• Proceedings of the Acoustical Society of Korea Conference
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• 1995.06a
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• pp.155-158
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• 1995

150~7,000Hzd의 확대역 전화를 위한 전화 전송특성 설계지침으로 활용하기 위해, 확대역과 300~3400Hz 의 협대역 전화에 대한 통화품질 평가결과를 비교/분석하였다. 토화품질 평가는, 조정법에 의한 선호 라우드니스 레벨고 ㅏ동가 라우드니스 레벨 조정실험, 그리고 단음절 명료도평가로 구성되었다. 선호 라우드니스 레벨 조정실험의 결과, 협대역과 확대역 음성에 대한 피험자의 선호레벨이 각각 70.7dB 및 68.6dB로 약 2dB의 차이를, 피험자간 분산은 2.12와 6.11로 의미있는 차이를 보였는데, 이것은 음성대역의 확장에 따라 사용자들의분산이 크기 때문에 확대역 전화에서 수화음량 조절기능이 필요함을 증명한 결과이다. 그리고, 협/확대역 조건에서의 100개 단음절에 대한 명료도 실험 결과에서, 전체 명료도 점수간에는 통계적으로 의미있는 차이를 보이지 않았지만 단음절중 3,400Hz이상에서 많은 에너지를 갖는, 파열음 'ㅌ', 파찰음 'ㅈ', 'ㅉ', 'ㅊ', 그리고 마찰음 'ㅅ', 'ㅆ' 으로 시작하는 20개 단음절에 대한 부분명료도에 있어서 협대역과 확대역 조건간에 20%의 명료도 차이를 나타내었다. 또한, 비교 라우드니스 레벨 조정실험의 결과, 협대역과 확대역 사이의 평균 라우드니스 레벨 차이가 약 3.4dB (A)로 나타났는데, 이 결과는 국내 확대역 전화의 수화음량적격 설정에 지침으로 활용할 것이다.

• 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.37 no.3
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• pp.147-155
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• 2018

In this paper, we tried to find out sound quality metrics to express discomfort of overload excavator noise and to develop sound quality indexes through multiple regression analysis by using them. For this purpose, the interior noise of cabin under overload condition was recorded for six excavator models with different noise properties and Jury test was carried out by PCM (Paired Comparison Method) and MEM (Magnitude Estimation Method). Jury test result with low consistency was classified into two groups with different preference tendencies by cluster analysis and multiple regression analysis was conducted in order to find out which sound quality metrics have significant effects on discomfort(low preference). As a result, we figured out that the sound quality metrics to express the discomfort were the partial loudness (= $PN_{10Bark}$) between 0 and 10 Bark in case of group1 and the difference between engine noise(= $dB_{EG}$) and hydraulic system noise ($dB_1$) in case of group2. Using the results of preference ranking and tendency analysis of PCM followed by the correlation analysis between PCM and MEM, the more reliable results were adopted by excluding the data with low consistency obtained from Jury test via MEM.