Acoustical Science and Technology
Online ISSN : 1347-5177
Print ISSN : 1346-3969
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Volume 29 , Issue 4
Showing 1-8 articles out of 8 articles from the selected issue
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INVITED REVIEW
  • J. Stephen Downie
    Volume 29 (2008) Issue 4 Pages 247-255
    Released: July 01, 2008
    JOURNALS FREE ACCESS
    The Music Information Retrieval Evaluation eXchange (MIREX) is the community-based framework for the formal evaluation of Music Information Retrieval (MIR) systems and algorithms. By looking at the background, structure, challenges, and contributions of MIREX this paper provides some insights into the world of MIR research. Because MIREX tasks are defined by the community they reflect the interests, techniques, and research paradigms of the community as a whole. Both MIREX and MIR have a strong bias toward audio-based approaches as most MIR researchers have strengths in signal processing. Spectral-based approaches to MIR tasks have led to advancements in the MIR field but they now appear to be reaching their limits of effectiveness. This limitation is called the “glass ceiling” problem and the MIREX results data support its existence. The post-hoc analyses of MIREX results data indicate that there are groups of systems that perform equally well within various MIR tasks. There are many challenges facing MIREX and MIR research most of which have their root causes in the intellectual property issues surrounding music. The current inability of researchers to test their approaches against the MIREX test collections outside the annual MIREX cycle is hindering the rapid development of improved MIR systems.
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PAPERS
  • Shinichi Sakamoto, Hiroshi Nagatomo, Ayumi Ushiyama, Hideki Tachibana
    Volume 29 (2008) Issue 4 Pages 256-265
    Released: July 01, 2008
    JOURNALS FREE ACCESS
    Impulse responses in a hall were calculated by the finite-difference time-domain (FDTD) method, and typical room acoustic parameters were obtained from the responses. The calculated parameters were compared with those actually measured in the hall. In the FDTD calculation, the impedance boundary condition was modeled by an equivalent mechanical system comprising masses, springs, and dampers. To calculate the impulse responses, the normal acoustic impedance of the interior finishing materials of the various surfaces in the hall were measured by applying the impedance-tube method, and the model of the room boundary condition was determined for the respective parts. A comparison between the calculated and measured values showed that the values of reverberation time RT, definition D50, clarity C80, and center time Ts were in good agreement in the middle-frequency bands. However, in low-frequency bands, large discrepancies were observed because of the difficulties in determining and modeling the boundary conditions.
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  • Noriyuki Takahashi, Minoru Tsuzaki
    Volume 29 (2008) Issue 4 Pages 266-273
    Released: July 01, 2008
    JOURNALS FREE ACCESS
    To investigate the features of proficiency in musical performance, we focused on the role of auditory feedback in piano performance and measured its effects in both highly and less-trained pianist groups. In the first experiments, two groups played well-learned pieces under an auditory-feedback condition (performing with sound) as well as no-auditory-feedback condition (performing without sound). The availability of auditory feedback produced no significant differences. In the second experiment, the effectiveness of auditory feedback in the practice stage was investigated. The results revealed that in the practice stage, the less-trained group was more dependent on auditory feedback for controlling the dynamics and agogics than the highly trained group. These results suggest that some performance aspects improved by auditory feedback shifts based on performer skill levels.
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  • Daisuke Koyama, Kentaro Nakamura, Sadayuki Ueha, Hisanori Takahashi, K ...
    Volume 29 (2008) Issue 4 Pages 274-282
    Released: July 01, 2008
    JOURNALS FREE ACCESS
    Here we propose a novel measuring method of the liquid level in a water tank using the flexural vibration in a rod. With changing the water level, the frequency response of the vibrating rod is also changed due to the change of its radiation impedance. The flexural vibration along the rod can be generated by PZT elements attached on the end of the rod. The size of the vibrating rod and PZT elements were determined via the finite element analysis (FEA) so as to maximize the vibration displacement amplitude of the rod. In the FEA model considering the acoustic radiation of the vibrating rod in the cylinder, the frequency responses of the vibrating rod were calculated with changing the water level. The experiments were carried out with several configurations designed by the FEA. By sweeping the driving frequency from 5 to 7 kHz, the frequency characteristics of the vibrating rod could be obtained, and the experimental results showed good agreements with the calculated result by FEA. The frequency responses of the rod with several water levels were measured, and it was found that the water level could be estimated uniquely in the water level range of 0 to 1,550 mm.
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  • Yasushi Suzuki, Ken’iti Kido
    Volume 29 (2008) Issue 4 Pages 283-290
    Released: July 01, 2008
    JOURNALS FREE ACCESS
    A new microphone, which uses the optical total reflection on the boundary surface between glass and air, has been proposed. The intensity of reflected light changes by the sound pressure, as the fluctuation of air density due to sound changes the refractive index of air and the change in the refractive index changes the angle of total reflection. The sound pressure can be measured as the change in the intensity of reflected light. In this paper we investigate theoretically the sound pressure sensitivity of the proposed microphone in certain types of the shape of curved boundary surface. As the sensitivity can be improved considerably by employing a plane wave light source, such as laser light, and the curved surface with a large radius of curvature, the microphone is expected to be practically used. The microphone detects the sound pressure without mechanical vibration and can be made small, so its upper limit in the frequency range is very high in principle.
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