• Korean Journal of Biological Psychiatry
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• v.8 no.2
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• pp.251-257
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• 2001

Backgrounds : Gamma band oscillatory activity is considered to be related to cognitive functions and illustrates that the concept of event-related oscillations bridges the gap between single neurons and neural assemblies. An event-related gamma oscillation is the time-locked responses of specific frequency, and can be identified by computing the amplitude frequency characteristics of the averaged event-related potentials(ERPs) after stimulation. Objectives : We purposed to present experimental paradigm to investigate ${\gamma}$-band oscillation activities from the recording of ERPs by using auditory oddball paradigm and investigate the difference of ${\gamma}$-band activity between schizophrenia and normal controls. Methods : The ERPs resulting from auditory stimuli with oddball paradigm in a group of schizophrenics(n=11), and also a group of age-, sex-, and handedness matched normal controls, were recorded by 128 channel EEG. The ${\gamma}$-band oscillatory activities were calculated by using time-frequency wavelet decomposition of the signal between 20 and 80Hz. The ${\gamma}$-band oscillatory activities of both groups were compared by t-test. Results : The ${\gamma}$-band oscillatory of the leads Fz, Cz, and Pz of both groups were represented well in the time-frequency maps. Significant increases of the ${\gamma}$-band activity in normal controls compared with schizophrenics were observed around 160 msec, 350 msec, and 800 msec after stimulation. Conclusions : Our results suggested that the increment in ${\gamma}$-band oscillatory activity during cognitive operations and decreased ${\gamma}$-band activity in schizophrenics may be associated with the cognitive dysfunctions and the pathophysiology of the schizophrenia.

• MALSORI
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• no.21_24
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• pp.43-89
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• 1992

In this thesis, the prominent aspect of word accent in standard Korean is studied by auditory test and acoustic analysis experiment. The definition of 'accent' is, following Hoyoung Lee's discussion(1990), to be described as 'the means whereby a focused part of an utterance is made to stand out in order to concentrate the hearer's attention on it.' That is to say, the ten of 'accent' may be described in terms of phonological phenomenon and the accented syllable can be phonetically prominent as the result of those phonological process. Prosodic features may have different characteristics in different languages whether they contain linguistically important functions or not. Thus the characteristics of word accent in standard Korean will be determined as the content and trait of prosodic features. Following this viewpoint, present study looked over prosodic features which may effect the characteristics of word accent in standard Korean, through systematic experimental procedure. And the result of this experiment has been verified by statistical method, the T-test, for the purpose of identifying the relatedness among prosodic features(parameters). This thesis, therefore, aimed to investigate the intrinsic acoustic and physical qualities of the word accent in standard Korean. Nonsense words composed by 'mal' and 'ma' which can be divided into 'heavy syllable' and 'light syllable' quoted from Hyman(1975) have been classified into 28 types with respect to syllable numbers(2 syl., 3 sy1., 4 syl.) and these words have become the target of auditory test and acoustic experiment. As the result of those experimental Procedures, the word accent in standard Korean may be said that it has a tendency of fixing first two syllables regardless of syllable numbers. The syllable types of HH, HL, LL in the first two syllables may be prominent at first syllable and the type of H may be at second syllable. Various prosodic features(parameters) including duration, intensity, and Fo(purely phonetic terms) were also strengthened in those positions. The result of this experiment can be cleared up like these : 1. The most important feature is proved as 'duration', the feature of intensity resulted in more subsidiary one than the feature of duration. 2. Fo( fundamental frequency) could be observed as having some coherent contour through almost all syllable types(99 ％), that is, in 2 syllable types, it had rising contour, in 2 syllable types, rising-falling contour, and in 4 syllable types, it contained rising-falling-rising contour. The result of auditory test was different with those contour forms of all Fo surveyed. With respect to these results, the discuss for Fo is determined' to be excluded comparing other features. 3. Finally, this thesis resulted in a decision that the word accent in standard Korean may has fixed(somewhat weaker) accent, especially fixed at first two syllables in almost all words. 4. Various kinds of syllable types related with 2,3,4 syllables, therefore, can be reclassified into 4 types of HH, HL, LH, LL following the concept of accent fixing placement(i.e. first two syllables). In these 4 types, the types of HH, HL, LL were prominent at the position of the first syllable , and the type of LH was prominent at the second syllable otherwise.

• Phonetics and Speech Sciences
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• v.10 no.1
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• pp.65-74
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• 2018

The purpose of this study is to investigate age-specific features of 2;1- to 4;1-year -olds' production of monophthongs and diphthongs through both auditory perceptual analysis and acoustic analysis. Test material included {vowel+'da'} consisting of 7 monophthongs and 10 diphthongs and meaningful words beginning with vowels. The percentage of correct vowels was used for perceptual analysis and Praat(5.2.12) was used for acoustic analysis, analyzing variables related to monophthongs and diphthongs. The results of this study are as follows: First, perceptual analysis showed that children from an age group of 2;1 to 2;8 years showed significant difference in the accuracy level of both monophthongs and diphthongs as compared to those aged 2;9 to 3;4 years and those aged 3;5 to 4;1 years. Second, the results of acoustic analysis provided that formant (F1 and F2) of monophthong, in general, tended to decrease as age increased. In terms of F2 differentiation slope and regression slope, which were diphthong-related variables, the age group of 3;5 to 4;1 years showed a large general slope change.

• The Journal of the Acoustical Society of Korea
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• v.21 no.4E
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• pp.146-155
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• 2002

We present a new technique for achieving source separation when given only a single charmel recording. The main idea is based on exploiting the inherent time structure of sound sources by learning a priori sets of time-domain basis functions that encode the sources in a statistically efficient manner. We derive a learning algorithm using a maximum likelihood approach given the observed single charmel data and sets of basis functions. For each time point we infer the source parameters and their contribution factors. This inference is possible due to the prior knowledge of the basis functions and the associated coefficient densities. A flexible model for density estimation allows accurate modeling of the observation, and our experimental results exhibit a high level of separation performance for simulated mixtures as well as real environment recordings employing mixtures of two different sources. We show separation results of two music signals as well as the separation of two voice signals.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.8 no.1
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• pp.54-58
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• 1997

Spasmodic dysphonia is an uncommon and poorly understood disorder of motor control of laryngeal speech. We analysed 88 patients with spasmodic dysphonia, using chart review. These patients had historical information evaluated for age of onset(mean 39.2 years), duration of symptoms(mean 8.8 years), sex(4.2 : 1 female to male) family history(positive in 16.7%), and primary(84.8%) and secondary(15.2%) etiology : neurological evaluation for other dystonic involvement(40.7%). Eighty-three patients(94.3%) had adductor type of spasmodic dysphonia and 4 patients were abductor type and 1 patient was mixed type. All patients had normal thyroid and parathyroid functions and among 46cases, 8 patients had abnormal brain MRI finding. seventeen patients were evaluated by auditory brainstem response parameters. four out of the 17 patiemts had prolonged wave Ⅰ-Ⅴ interpeak latency.

• MALSORI
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• no.66
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• pp.61-72
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• 2008

This paper proposes a method to improve pathological and normal voice classification performance by combining multiple features such as auditory-based and higher-order features. Their performances are measured by Gaussian mixture models (GMMs) and linear discriminant analysis (LDA). The combination of multiple features proposed by the frame-based LDA method is shown to be an effective method for pathological and normal voice classification, with a 87.0% classification rate. This is a noticeable improvement of 17.72% compared to the MFCC-based GMM algorithm in terms of error reduction.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.4
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• pp.289-298
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• 2014

Pass-by noises of various trains were recorded by binaural recorder. The measured noises were evaluated using a sound pressure level and psychoacoustic metrics objectively. To analyze a binaural effect on annoyance that can be caused by train noise, auditory experiments were performed. Through the experiments, the annoyance differences between monaural and binaural train noises, the annoyance differences due to measurement angle and the annoyance differences due to kinds of train and measurement distance were determined. A correlation analysis was conducted to determine which index can affect the annoyance more strongly. As the result, a maximum rate of change of sharpness difference between left and right channels was proposed to predict the annoyance.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.11a
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• pp.63-67
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• 1997

The ISO(International Standard Organization) has standardized MPEG-2 audio. The MPEG-2 audio compression algorithm is based upon subband analysis and exploits the human auditory characteristics to achieve a low bit rate with minimum perceptual loss of audio signal quality. This thesis presents an enhanced MPEG-2 audio encoder using multiple TMS320C30 general purpose DSP's. The developed system is made up of five slave boards and one master board. Each slave board performs susband analysis psychoacoustic parameter calculation for one channel, and the master board manages bit allocation, quantization, and bit-stream formatting for all channels. Parallel processing and pipelining techniques are used in hardware structure and fast algorithms are applied in each subroutine to implement a real-time process. The implemented system supports multichannel up to 5.1 and various bitrates.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.11a
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• pp.148-152
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• 2002

This study is to develop the Alzheimers disease (AD) detection and analysis system using event-related potential (ERP) of AD patients. We recorded ERP in an auditory oddball paradigm in mild AD (n=25), severe AD (n=12), age-matched normal aged controls (n=17), and young controls (n=7). The amplitude and latency of target P300 components were compared among 4 groups. The relationship between P300 measures and neuro psychological test (K-DRS) scores were evaluated by correlations. The latency of P300 was prolonged in AD and the effects were correlated with the severity of dementia. The P300 amplitude was not affected significantly in AD. Theres no difference between normal aged group and young group. These results suggest that the P300 component is specifically affected by Alzheimer type dementia.

• The Journal of Korea Robotics Society
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• v.2 no.3
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• pp.270-274
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• 2007

In this paper, we present a Sound Source Localization (SSL) based GCC (Generalized Cross Correlation)-PHAT (Phase Transform) and new measurement method of angle with robot auditory system for a network-based intelligent service robot. The main goal of this paper is to analysis performance of TDOA and GCC-PHAT sound source localization method and new angle measurement method is compared. We use GCC-PHAT for measuring time delays between several microphones. And sound source location is calculated by using time delays and new measurement method of angle. The robot platform used in this work is wever-R2, which is a network-based intelligent service robot developed at Intelligent Robot Research Division in ETRI.