Kyushu University Academic Staff Educational and Research Activities Database
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Kazuhiko Kawahara Last modified date:2018.11.30

Assistant Professor / Sound Culture / Art Management
Department of Communication Design Science
Faculty of Design


Graduate School
Undergraduate School


E-Mail
Homepage
http://www.design.kyushu-u.ac.jp/~kawahara/
web page of Kawahara .
Academic Degree
Ph.D. in Design
Field of Specialization
Performance Evaluation of Acoustic Engineering System
Outline Activities
Loudspeaker Performance Evaluation:

Distributed mode loudspeaker(DML), a new class of transducer, use
bending wave of diaphragm to radiate sound.
Its radiation characteristics
is said essensially diffrent from conventional loudspeakers'.
we are trying to evaluate the performance by measuring sound intensity dirtribution in near-field of
a distributed mode loudspeaker. And we made a comparison with
sound intensity dirtribution of conventional loudspeakers.
In a case of DML, at lower frequencies, complex distribution of
mean sound intensity was observed. It looked like the distribution of interfered sound field.
And it showed the diffrence from that of conventional loudspeaker.
Research
Research Interests
  • Applause data transfer for realistic live viewing via network
    keyword : Network Audio, Realty Live Viewing
    2014.04.
  • Curriculum development of Technical Listening Traing
    keyword : Ear training, Education in Acoustic
    1990.04~2018.05.
  • Performance evaluation of Acoustic Engineering System
    keyword : Acoustic system, Transducers, Performance evaluation
    2001.04Performance evaluation of Acoustic Systems, electro-acoustic transducers.
Academic Activities
Papers
1. Kazuhiko Kawahara, Masayuki Takada, Shin-ichiro Iwamiya, Transferring technical listening training curriculum at the Department of Acoustic Design, Kyushu University, to a corporation in the acoustics industry, Acoustical Science and Technology, 37, 4, 157-164, 2016.07, Technical listening training (TLT) is a systematic training program designed to improve auditory sensitivity. TLT consists of discrimination and identification tasks for a wide variety of acoustic features, e.g., frequency, sound pressure level, and spectrum pattern. To improve the auditory sensitivity of employees in a corporation in the acoustics industry, the TLT curriculum at the Department of Acoustic Design, Kyushu University (KU), was transferred to the corporation as part of a corporate education program. An initial 5-day trial course was carried out by the KU staff to demonstrate the process of KU-style TLT and its effectiveness to the corporate staff. After the creation of a TLT control system and training room, a second trial 11-day course was jointly carried out by KU and the corporate staff as a simulation of the TLT course in the corporation. Participants in the trials were engineers in the corporation. Through the TLT trials, they improved their auditory sensitivity and their understanding of the relationship between acoustic properties and auditory attributes. They recognized the importance of the systematic listening experiences provided by TLT. Through these two trials, the corporate staff gained understanding of the TLT curriculum. Therefore, the corporation has begun running the TLT curriculum smoothly and successfully..
2. Kazuhiko Kawahara, Masayuki Takada, Shin-ichiro Iwamiya, (ACOUSTICAL LETTER)Training course for instructors of Technical Listening Training, Acoustical Science and Technology, 37, 4, 185-186, 2016.07.
3. Customized System for Technical Listening Training at Department of Acoustic Design, Kyushu University.
4. Introduction of "Technical Listening Training" as the First Class of the Specialized Curriculm of Department of Acoustic Design.
5. KIM KIHONG, Kazuhiko Kawahara, Shin-ichiro Iwamiya, (Acoustical Letter)Case study of acoustic education for Korean music majors, Acoustical Science and Technology, 35, 1, 62-65, 2014.01.
Works, Software and Database
1. .
Presentations
1. The evaluation of APRICOT system for high-realistic live viewing.
2. Moe Nishikawa, Kazuhiko Kawahara, Yutaka Kamamoto, Akiho Fujimori, Akira Omoto, Takehiro Moriya, Extraction of Applause from a Sound Field for Ambient Transmission in a Live Viewing System, 2017 IEEE 6th Global Conference on Consumer Electronics (GCCE2017) (pp.235-237 ), 2017.10, Commercial audio visual transmission such as live viewing is getting popular. Authors have proposed method of reality enhancement. We have presented applause sound transmission from the viewing site to the live hall. This paper describes the applause sound extraction method for automation of applause sound transmission, and the simulation experiment using the sound source recorded in actual live to assess the extraction performance. We used adaptive filter to emphasize applause sounds and extract them by using signal amplitude information. The experimental evaluation showed that the applause sound was almost correctly extracted by the performance sound source under various conditions..
3. Sungyoung Kim,, Jason Corey, Kazuhiko Kawahara, Doyuen Ko, Sean Olive, Timothy Ryan, Towards the New Horizon of Technical Ear Training, 143rd Audio Engineering Society Convention, New York, 2017.10, [URL], Recently, various technical ear-training programs have been introduced to audio and acoustic engineering communities. In the previous workshops, the panels have discussed necessary features and methods for efficient and effective training (AES131, 132, and 141). The current workshop aims to (1) let workshop attendees experience and compare the characteristic functions of various ear-training programs through hands-on demonstrations by the panelists, and (2) discuss the latest development trends and future applications. While the workshop locally aims to provide the attendees with chance to experience theoretical and empirical matters of ear training programs around the world, it also globally aims to consider the importance of “listening” in the current video-oriented society..
4. What can we make kids to explore in the anechoic chamber?.
5. Extraction of Applause from a Sound Field for Ambient Transmission in a Live Viewing System.
6. The evaluation of guessing the number of applauding people for applause sound synthesis..
7. Pilot study of applause detection for applause and handclap feedback on live viewing..
8. A directional microphone application to Applause and Clapping Reproduction System for Live Viewing.
9. Kazuhiko Kawahara, Masayuki Takada, Shin-ichiro Iwamiya, TECHNICAL LISTENING TRAINING AS AN ADVANCED ACOUSTIC EDUCATION PROGRAM, Youngnam Kyushu Joint Conference on Acoustics 2017 (J2), 2017.02.
10. Comparison and investigation of sound field isotropy with various measurement systems.
11. Kazuhiko Kawahara, Masayuki Takada, Shin-ichiro Iwamiya, Advanced Technical Listening Training Program at Kyushu University, 5th joint meeting of the Acoustical Society of America and the Acoustical Society of Japan, 2016.11, This presentation introduces the Advanced Technical Listening Training (TLT) program at Kyushu University. TLT is a systematic training program designed to improve auditory sensitivity; it consists of discrimination and identification tasks for a wide variety of acoustic features (e.g., frequency, sound pressure level, and spectrum pattern). The TLT II class (i.e., the advanced TLT program) provides training in identification of reverberation time, quantization bit depth, mixing level balance, and spectral slope of harmonic tones. TLT facilitates improved understanding of acoustic theory and phenomena, and psychoacoustics..
12. Kazuhiko Kawahara, Akiho Fujimori, Yutaka Kamamoto, Akira Omoto, Takehiro Moriya, Implementation and demonstration of applause and handclapping feedback system for live viewing(e-Brief 299), Audio Engineering Society 141st Internatinal Convention, Los Angeles 2016, 2016.10, Recent progress of network capacity enables real-time distribution of high-quality content of multimedia contents. This paper reports on our attempt to transmit the applause and hand-clapping in music concerts. We built a system that has an efficient implementation scheme for low-delay coding of applause and hand-clapping sounds. The system relayed applause and hand-clapping by viewers back to the performance site to provide these sounds in a synthesized and simulated manner. With this system, we conducted an experimental concert using a network distributed site. We observed some interactions between the performers and the receiver site audience.
Responses to our questionnaire distributed to the audience and performers also confirmed that applause and hand-clapping feedback were effective for improving the sense of unity established in live viewings..
13. Sungyoung Kim,, Mark Bassett, Jason Corey, Kazuhiko Kawahara, Sean Olive, Critical Listening: Ear Training in Audio Education, 141st Audio Engineering Society Convention, 2016.10, [URL], Considering the interests and growth of ear training in the audio communities, it is timely and important to have a chance to share and discuss the opinions from the experts about necessary features and methods that assist trainees in acquiring the critical listening ability with efficiency, both for personal and group training.

The current workshop aims to let workshop attendees experience and compare the characteristic functions of various ear-training programs through hands-on demonstrations by the panelists. While the workshop locally aims to provide the attendees with chance to experience theoretical and empirical matters of ear training programs around the world, it also globally aims to consider the importance of “listening” in the current video-oriented society..
14. Design and Implementation of Applause and Clapping Reproduction System for Live Viewing.
15. Pilot study of applause and handclap feedback on live viewing..
16. Education for acoustic engineers and sound designers in Department of Acoustic Design, Kyushu University..
17. Case study of Electro-Acoustic Education in Acoustic Experiments at the Department of Acoustic Design, Kyushu University.
18. Pilot study of applause sound generator depending on the listening environment.
19. Investigation of active diffusibility control in enclosed sound field
-Control of acoustic mode in small sized reverberation chamber
and possibility of multi-channel reproduction system-.
20. Kosuke Goto, Kazuhiko Kawahara, Design and Performance Evaluation of a Stereo Sound Reproduction System with a Complementary Distributed Mode Loudspeaker, 2015 IEEE 4th Global Conference on Consumer Electronics (GCCE) (pp. 34-37), 2015.10, This paper proposes an effective method to use a Distributed Mode Loudspeaker (DML). DMLs are loudspeakers with strong diffusion properties. In this paper, we proposed a sound reproduction system with a DML. The sound field generated by the proposed reproduction system is measured by the index of diffusivity. As a result, it is concluded that the sound field generated by the proposed reproduction system has a higher diffusivity when compared with a conventional reproduction system. The proposed system also demonstrates strong results with respect to the influence of the chamber's acoustic boundary on sound quality..
21. Basic study for realization of an active reverberation box. - Effect of location and dimension of sound sources on the generated sound field -.
22. Kazuhiko Kawahara, Yutaka Kamamoto, Akira Omoto, Takehiro Moriya, Evaluation of the Low-Delay Coding of Applause and Hand-Clapping Sounds Caused by Music Appreciation(#9225), Audio Engineering Society 138th Internatinal Convention Warsaw 2015, 2015.05, Recently, the improvement of network resources enables us to distribute the contents in real-time. This paper presents the low-delay coding of applause sound and hand-clapping sound with less parameters by means of synthesizing these sounds at the receiver site. We found that a number of people clapping their hands were corresponding to a sound volume of applause. In other words, no one considers who is clapping. Additionally, on the hand-clapping sound, the time interval of clapping also should be important. Based on such information, preliminary experiments confirm that our approach, which synthesize applause and hand-clapping sound from a few parameters, successfully generates natural applause and hand-clapping sounds..
23. Vibro-acousitic analysis of a Distributed Mode Loudspeakers introducing viscoelastic properties in its support condition.
24. A study on changes of impressions by introducing “Equalization” in sound field reproduction system.
25. Michiaki Takahashi, Kazuhiko Kawahara, Akira Omoto, COMPARISON OF HOWLING MARGIN IN VARIABLE REFLECTION ACOUSTIC WALL SYSTEM WITH SEVERAL ADAPTIVE ALGORITHMS, Kyushu-Youngnam Joint Conference on Acoustics 2015, 2015.01, To change reverberation in enclosed space for various purposes, Variable Reflection Acoustic Wall System, VRAWS has been proposed. The VRAWS is consisted with microphone, absorbing material and loudspeakers located just behind the absorbing material. Incident sound wave to the system is firstly absorbed by absorbing material. At the same time, the microphone mounted in front of absorbing material detects the sound. The detected sound is then passed some signal processor such as reverb effect or equalizer, and re-radiated by the loudspeakers behind the absorbing material. This system is sound reinforce system with closely located microphone, so the performance is limited by the howling margin. To improve the howling margin, adaptive howling canceller with Least Mean Square (LMS)-type echo canceller is firstly introduced. This echo cancel filter is basically disturbed by so-called double talk. Also, simplified fast transversal filter(SFTF) for howling cancellation is implemented with Digital Signal Processor. The SFTF reduces the computational complexity compared with recursive Least square algorithm (RLS). The performances of several adaptive filters used in the howling canceller are compared with several types of VRAWS by experiment..
26. Technical Listening Training as an acoustic education for freshmen. -System design and evaluation from questionnaire-.
27. Kazuhiko Kawahara, Impression measurement of three different types of loudspeakers’ sound field, 2014 IEEE 3rd Global Conference on Consumer Electronics (GCCE) (pp.517-518), 2014.10, Recently, some new implementations of panel form loudspeakers were proposed. Some of them have quite different radiation characteristics compared with dynamic loudspeakers. Especially Distributed Mode Loudspeaker (DML) has diffused property of radiation. But the subjective impression of this property was needed to investigate. In this paper, 39 adjective and adjective phrases were selected for impression measurement. Two of dynamic loudspeaker models, a DML and an electrostatic loudspeaker were used for this impression measurement. As a result of median test, DML gave the impression of wider sound fields, spatial sense, depth sense and blurred sound fields..
28. Kazuhiko Kawahara, Shin-ichiro Iwamiya, Masayuki Takada, (Invited)Educational Aim and Uniqueness of Technical Listening Training(PJ08-3), 7th Forum Acousticum, (P.1-4), 2014.09, This paper describes the educational aim and uniqueness of Technical Listening Training. Technical Listening Training is a systematic training program to improve the listening ability as a sound professional. This training has been developed in the Department of Acoustic Design, School of Design of Kyushu University. The educational aim of technical listening training is to encourage students to listen as a sound/acoustic professional. The listening ability as a sound professional is constructed by the following three abilities: the ability to discriminate between different sounds, the ability to correlate the auditory difference with the physical properties of sounds, and the ability to imagine the proper sounds when given the acoustic properties of the sounds. The educational uniqueness is the fact that trainings have been carried out as a class of the university curriculum. The class also includes lectures on basic acoustics and audio engineering related to training menus. Through trainings, in addition to improving the listening ability, trainees can share their listening experiences. The shared experience among trainees improves their ability to express their impression with coherent words.
.
29. A study of variable acoustic wall system :In case of distributed mode loudspeakers..
30. Fundamental evaluation for the low-delay coding of applause and hand-clapping sounds caused by
music appreciation.
31. Vibro-acoustic analysis of Distributed Mode Loudspeaker..
32. DAW application to ear training..
33. A study on the relationship between TLT subject’s performance and their backgrounds.
34. On curriculum of technical listening training..
35. Methods for analyzing vibration characteristics of Distributed Mode Loudspeakers, IEICE Technical Report EA2013-85, pp. 101-106.
36. Sungyoung Kim, Timothy J . Ryan, Jason Corey, Doyuen Ko, Kazuhiko Kawahara, Towards a Systematic Ear - Training Curriculum: Effective and Efficient Learning in Audio Education, AES 50th Conference—Audio Education, 2013.07, Ear Training の有効性を議論するとともに,本学で行っている,聴能形成のカリキュラムを紹介し,その有効性を示した。カリキュラム構成のコンセプトを示すとともに,スピーカ聴取訓練とイヤホン聴取訓練の利点欠点を整理し,議論した。本学は,スピーカ聴取訓練をおこなっており,そのコンセプトは,音を音場を聴き,音響現象を体験することにあることを主張した。.
37. Kazuhiko Kawahara, Masayuki Takada, Shin-ichiro Iwamiya, Effectiveness of technical listening training in Department of Acoustic Design
of Kyushu University, international congress on Acoustics 2013(3aED8), 2013.06, What is the professional listening? Sound/Acoustic Professionals listening categorized into three phases. The ability to discriminate between different sounds. The ability to correlate the auditory difference with the physical properties of sounds. And the ability to imagine the proper sounds when given the acoustic properties of the sounds. The ability can be trained through listening training. Through trainings, trainees can share their auditory experience. The shared experience reinforces trainees to express their auditory impression with coherent words. And the use of coherent words supports smooth communication in their group. This word coherency is also the professional listening ability. In this paper, as a listening training, Technical Listening Training in Kyushu University was described. And we evaluated learning effects of training
with average correct answer ratio among trainees. Trends of increasing correct answer ratio with training times were observed. We could show the effects of Technical Listening Training..
38. Case study of Demonstration "Loudspeaker mechanism and measurement" for high school students
-- From "Acoustics and visual communication experiments for high school students" in Kyushu University --.
39. A report of acoustic education for fashion design major students.
40. Report of acoustic education for Korean students of music major: A case study of the 2011 school in
college of arts & graduate school of arts of Dong-A university..
41. Improvement of Speech Intelligibilty in a Concert Hall.
42. Sound Field Reproduction System Based on Variable Reflection Acoustic Wall System..
43. Acoustic response analysis of Distributed Mode Loudspeaker by the vibro-acoustic analysis..
44. Case study of introduction and planning of “2003 Spring Exibition: Sound and Technology” at The Saga Pref. Space & Science Museum.
45. A study on active noise control by multipole control sources..
46. Multipole End-Fire Loudspeaker Array Based on Spherical Harmonic Expansion..
47. Sound radiation synthesis by using multipole expression of spherical harmonic expansion..
48. Modal analysis and generated sound field simulation of a vibration panel. In case of in a free sound field an d in a rectangular enclosure
, IEICE Technical Report EA2010-89, pp.31-36.
49. The first step to frequency analysis..
50. Loudspeaker characteristic evaluation with cross correlation of inter radiation directional impulse responses.
51. Technology transfer of technical listening training education to employees of an acoustic related campany
-- case study i case of technology transter to Yamaha corporation --.
52. Technology transfer of technical listening training education to employees of an acoustic related campany
-- case study i case of technology transter to Yamaha corporation --.
53. An introduction of "Techincal Listening Training" to employees in acoustic related company.
54. Loudspeaker characteristic evaluation with coherent distance in reverberation room.
55. Loudspeaker characteristic evaluation with coherent distance in reverberation room.
56. Case study of acoustic education in
``Acoustics and visual communication experiments for high school students''.
57. Recent technologies for loudspeakers, Distributed mode panel loudspeaker.
Membership in Academic Society
  • Acoustical Society of Japan
  • The Insittute of Electronics, Information and Communication Engineers
Educational
Other Educational Activities
  • 2000.01.