• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.1
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• pp.100-106
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• 2017

Sound quality engineering in automobile noise applications has become more and more important under the current quiet driving condition because various noise components masked under high noise level can be audible in quieter driving situation. Many researches have been carried out for subjective and objective assessments on automobile sounds and noises. In particular, the interior sound quality has been one of research fields that can give high-quality feature to automobile products. Although many works related to the interior sound quality have been progressed or completed in foreign countries, limited research results are presented in the country. In the study, subjective assessments are first performed with 20 subjects to select perceptual adjectives suitable to the assessment of car interior noises during acceleration. The selected perceptual adjectives are employed as the assessment scales to evaluate the acceleration noises in questionnaire procedures using 35 subjects, for which several noises are created through digital filtering of the acceleration noises measured. Mean values and standard deviations for subjective assessment scores obtained by the questionnaire procedures are calculated and their reliability are also verified. Finally, various statistical analyses such as the correlation analysis and the factor analysis are carried out to reveal the interrelationship between the assessment scales and the spectrum components of the acceleration noises.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.5936-5954
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• 2018

Eight out of the top ten the largest technology companies in the world are involved in some way with the coming mobile VR revolution since Facebook acquired Oculus. This trend has allowed the technology related with mobile VR to achieve remarkable growth in both academic and industry. Therefore, the importance of reproducing the acoustic expression for users to experience more realistic is increasing because auditory cues can enhance the perception of the complicated surrounding environment without the visual system in VR. This paper presents a audio downmixing system for auralization based on hardware, a stage of sound rendering pipelines that can reproduce realiy-like sound but requires high computation costs. The proposed system is verified through an FPGA platform with the special focus on hardware architectural designs for low power and real-time. The results show that the proposed system on an FPGA can downmix maximum 5 sources in real-time rate (52 FPS), with 382 mW low power consumptions. Furthermore, the generated 3D sound with the proposed system was verified with satisfactory results of sound quality via the user evaluation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.9
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• pp.628-636
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• 2015

In this study, theoretical and experimental analyses were performed for creating and moving the zone of quiet(ZoQ) to the ear location of a sitter by using active sound control technique. As the ZoQ is actively created at the location of the error microphone basically with an active sound control system using an algorithm such as the filtered-x least mean square(FxLMS), the virtual microphone control(VMC) method was considered to move the location of the ZoQ to around the sitter`s ear. A chair system with microphones and loudspeakers on both sides was manufactured for the experiment and thus an active headrest against the swept narrowband noise as the primary noise was implemented with a real-time controller in which the VMC algorithm was embedded. After the control experiment with and without the VMC method, the location variation of the ZoQ by analyzing the error signals measured by the error and the virtual microphones. Therefore, it is observed that the FxLMS with the VMC technique can provide the re-location of the ZoQ from the error microphone location to the virtual microphone location. Also it is found that the amount of the attenuation difference between the two locations was small.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.455-461
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• 2000

A multichannel signal processing algorithm for generating real time virtual sound field was proposed. Evaluation of the system performance was done by an objective function that minimizes the difference between the real and generated signals at each control point. Since impulse responses at the surface of a rigid sphere show characteristics similar to those of real HRTF, a rigid sphere model was adequate to simulate the multichannel sound system. A two-channel system and two four-channel systems were studied with various combinations of source locations and speaker positions. The results show that a two-channel system has its best configuration when the angle spanned by the loudspeakers is less than $60^{\circ}$. In the case of four-channel systems, the overall performance was highly improved with one pair of speakers fixed at an optimal position. Left/right symmetry was a reasonable choice, but the additional front/back symmetry degraded the performance of system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.364-369
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• 2012

The vehicle sound classified into driving sound due to power-train, operating sound due to electric motor like sunroof, door lock and electronic sound. These vehicle sound has various features depend on the characteristic of sound that user required. And it based on cultural and regional difference of user. In this study, the user required vehicle sound characteristics for luxury sedan was investigated in overall viewpoint. And virtual target sound was developed through the result of user preference investigation. Next, Jury test was carried out in Germany, USA and Korea for evaluating the target sound. And the regional and individual difference of preference was analyzed through the result of jury test. This result of research will be contributed to design of vehicle sound quality and target sound setting.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.4
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• pp.319-326
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• 2004

The soundscape is a novel attempt to offer comfortable sound environments at the urban public spaces by adding pleasant sounds and removing unagreeable ones. Most important factors to be considered therein are to determine what kind of sounds to offer and how to adjust them to the changing circumstances. But, installing, maintaining and adjusting the soundscape system directly in the field will ensue numerous problems as well as high costs. Thus, it is essential to devise a test method to analyse and verify the outcome before the actual installation in the field takes place. This study aims at devising the instrument system that enables to control. with a great ease, numerous variables. reproduce most agreeable sound sources, and can verify the effects on the virtual simulatory settings, which is named as Virtual Acoustic Field Simulation System (VAFSS).

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.186.1-186.1
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• 2005

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.439-444
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• 2001

We provide methods to simulate noise propagation for an outdoor environment. Forward tracing method traces sound vectors from sources to receivers while geometry based computation finds all possible sound propagation between sources and receivers geometrically. We discuss defects in relying on a forward tracing method, and suggest a geometry based method. Geometry based method considers all possible direct and indirect(propagation via limited number of reflections) sound propagation saving computational time compared to forward sound tracing. Our simulation results are visualized using VRML(Virtual Reality Modeling Language).

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.909-912
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• 2017

In implementing a computerized virtual training system, the auditory element is responsible for the human cognitive ability following visual elements. Especially, the improvement of hearing ability is closely related to the performance of the training, and it contributes to improvement of the training effect. In this paper, we propose a sound system that is necessary for constructing such a virtual training system as a test system that can use a sound source using a head related transfer function (HRTF). Functional and auditory tests were performed to evaluate system performance.

• Journal of Navigation and Port Research
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• v.27 no.2
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• pp.145-153
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• 2003

The presence-feeling enhancement method of a Virtual Reality (VR) simulator is proposed in this paper. The method is to increase realistic human feeling by mutual synergy effect between stereoscopic image and three-dimensional (3D) sound. In order to test the influence of mutual synergy effect, subject assessment with five university students is carried out using VR ship simulator having PC monitor and LCD shutter glasses. It I found that the averaged scale value of image naturalness is increased by 0.5 from $I_{nat}$=3.1 to 3.6 when blending stereoscopic images with 3D sound, and the averaged score value of sound localization is increased by 10% from $A_{SL}$ = 70~75% to $A_{SL}$ = 80~85% when blending 3D sound with stereoscopic image. In conclusion, the results show that the proposed method is able to increase the presence feeling in the VR simulator.