problems, we propose an efficient method that applies linear transformation and temporal information of the features to reduce complexity and improve the performance in speaker verification (SV). The proposed method first performs a linear transformation by PCA coefficients. The delta parameters for temporal information are then obtained from the transformed features. The proposed method only requires 1/4 in the size of the covariance matrix compared with adding the static and their dynamic features for PCA coefficients. Also, the delta parameters are extracted from the linearly transformed features after the reduction of dimension in the static features. Compared with the PCA and conventional methods in terms of equal error rate (EER) in SV, the proposed method shows better performance while requiring less storage space and complexity.
Phonics-based Rules for Improving Performance of English-to-Korean Transliteration
Kim, Min-Jeong ; Hong, Gum-Won ; Park, So-Young ; Rim, Hae-Chang ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 133~144
This paper presents a method for constructing and using transliteration rules which are based on Phonics, an instructional method for speaking and writing English letters. Conventional approaches to automatic transliteration often focused on statistical methods. However, the construction or the collection of correct transliteration examples is always the bottleneck of the statistical transliteration model. Also, in practical domains where the collection of such data is very difficult, such as education and tourism, it is reasonable to build a system without much qualified data. Furthermore, compared with Korean orthography of borrowed foreign words, the proposed approach is much easier to construct, and can generate more refined rules. The experimentation result shows that the proposed approach can improve the performance of a statistical-based transliteration system.
Acoustic Characteristics of the Voices of Korean Normal Adults by Gender on MDVP
Kim, Jae-Ock ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 147~157
The purpose of the study is to develop the normal voice database and to analyze the acoustic characteristics of Korean adults' voices by gender using MDVP. Eight categories in the 34 parameters of MDVP were analyzed in the voices of 170 Korean normal adults taken from /a/ vowel. Among them, Fundamental Frequency Parameters and Frequency Perturbation Parameters were significantly different by gender. In addition, Fundamental Frequency Parameters of our data were remarkably different from the data suggested in the MDVP program which currently used in clinics. Therefore, the data obtained from the current study can be effectively used for the diagnosis of voice disorders of Korean adults as the standard parameter values of MDVP.
A Correlation Study among Pitch, Nasalance, and Voice Quality
Park, Sung-Jong ; Yoo, Jae-Yeon ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 159~163
The purpose of this study is to conduct a correlational analysis among pitch, nasalance, and acoustic quality parameters estimated by two speech analysis softwares NasalView(version 1.31), Dr. Speech 4.5(Tiger Electronics). Thirty females and 25 males with normal voice participated in the study. The Pearson correlation coefficient was determined through a statistical analysis. The results came out as follows; Firstly, there was a correlation between
and voice quality parameters, however there was no correlation between
and nasalance. Secondly, nasalance showed a correlation with voice quality parameters.
Multiple Average Ratings of Auditory Perceptual Analysis for Dysphonia
Choi, Seong-Hee ; Choi, Hong-Shik ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 165~170
This study was to investigate for comparison between single rating and average ratings from multiple presentations of the same stimulus for measuring the voice quality of dysphonia using 7-point equal-appearing interval (EAI) rating scale. Overall severity of voice quality for 46 /a/ vowel stimuli (23 stimuli from dysphonia, 23 stimuli from control) was rated by 3 experienced speech-language pathologists (averaged 19 years; range = 7 to 40 years). For average ratings, each stimulus was rated five times in random order and averaged from two to five times. Although higher inter-rater reliability was found in average ratings than in single rating, there were no significant differences in rating scores between single and multiple average ratings judged by experienced listeners, suggesting that auditory perceptual ratings judged by well-trained listeners have relatively good agreement with the same stimulus across the judgment. Larger variations in perceptual ratings were observed for moderate voices than for mild or severe voices, even in the average ratings.
The Effects of Speaking Mode on Intelligibility of Dysarthric Speech
Kim, Soo-Jin ; Ko, Hyun-Ju ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 171~176
Intelligibility measurement is one criterion for the assessment of the severity of speech disorders especially of dysarthric persons. Rate control, usually rate reduction, is used with many dysarthric speakers to improve their intelligibility. The purpose of this study is to compare how change intelligibility of speech produced by cerebral palsic speakers according to three speaking conditions. Speech samples were collected from 10 adults with cerebral palsy were asked to speak under three speaking conditions-(1) naturally(control), (2) more slowly(rate control), (3) louder and accurately(clear speech). In a perception test, after listening to the speech samples, a group of three judges were to write down whatever they heard. The result showed that total cerebral palsic subjects were divided into two subgroups according to their intelligibility according to three speaking conditions. Some subjects showed that speech intelligibility increased greatly if asked to speak 'louder and more accurately'. and the others showed no difference of intelligibility according to the speaking conditions. This study suggested that it would be useful clinically to find out the best instruction to improve intelligibility suitable for each speaker with cerebral palsy.
The Phonatory Characteristics of the Profound Hearing-Impaired Adults' Voice: with Reference to F0, Intensity, and their Perturbations
Choi, Eun-Ah ; Park, Han-Sang ; Seong, Cheol-Jae ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 177~185
This study investigates the differences in mean F0, intensity, jitter and shimmer across hearing aid, gender and vowels. For this study, 20 hearing-impaired adults and 20 normal hearing adults as a control group were asked to read 7 Korean vowels(/
, o, u, ɯ, i,
/). 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(HL) than in the normal hearing group(NH), in the female group than in male group, and in high vowels than in low vowels. Second, intensity was significantly higher in the normal hearing group(NH) than in the hearing impaired group(HL), in male group than in female group, and in low vowels than in high vowels. Third, jitter was significantly higher in the normal hearing group(NH) than in the hearing impaired group(HL), and in female group than in male group and in the back vowels than in front vowels. Finally, shimmer was significantly higher in the normal hearing group(NH) than in the hearing impaired group(HL), and in male group than in female group. In particular, the male group showed that front vowels tend to have higher shimmer than back vowels.
Correlation Between the External Laryngeal Length and the Habitual Speaking Fundamental Frequency
Nam, Do-Hyun ; Rheem, Sung-Sue ; Choi, Hong-Sik ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 187~193
For this study, the external laryngeal lengths of 9 females and 9 males with normal voices were measured together with their ages, heights, and weights, and after they read aloud sentences for 3 minutes, their habitual speaking fundamental frequencies, speaking low pitches, speaking high pitches, and vocal fold closed quotients were measured. The Spearman rank correlation analysis on these data showed a significant negative correlation between the external laryngeal length and the habitual speaking fundamental frequency for both females and males, a significant negative correlation between the external laryngeal length and the speaking high pitch for only males, a significant negative correlation between the external laryngeal length and the speaking low pitch for both females and males, and a significant positive correlation between the external laryngeal length and the vocal fold closed quotient for only males.
A Comparative Study of Vocal Fold Vibratory Behaviors Shown in the Phonation of the /i/ Vowel between Persons who Stutter and Persons with Muscle Tension Dysphonia Using High-Speed Digital Imaging
Jung, Hun ; Ahn, Jong-Bok ; Park, Jin-Hyaung ; Choi, Byung-Heun ; Kwon, Do-Ha ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 195~201
The purpose of this study was to use high-speed digital imaging (HSDI) to compare vocal vibratory behaviors of persons who stutter (PWS) and persons with muscle tension dysphonia (PMTD) for uttering the /i/ vowel in a bid to identify the characteristics of vocal fold vibratory behaviors of PWS. This study surveyed seven developmental PWSs and seven PMTDs. The findings of the study indicated the following: first, regarding the two groups' vocal fold vibratory behaviors, of seven PWSs, three were found to be close vocal tract (VC) and four were found to be combination vocal tract (VCB). Of the seven PMTDs, one was found to be VC, and the other six were found to be VCB. These results indicate that a voiceprint which is different from the open vocal tract (VO) found in normal groups in research conducted by Jung, et al. (2008b) appeared in both groups of this study. Even between the two groups, there is a difference in the voiceprint before vocalization. Second, a VKG analysis was conducted to identify the two groups' vocal cord contact quotient. As a result, the PWS group's vocal cord contact quotient changed gradually from an irregular one at the initial vocalization stage to a regular one. The PMTD group continued the tension at the initial vocalization. Putting together all of these results, there is a difference in vocal fold vibratory behaviors between PWSs and PMTDs when they speak. Thus, there was a difference in muscular tension between the two groups.
Antidromic Electrically Compound Action Potential in Cochlear Implantees
Heo, Seung-Deok ; Jung, Sung-Wook ; Jung, Seung-Hyun ;
Phonetics and Speech Sciences, volume 1, issue 4, 2009, Pages 203~207
Electrically evoked compound action potentials (ECAP) have originated from the distal end of the auditory nerve. ECAP are characterized as the difference between the clearly large trough (N) and the following positive peak (P). N-wave occurs around
after stimulus onset and P-wave at around
. Contrary to expectations, positive peaked ECAP (pp-ECAP) was dominated by a relatively large-amplitude positive following negative peak. pp-ECAP can be recorded from the sites on or near the surgically exposed nerve trunk in animal models and/or in cases of monophasic stimulation. This study will provide the causes of the appearance of pp-ECAP in cases of cochlear implant recipients using imaging studies and medical records and statistically analysis between N-P and P-N on the amplitude input-output function (amp-I/O) for the prediction of the possibilities of clinical tools. Thirteen children participated in the study and received a Cochlear CI-24RE (CA). ECAP was recorded using auto-NRT (Cochlear Ltd., Australia) at four to five weeks post surgery. pp-ECAP was measured from 36 electrodes and typical ECAP from 220 electrodes. There was no abnormality in the imaging study and operation finding in patients with typical ECAP. pp-ECAP was found at the inner ear anormaly and ossification in imaging study and gel-state inner ear fluid was observed in the operation finding. The amplitude of pp-ECAP increased depending on current intensities, but amp-I/O increase more gradually than in the case of typical ECAP (p=0.003). pp-ECAP is antidromic potential which can record from the inner ear anormaly and ossified cochlear. Amp-I/O also depends on current intensity as well typical ECAP. These results provide a useful tool for audiological evaluation for the spiral ganglion cell status to the value of pp-ECAP.