教員・研究者紹介

西村 公伸

西村 公伸
教授
所属 工学部 機械工学科
システム工学研究科
学位 博士(工学)
専門 音響・音響機器・振動工学・環境振動
ジャンル 科学・技術/新技術
コメント 騒音・振動の制御や雑音対策などを扱っており、オーディオ機器の雑音低減技術、楽器の音響特性評価・設計、遮音・吸音システムの特性評価・設計、さらに公害振動制御に関する指導を行っている。
リサーチマップ https://researchmap.jp/Gasparo-da-Salo

高校生の方へ 研究室紹介

音のある環境や音質の改善を現象・心理面からアプローチ。

オーディオや楽器の音質改善、遮音・吸音性に優れた室内音響などがテーマ。振動現象などの研究で音と機械工学の関わりを探究し、特許出願の開発にも関わる。

学歴/経歴

学歴

  • - 1981年
    広島大学 工学研究科
  • - 1981年
    広島大学 Graduate School of Engineering
  • - 1979年
    山口大学 工学部
  • - 1979年
    山口大学 Faculty of Engineering

経歴

  • 2003年4月 - 現在
    近畿大学 工学部 機械工学科 教授
  • 1994年4月 - 2003年3月
    近畿大学工学部 助教授 Faculty of Engineering
  • 1994年 - 2002年
    Associate Professor, Faculty of Engineering,

  • Kinki University

研究活動情報

研究分野

  • ものづくり技術(機械・電気電子・化学工学), 電子デバイス、電子機器
  • 社会基盤(土木・建築・防災), 建築環境、建築設備
  • 環境・農学, 環境動態解析

研究キーワード

オーディオインシュレータ, オーディオ機器, 音質改善, 騒音・振動, 環境騒音評価, Sound and vibration, Evaluation of Environmental Noise

論文

  1. A STUDY ON TIMBRE AND SOUND QUALITY OF AN ELECTRIC GUITAR BY SELECTION OF MATERIAL AROUND PICKUP
    Kiminobu Nishimura; Keisuke Nishimura
    PROCEEDINGS OF THE 23RD INTERNATIONAL CONGRESS ON SOUND AND VIBRATION: FROM ANCIENT TO MODERN ACOUSTICS  2016年  [査読有り]
  2. Two Methodology-Trials Using Higher Order Correlation for Reverberation Measurement of Noisy Acoustic Room
    Kiminobu Nishimura; Mitsuo Ohta
    IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences  E87-A  (3)  598-604  2004年3月 
  3. A stochastic estimation of non-stationary sound signals based on elimination of background noise through vibration measurement
    Mitsuo Ohta; Kiminobu Nishimura
    IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences  E83-A  (1)  158-160  2000年  [査読有り]

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講演・口頭発表等

  1. 自動車ロードノイズ帯の振動絶縁効果を持つサスペンションの結合方法Ⅰ , 村上智哉 , 日本機械学会中国四国支部第57期総会・講演会 , 2019年3月7日
  2. オーディオ再生音の音像定位制御における超音波の影響 , 玉川謙一郎 , 日本機械学会中国四国支部第57期総会・講演会 , 2019年3月7日
  3. 四端子定数を用いた円錐型オーディオ用インシュレータの振動伝達特性の解析 , 喜多雅英 , 日本音響学会2019年春季研究発表会 , 2019年3月5日

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MISC

  1. Theoretical and experimental study on vibration transmission of an audio-base formed into solid conical horn , Kiminobu Nishimutra; Kenji Manpuku; Masahide Kita , 25th International Congress on Sound and Vibration 2018, ICSV 2018: Hiroshima Calling , 3 , 1762 , 1769 , 2018年
    概要:Vibration caused on audio equipment seems to induce some problems on reproduced sound quality as electrical noise as result of interaction with geomagnetism. But its mechanism how to convert the vibration on audio equipment into electrical noise is unknown. On the other hand, many kinds of methods to reduce vibration on audio equipment are introduced in actual new product according to the grade, but after purchase of audio equipment, how a consumer can deal with those noises? To deal reproduced sound of audio-equipment, audio-base is widely used among audio mania. Though, there are many kinds of audio-bases on the market and their effects seem not always better one for reproduced sound quality, because of uncertain mechanism of audio-base. As an experimental study, we confirmed that the decrease in vibration on audio equipment is effective the decrease in noise on output signal. Furthermore, in previous study, to confirm the work of audio-base, we derived theoretical analysis of vibration transmission characteristic for exponentially shaped solid horn. In this study, as an audio-base formed into conical horn is most popular, first, we try to derive theoretical analysis of driving impedance for conical horn to describe its working mechanism. The vibration transmission characteristic is evaluated for both transmission direction from “Throat” to “Mouth” and opposite direction under excitation at “Throat” or “Mouth”. Then, the difference in transmission characteristics owing to the transmitting direction is evaluated as difference in driving impedance based on the impedance matching theory. Consequently, we could clarify that the audio-base has changing frequency point to pass through or insulate the vibration related with material and shape. This tendency is also confirmed experimentally by measuring the difference in vibration velocity between input and output surfaces of audio-base. This selective transferring characteristic will be useful to eliminate or insulate inevitable vibration.
  2. Theoretical and experimental study of vibration transmission in an exponential horn filled with solid material , Masahide Kita; Kiminobu Nishimura; Kenji Manpuku , 24th International Congress on Sound and Vibration, ICSV 2017 , 2017年
    概要:There are many kinds of audio-bases on the market and they are used for trying to improve the reproduced sound of audio equipment. On the other hand, their effects seem not always better one for reproduced sound quality, because of uncertain mechanism of audio-base on acoustic and electric signal. Furthermore, considering its usage, the working of audio-base seems to be limited to a change in the vibration state of loaded audio equipment. In previous study, we had clarified that an audio-base is effective to reduce inevitable vibration and electrical noise caused on stereophonic equipment and to improve the sound quality and summing localization under standard stereophonic representation. In this study, to describe the working of audio-base from theoretical viewpoint, first, we derived a driving impedance of exponential horn at excitation point "throat" or "mouth". Then, the difference in transmission characteristics owing to the transmitting direction is shown as difference in driving impedance based on the impedance matching theory. Consequently, we could clarified that the audio-base has alternating frequency point to passing through or to insulate the vibration related with material and shape. This tendency is also confirmed experimentally by measuring the difference in vibration velocity between input and output surfaces of audio-base.
  3. A study on noise reduction of audio equipment induced by Vibration - Effect of magnetism on polymeric solution filled in an audio-base , Masahide Kita; Kiminobu Nishimura , ICSV 2016 - 23rd International Congress on Sound and Vibration: From Ancient to Modern Acoustics , 2016年
    概要:Recently, though multi-channel audio technique provides surround representation, conventional standard stereophonic reproduction could recreate three-dimensional sound field by perfect reproduction of sound without losing any of information involved in sound source. Unfortunately, it is known that when music is reproduced by audio equipment, sound quality degrades be-cause of noise or distortion produced in equipment by various factors. One of above factors, vibration induced on equipment is remarkable one. To adjust the replay sound, various kinds of audio-bases are on the market, but their effect or work is not clarified. In the previous studies, new style of audio-base was proposed which constructed with spike installed in a cup poured with polymeric solution (e.g., Polyethylene Glycol (abbr. PEG)). When the PEG molecule in vibrates at right angles to magnetism, it will rotate and absorb the vibration energy more strongly under reinforced magnetism. On the other hand, as vibration on audio equipment causes electromagnetic induction noise, degrease in vibration becomes effective to reduce noises. In this study, to clarify the qualitative relationship between the magnetic field strength and vibration reduction, we have carried out two experiments. First, induced noise on amplifier vibrated by sinusoidal sound excitation without signal input is observed for with and without strong magnetism around audio-base. Next, to evaluate the ability of vibration reduction under strong magnetism, we observed the vibration caused on the amplifier under usual music representation. Consequently, it is clarified that the vibration and electromagnetic noise induced on amplifier can be reduced well under reinforced magnetism around audio-base. Especially, harmonic distortion is effectively about 1.5 dB by reinforced magnetism.

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産業財産権

  1. スピーカボックス , 西村 公伸, 中西忠彦 , 特許第4444782号
  2. スピーカの振動除去装置 , 西村 公伸, 伊奈龍慶 , 特許第4406698号
  3. 振動防止支持装置 , 西村 公伸, 伊奈龍慶 , 特許第3848987号

受賞

  1. 1993年, 電気学会論文発表賞B

共同研究・競争的資金等の研究課題

  1. 非定常不規則変動の分布評価における局所的非ガウス性の影響に関する研究
  2. Study on Effect of Non-Gaussian Property in a Lacally Stationary Period on Probability Distribution of Nonstationary Random Noise
  3. 振動計測に基づく機械騒音評価に関する研究

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