• Journal of KSNVE
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• v.9 no.5
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• pp.991-997
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• 1999

It is getting higher the demand on a good sound in a car. Like some other sensory qualities, achieving a good sound is still treated as a black-box followed by the individual taste of tuning engineers. This study aims to define the attributes of a good car audio sound and the assessment factors affecting the sound quality. With a variety of surveys on professional listening groups and car audio installers, 26 most frequently used vocabularies are selected as typical presentations of car audio sound quality. After repetitions of listening tests with deliberately selected test CD, pre-recorded 15 different digital car-recordings, headphones replay system, and three different listening groups, it is proved that there are at least 5 different assessment factors which significantly affect the car audio sound quality. They are high fidelity, spectral balance, tonal accuracy, sound stage and acoustic fault.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.489-494
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• 2000

제품과 사용자간에 필연적으로 존재하는 소리를 쾌적하게 하기 위한 연구로서 자연음 6종과 소음 6종의 음압(dB)이 비슷하도록 조절하였을 때 소리의 어떠한 물리적 특성이 긍/부정감성에 주된 영향을 미치는지를 파악하기 위하여 남/녀 각각 35명씩의 대학생들에게 7점척도의 8가지 형용사 쌍을 이용한 음질평가 청감실험을 한 결과 물소리를 포함한 자연음은 소음보다 대체로 긍정감성이 높게 평가되었고 긍정감성과 심리음향인자와의 상관성은 Loudness의 -0.37을 비롯하여 "-"상관성을, Unbiased annoyance와 심리음향인자들과의 상관성은 Loudness의 0.92를 비롯한 "+" 상관성을 각각 갖었으며 여자는 남자보다 긍/부정감성에 더욱 예민하게 반응하는 것으로 나타났다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1157-1160
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• 2002

This paper describes an investigative study for Wind Noise of Passenger Cars. Using statistical method of analyzing jury preference data, we extract important sound quality metrics for subjective feeling and also md important frequency band. It will be helpful for development of wind Noise improvement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.481-482
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• 2014

• The Journal of the Acoustical Society of Korea
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• v.39 no.2
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• pp.113-119
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• 2020

Motor noise is a major concern in order to improve perceptual feeling of car interior sound due to increased motor usage in passenger cars. The purpose of this study is to propose factors that can represent the acoustic performance of motor noise according to the change of load. To this end, at first, it is shown that power spectrum and total loudness are not fit for noise performance, and then, PN_B, partial loudness related to the brush friction component, and PN_R, partial loudness related to the torque ripple component are investigated as factors representing motor noise. The performance curve of motor noise using PN_B and PN_R is proposed to identify trends of motor noise according to the loads. The curve could be a guide for the noise control, the selection of motor, and the improvement of a system.

• The Journal of the Acoustical Society of Korea
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• v.19 no.5
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• pp.65-70
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• 2000

It is blown that the loudness is one of the most important metrics in assessing the sound quality and a calculation method for loudness has been standardized for steady sounds. In this study, a new loudness model is suggested for dealing with the transient sound for a unified analysis of various practical sounds. A signal processing technique is introduced for this purpose, which is required for the band subdivision and the prediction of band-level change of transient sounds. In addition, models for the post-masking and the temporal integration are adopted in the analysis of the loudness of transient sounds. In order to solve the problem of the conventional loudness model in the pure-tone signal processing, a critical band filter is employed in the analysis, which consists of 47 critical filters having a filter spacing of a half of the critical bandwidth. For testing the effectiveness of the present model, the predicted responses are compared with the experimental data and it is observed that they are in good agreements.

• Journal of ILASS-Korea
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• v.19 no.4
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• pp.204-210
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• 2014

Experimental study was conducted to investigate the effect of EGR(exhaust gas recirculation) on engine noise using single cylinder combustion ignition engine. Under constant engine rotary speed of 1200 RPM, 8 mg fuel quantity was injected with 15, 18 and 21% of oxygen ratio and 1400 bar of injection pressure. Using the in-cylinder pressure data acquired by a piezoelectric transducer, the engine performance parameters were calculated. Radiated engine noise measured for 10 seconds was analyzed using spectral characteristics and sound quality metrics such as loudness, sharpness, roughness. From the obtained engine performance parameters and sound quality metrics, effect of oxygen ratio of the premixed air, start of injection timing on frequency characteristic and sound quality metrics were analyzed. Correlation analysis was conducted between MPRR(maximum pressure rise rate), RI(ringing intensity) and sound quality metrics. RI was identified as the most important factor having influence on the sound quality metrics.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.5 s.110
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• pp.485-494
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• 2006

The state-of-the-art of low-noise fan design usually includes the consideration of optimal sound level and sound quality. The influential design parameters of the noise level by the centrifugal fan were selected based on the preliminary test. The centrifugal fans were designed according to the experiment plan method by specifying the selected design parameters. The experiment with these machined mock-up's of centrifugal impellers suggested the major design parameters among many, having impacts upon the indices of sound quality (e.g. loudness, sharpness, roughness and fluctuation strength) at the same operation point. With the response surface method, the major design parameters selected thereafter were analyzed to estimate each contribution upon the sound quality of the centrifugal fan, and the optimal values were drawn by the consideration of the sound quality levels and their regression equations. In addition, the validity of the regression equations was numerically verified by means of the coefficient of determination. Furthermore, the mechanism by which the centrifugal fan impeller influences the determinants of its sound quality was suggested.

• The Journal of the Acoustical Society of Korea
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• v.20 no.7
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• pp.3-12
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• 2001

It is known that the roughness is one of the most important metrics in assessing the sound quality. In this study, a new roughness model is suggested by combing the previous auditory filter model and several signal processing methods for the enhancement of calculation efficiency and accuracy. For testing the usefulness of the present model, the predicted responses are compared with the experimental data and it is observed that they are in good agreements. Also, it is found that the previous models have limitations to search frequency components mainly contributed to overall roughness. By modifying the correlation criteria of the present model, the revised model for the proper estimation of roughness-contributed components is embedded.

• The Journal of the Acoustical Society of Korea
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• v.19 no.7
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• pp.66-76
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• 2000

Acoustic performance of loudspeakers for sound reproduction has been qualitatively evaluated by using the listening test by juries in the development and final evaluation stages. However, the subjective evaluation method has many problems in the viewpoint of reliability and repeatability that are mainly related to the jury performance, as well as time and economy. In this reason, objective techniques should be tried to evaluate the acoustic performance of loudspeakers as well as the conventional subjective test. The object of this study is to find if there is any correlation between the statistically treated in test results and the measured results based on the loudness of reproduced sound signals. For the four-step statistical analysis, the analysis of variance (ANOVA) and Tukeys method are employed for dealing with the data from the listening test. For the objective evaluation, Zwickers loudness considering the human hearing characteristics is calculated for the measured sound signal emitted from each loudspeaker and the objective ratings such as fidelity rating (FR) and softness rating (SR) is suggested. The correlation between two ratings has been demonstrated for an actual set of loudspeakers using FR, SR and correlation coefficient. The method in this study can be useful in statistically evaluating commercial or prototype loudspeakers without using very time-consuming and expensive subjective testing.