• Korean Journal of Audiology
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• v.24 no.1
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• pp.48-52
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• 2020

Lateralization for central auditory processing (CAP) with dichotic digits recognition (DDR) test is believed expression of hemispheric dominance. Multiple sclerosis (MS) is considered an inflammatory and autoimmune alteration of central nervous system (CNS). Hearing alterations in MS and their role in CAP has not been well studied. A patient with MS and new kind of alteration in lateralization of CAP with DDR test is presented. A 53 year of age female with MS of 16 years of evolution, nine of them remained asymptomatic. She has a persistent advantage of the right ear for DDR test; but other monaural tests showed predominance of the left afferent pathway. Brainstem auditory evoked potentials (BAEPs) and long latency auditory evoked potentials (LLAEPs) showed adequate right response with deficits in organization of left response in BAEP, and N2 wave. In the contrary direction of previous publication, we disclosed advantage for DDR test, BAEP, and LLAEP in the right ear. We observed no left ear suppression; with predominance of correct left percentages in monaural psychoacoustics tests. We must keep on searching to find pathophysiological meaning of predominant of right or left auditory laterality as a CAP disorder in patients with MS.

• Journal of Audiology & Otology
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• v.24 no.1
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• pp.48-52
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• 2020

Lateralization for central auditory processing (CAP) with dichotic digits recognition (DDR) test is believed expression of hemispheric dominance. Multiple sclerosis (MS) is considered an inflammatory and autoimmune alteration of central nervous system (CNS). Hearing alterations in MS and their role in CAP has not been well studied. A patient with MS and new kind of alteration in lateralization of CAP with DDR test is presented. A 53 year of age female with MS of 16 years of evolution, nine of them remained asymptomatic. She has a persistent advantage of the right ear for DDR test; but other monaural tests showed predominance of the left afferent pathway. Brainstem auditory evoked potentials (BAEPs) and long latency auditory evoked potentials (LLAEPs) showed adequate right response with deficits in organization of left response in BAEP, and N2 wave. In the contrary direction of previous publication, we disclosed advantage for DDR test, BAEP, and LLAEP in the right ear. We observed no left ear suppression; with predominance of correct left percentages in monaural psychoacoustics tests. We must keep on searching to find pathophysiological meaning of predominant of right or left auditory laterality as a CAP disorder in patients with MS.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.12
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• pp.1223-1232
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• 2004

This study is directed toward determining the number and characteristics of psychologically meaningful perceptual dimensions required for assessing the sound quality with respect to vehicle noises, and toward identifying the acoustical and/or psychoacoustical bases underlying the preference and similarity judgments. For the purpose of analyzing the paired comparison data produced by subjective ratings we used nonmetric multidimensional scaling(MDS). The perceptual dimensions based upon preference ratings could explain 76.3 % of the variance by maximum dB(A) and sharpness acum. The correlation between objective and subjective positions of the stimuli is $R^2$=0.97(F(1,13)=195.45, p < .01), corrected $R^2$=0.93. The less the intensity of the stimulus the more becomes the subjective Position would be over-estimated relative to the objective one. The same is valid for the opposite case. The perceptual dimensions based upon similarity judgments could be accounted for 47.8 % and 23.5% of the variance, each of which might be a match for the maximum dB(A) and the sharpness acum, respectively. The correlation between objective and subjective positions of the stimuli is $R^2$=0.94(F(1,13)=92.38, p < .01), corrected $R^2$=0.87. The more the intensity of the stimulus the more becomes the subjective position would be over-estimated relative to the objective one. The same is valid for the opposite case. In other words, it is likely that the larger the amount of two stimuli which to compare would be judged similar. So far it should be further clarified that whether the relationship between preference ratings and psychological distances nay be optimized through which psycho-physical models.

• Journal of Broadcast Engineering
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• v.16 no.5
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• pp.846-860
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• 2011

The binaural auditory system of human has ability to differentiate the direction and the distance of the sound sources by using the information which are inter-aural intensity difference(IID), inter-aural time difference(ITD) and/or the spectral shape difference(SSD). These information is generated from the acoustical transfer of a sound source to pinna, the outer ears. We can create a virtual sound system using the information which is called Head related transfer function(HRTF). However the performance of 3D sound is not always satisfactory because of non-individual characteristics of the HRTF. In this paper, we propose the algorithm that uses human's auditory characteristics for accurate perception. To achieve this, excitation energy of HRTF, global masking threshold and loudness are applied to the proposed algorithm. Informal listening test shows that the proposed method improves the sound localization characteristics much better than conventional methods.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.9 s.114
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• pp.897-903
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• 2006

The reduction of the vehicle interior noise has been the main interest of noise and vibration harshness (NVH) engineers. The driver's perception on the vehicle noise is affected largely by psychoacoustic characteristic of the noise as well as the SPL. In particular, the heating, ventilation and air conditioning (HVAC) system sound among the vehicle interior noise has been reflected sensitively in psychoacoustics view point. Even though the HVAC noise is not louder than overall noise level, it clearly affects subjective perception to drivers in the way of making to be nervous or annoyed. Therefore, these days a vehicle engineer takes aim at developing sound quality as well as reduction of noise. In this paper, we acquired noises in the HVAC from many vehicles. Through the objective and subjective sound quality (SQ) evaluation with acquiring noises recorded by the vehicle HVAC system, the simple and multiple regression models were obtained for the subjective evaluation 'Pleasant' using the semantic differential method (SDM). The regression procedure also allows you to produce diagnostic statistics to evaluate the regression estimates including appropriation and accuracy. Furthermore, the neural network (NN) model were obtained using three inputs(loudness, sharpness and roughness) of the SQ metrics and one output(subjective 'Pleasant'). Because human's perception is very complex and hard to estimate their pattern, we used NN model. The estimated models were compared with correlations between output indexes of SQ and hearing test results for verification data 'Pleasant'. As a result of application of the SQ indexes, the NN model was shown with the largest correlation of SQ indexes and we found possibilities to predict the SQ metrics.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.5
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• pp.536-545
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• 2016

Household refrigerator radiates noise of which the pattern is dependent on the operating condition of its parts, such as compressor, flow fans, etc. Thus the refrigerator noise has a variety of frequency characteristics. Therefore, it is required to consider the noise characteristics for evaluating the noise quality and eventually developing the sound quality index of the refrigerator noise. In this study, five units of household refrigerator were selected to measure their noises that were used to generate sound sources for jury test of the study. The measured noises of five refrigerators were divided into ten kinds of sound source by considering operating condition and frequency characteristics. Additionally, the ten sources were each edited to have the same SPL of 30 dBA. Totally twenty kinds of sound sources (10-original SPL, 10-edited SPL 30 dBA) were evaluated by twenty-two subjects, and compared with their sound quality metrics. It was found that only the loudness of the metrics was meaningfully correlated with the subjective evaluation. The rests, sharpness, roughness and fluctuation strength, were not related. The conclusion of this study is that a new sophisticated index is necessary to be developed to qualitatively evaluate the household refrigerator noise.

• The Journal of the Acoustical Society of Korea
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• v.30 no.5
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• pp.255-264
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• 2011

The Head Related Transfer Function (HRTF) means a process related to acoustic transmission from 3d space to the listener's ear. In other words, it contains the information that human can perceive locations of sound sources. So, we make virtual 3d sound using HRTF, despite it doesn't actually exist. But, it can deteriorate some three-dimensional effect by the confusion between front and back directions due to the non-individual HRTF depending on each listener. In this paper, we proposed the new algorithm to reduce the confusion of sound image localization using human's acoustic characteristics. The frequency spectrum and global masking threshold of 3d sounds using HRTF are used to calculate the psychoacoustical differences among each directions. And perceptible cues in each critical band are boosted to create effective 3d sound. As a result, we can make the improved 3d sound, and the performances are much better than conventional methods.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.11
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• pp.1018-1024
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• 2010

The printer noise consists of the noise of the various components and parts such as motor, fan and solenoid. And the human's printing sound recognition shows various aspects when the printer starts to print papers because the components operate at the same time. Especially, printers are usually installed in the quiet office room. Therefore the printing noise is related to its competitiveness in the market. The importance of the printer sound qualities is increasing and it is necessary to develop the sound quality evaluation system, so it is a key point to identify the noise source of the printer and develop the sound quality index to each component. By using this evaluation system, it is possible to evaluate the sound quality of a prototype printer compared to the already existing one. In this paper, the printer sound quality evaluation system was developed by the following steps. Firstly, the signal processing method was applied to the recorded printing sound to identity and split the noise of components. Secondly, the MLR(multiple linear regression) method and the psychoacoustics were used to develop the sound quality index. Finally, the improvement of the printer sound quality is possible by using the result of the MLR and the path analysis. The output of this research will be applied to the development of a new printer.

• The Journal of the Acoustical Society of Korea
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• v.22 no.5
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• pp.367-374
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• 2003

In this paper, we propose an audio watermarking method using the attribute of tonal masker. First, the attribute of tonal masker as an audio watermarking attribute is analyzed. According to existing researches, it is possible to be imperceptible modulation for the energies of the frequencies that compose a tonal masker. And when the relation between the tone energy and the left or right frequency energy after various signal processing is compared with the one before the processing, very few changes are showed. We propose an audio watermarking method using these attributes of tonal masker. A watermark bit is embedded by the modulation of the difference between the two neighboring frequency energies of a tone. In the detection, the modulated the tonal masker is searched using the key wed in the embedding without original audio and the embedded watermark bit is detected. After each attack of noise insertion, band-pass filtering, re-sampling, compression, echo transform and equalization, the detection error ratios of the proposed method were average 0.11%, 1.26% for Classics and Pops. And the SDG(Subjective Diff-Grades) scale evaluation of the sound quality of the watermarked audio result in the average SDG -0.31.

• The Journal of the Acoustical Society of Korea
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• v.29 no.4
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• pp.270-277
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• 2010

In this paper, we proposed an algorithm that improves tone quality of noisy audio signals by using ICA(Independent Component Analysis) algorithm and perceptual filters. Many algorithms have been proposed to eliminate the noise from the audio signals, such as spectral subtraction method, perceptual filter, etc. The perceptual filter uses a noise that is acquired from silent ranges in the input signal. In this case, the improvement rate of tone quality decreases if the noise energy is changed by the environmental variation in a signal frame. But the proposed method estimates a noise that is changed at each frame using ICA algorithm. The estimated noise is applied to perceptual filter. To show the performance of the proposed algorithm, several tests are performed to various input signals. With the proposed algorithm, we could confirm the enhancement of tone quality in terms of segmental SNR (SSNR), noise-to-mask ratio (NMR) and Degradation Category Rating (DCR) test.