• Journal of Korea Multimedia Society
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• v.16 no.4
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• pp.510-519
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• 2013

In this paper, we propose a voice-annotation browsing system that make the reading-disabled people to be able to find and play the existing voice-annotations. The proposed system consists of 4 steps: input, ranking & recommendation, search, and output. For the reading-disabled people depending only on the auditory sense, all steps can accept voice commands. To evaluate the effectiveness of our system, we design and implement an android-based mobile e-book application supporting the voice-annotation browsing ability. The implemented system is tested by a number of blind-folded users. As a result, we can see almost all the reading-disabled people can successfully and easily reach the existing voice-annotations they want to find.

• Progress in Superconductivity
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• v.12 no.1
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• pp.57-61
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• 2010

We have developed a whole-head MEG system for basic brain research and clinical application. The sensor system consists of a 152 SQUID gradiometer array oriented and located in a suitable way to cover a whole head of the human. The system measures magnetic fields generated by neuronal currents in the brain to get information on the brain activities. For this purpose, the field sensitivity determined by the position, orientation and geometry of the pickup coil as well as amplification factor of the electronic circuits should be known precisely. However, the position and orientation of the pickup coil might be changed from the designed specifications during cool down of the dewar and it is necessary to characterize the field sensitivity. In this study, we made calibration systems to determine the actual position and orientation of the 152 pickup coils and compared the localization results of the N100m source in the auditory cortex.

• Journal of Broadcast Engineering
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• v.13 no.5
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• pp.574-585
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• 2008

3D sound is of central importance for the virtual reality system, and is becoming increasingly important for the auditory displays and for the human-computer interaction. In this paper, we propose a novel real-time 3D sound representation system for virtual reality. At first, we propose a calculation method of the impulse response for virtual space. To transmit the information of the virtual space, we propose an enhanced DXF file type that contains the material information. And then, we implement the multi-channel sound panning system. we perform the experiment based on computer simulation and prove the utility of the proposed method.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.2
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• pp.15-21
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• 2009

Hearing loss is one of the most common birth defects among infants. Most of hearing-impaired children are not diagnosed until 1 to 3 years of age - which is too late for the critical period (6 month) for normal speech and language development. If a hearing impairment is identified and treated in its early stage, child's speech and language skills could be comparable to his or her normal-hearing peers. For these reasons, hearing screening at birth and throughout childhood is extremely important. ABR (Auditory brain-stem response) is nowadays one of the most reliable diagnostic tools in the early detection of hearing impairment. In this study, we have developed the system that automatically detects if there is hearing impairment or not for infants or children. For future studies, it will be developed as a portable system to be able to take a measurement not only in sound proof room but also in nursery for neonates.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.3
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• pp.48-55
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• 2010

Hearing impairment is one of the most common birth defects among infants. Significant bilateral hearing impairment have profound effects on speech and language development. But it can be prevented, if a hearing impairment is identified and treated in its early stage. ABR (auditory brainstem response) is useful screening tool for new born hearing test. However, the interpretation of conventional ABR should be done by a experienced audiologist and testing takes some time. Therefore, A-ABR(automated ABR) which detect ABR peak automatically have been developed recently. In contrast to A-ABR researches became active in overseas, there has been little study in Korea. In this study, we have developed a portable A-ABR system based on the results of our previous study. For the evaluation of the developed system, the clinical trials were performed on adults and infants. As a results, it showed good sensitivity (94.4%) and specificity (92.2%), and accuracy (93.0%) between clinical diagnosis and the developed A-ABR test.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.12
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• pp.1150-1158
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• 2013

Artificial cochlear implant system is known as the most efficient and widespread device to patients who have cochlear disorder. However, current commercialized artificial cochleas have inconveniences because of large volume size and high power consumption, requiring further research on improvements in terms of the size, power, and performance. In this paper, we will introduce our fully implantable artificial cochlear implant system, where small-size sensors and actuators are wirelessly connected, focusing on communication system design and its performance simulation.

• ETRI Journal
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• v.22 no.2
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• pp.11-19
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• 2000

If the right and left signals of a binaural sound recording are reproduced through loudspeakers instead of a headphone, they are inevitably mixed during their transmission to the ears of the listener. This degrades the desired realism in the sound reproduction system, which is commonly called 'cross-talk.' A 'cross-talk canceler' that filters binaural signals before they are sent to the sound sources is needed to prevent cross-talk. A cross-talk canceler equalizes the resulting sound around the listener's ears as if the original binaural signal sound is reproduced next to the ears of listener. A cross-talk canceler is also a solution to the problem-how binaural sound is distributed to more than 2 channels that drive sound sources. This paper presents an effective way of building a cross-talk canceler in which geometric information, including locations of the listener and multiple loudspeakers, is divided into angular information and distance information. The presented method makes a database in an off-line way using an adaptive filtering technique and Head Related Transfer Functions. Though the database is mainly concerned about the situation where loudspeakers are located on a standard radius from the listener, it can be used for general radius cases after a distance compensation process, which requires a small amount of computation. Issues related to inverting a system to build a cross-talk canceler are discussed and numerical results explaining the preferred configuration of a sound reproduction system for stereo loudspeakers are presented.

• Progress in Superconductivity
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• v.11 no.1
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• pp.78-82
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• 2009

We have fabricated a helmet type magnetoencephalogrphy(MEG) with a $1^{st}$ order gradiometer in vacuum to improve the signal-to-noise ratio(SNR) and the boil-off rate of liquid helium(LHe). The axial type first-order gradiometer was fabricated with a double relaxation oscillation SQUID(DROS) sensor which was directly connected with a pickup coil. The neck space of LHe dewar was made to be smaller than that of a conventional dewar, but the LHe boil-off ratio appeared to increase. To reduce the temperature of low Tc SQUID sensor and pickup coil to 9 K, a metal shield made of, such as copper, brass or aluminum, have been usually used for thermal transmission. But the metal shield exhibited high thermal noise and eddy current fluctuation. We quantified the thermal noise and the eddy current fluctuation of metal. In this experiment, we used the bobbin which was made of an alumina to wind Nb superconductive wire for pickup coil and the average noise of coil-in-vacuum type MEG system was $3.5fT/Hz^{1/2}$. Finally, we measured the auditory evoked signal to prove the reliability of coil-in-vacuum type MEG system.

• Progress in Superconductivity
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• v.11 no.1
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• pp.30-35
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• 2009

We have investigated the characteristics of a superconductive Pb shield for hemispherical shape and plate to improving signal-to-noise ratio(SNR) of biomagnetism. We measured the shielding factor for the position of helmet shape Pb and for changing the distance from Pb surface. To make a uniform magnetic field, a $1.5m{\times}1.5m$ set of the helmholtz coils activated at several frequencies. The shielding factor of hemispherical shape Pb was from 20 to 57 dB and of Pb plate was about $6{\sim}26dB$ as a function of distance from the lead surface. The shielding factor was rapidly reduced as increasing the distance from Pb surface. The white noise of superconductive quantum interference device(SQUID) with a superconductive shield was about $12fT/Hz^{1/2}$ at 1 Hz, $7fT/Hz^{1/2}$ at 100 Hz. The white noise was more increased about two times than conventional SQUID system without Pb shielding. An auditory signal was measured by first order gradiometer and magnetometer with Pb superconductive shield and compared the SNR. The SQUID system with Pb shield had better performance at low frequency noise level.

• The Journal of the Acoustical Society of Korea
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• v.30 no.2
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• pp.100-106
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• 2011

Music recordings have been digitalized such that huge size of music database is available to the public. Thus, the automatic classification system of music genres is required to effectively manage the growing music database. Mel-Frequency Cepstral Coefficient (MFCC) is a popular feature vector for genre classification. In this paper, the combined super-vector with Decorrelated Filter Bank (DFB) and Octave-based Spectral Contrast (OSC) using texture windows is processed by Support Vector Machine (SVM) for genre classification. Even with the lower order of the feature vector, the proposed super-vector produces 4.2 % improved classification accuracy compared with the conventional Marsyas system.