Acoustical Science and Technology
Online ISSN : 1347-5177
Print ISSN : 1346-3969
Search
OR
Browse
Search
Volume 23 , Issue 3
Showing 1-9 articles out of 9 articles from the selected issue
    • |<
    • <
    • 1
    • >
    • >|
PAPERS
  • Kenji Kiyohara, Ken’ichi Furuya, Yutaka Kaneda
    Type: Others
    Subject area: Others
    Volume 23 (2002) Issue 3 Pages 127-134
    Released: April 30, 2002
    JOURNALS FREE ACCESS
    A very interesting acoustical phenomenon, which we call sweeping echoes in a two-dimensional (2D) space, is described and investigated. Sweeping echoes in a three-dimensional (3D) space have recently been reported. In this paper, the regularity of reflected sound in a 2D regularly shaped space is first investigated based on number theory. The reflected pulse sound train has almost equal intervals between pulses on the squared-time axis as in a 3D space. This regularity of arrival times of the reflected pulse sounds generates sweeping echoes whose frequency increases linearly with time. Computer simulation of room acoustics shows good agreement with the theoretical results. In a practical situation, sweeping echoes were observed in a long hallway having a square section.
    View full abstract
    Download PDF (5130K)
  • Teruaki Ono, Souji Miyakoshi, Ugai Watanabe
    Type: Others
    Subject area: Others
    Volume 23 (2002) Issue 3 Pages 135-142
    Released: April 30, 2002
    JOURNALS FREE ACCESS
    Unidirectionally fiber-reinforced composites for the soundboard of musical instruments were made using glass fiber or carbon fiber and light-weighted hard polyurethane foam. The vibrational properties and frequency response characteristic of the composites were investigated by changing fibers, volume fraction of fibers and fiber distribution, and the results obtained were compared with those of Sitka spruce for soundboard. The composites, which had 5 to 6 volume percent of carbon fiber filaments distributed uniformly, exhibited almost the same acoustic property as Sitka spruce for soundboard. The results indicated that the acoustic characteristic of wood for soundboard in all audible frequency range could be mostly represented using a simple wood model composed of unidirectionally oriented fibers and porous matrix foam.
    View full abstract
    Download PDF (187K)
  • Masahiko Komatsu, Kazuya Mori, Takayuki Arai, Makiko Aoyagi, Yuji Mura ...
    Type: Others
    Subject area: Others
    Volume 23 (2002) Issue 3 Pages 143-153
    Released: April 30, 2002
    JOURNALS FREE ACCESS
    We conducted human language identification experiments using signals with reduced segmental information with Japanese and bilingual subjects. American English and Japanese excerpts from the OGI Multi-Language Telephone Speech Corpus were processed by spectral-envelope removal (SER), vowel extraction from SER (VES) and temporal-envelope modulation (TEM). The processed excerpts of speech were provided as stimuli for perceptual experiments. We calculated D indices from the subjects’ responses, ranging from -2 to +2 where positive/negative values indicate correct/incorrect responses, respectively. With the SER signal, where the spectral-envelope is eliminated, humans could still identify the languages fairly successfully. The overall D index of Japanese subjects for this signal was +1.17. With the VES signal, which retains only vowel sections of the SER signal, the D index was lower (+0.35). With the TEM signal, composed of white-noise-driven intensity envelopes from several frequency bands, the D index rose from +0.29 to +1.69 corresponding to the increasing number of bands from 1 to 4. Results varied depending on the stimulus language. Japanese and bilingual subjects scored differently from each other. These results indicate that humans can identify languages using signals with drastically reduced segmental information. The results also suggest variation due to the phonetic typologies of languages and subjects’ knowledge.
    View full abstract
    Download PDF (1905K)
TECHNICAL REPORTS
SHORT NOTE
ACOUSTICAL LETTERS
    • |<
    • <
    • 1
    • >
    • >|
feedback
Top