All issues
Volume 17 (1961)
- Issue 4 Pages 267-
- Issue 3 Pages 183-
- Issue 2 Pages 77-
- Issue 1 Pages 1-
Volume 17, Issue 1
Displaying 1-7 of 7 articles from this issue
- |<
- <
- 1
- >
- >|
-
Masayuki Matsui, Maki YamashitaArticle type: Article
1961 Volume 17 Issue 1 Pages 1-9
Published: March 30, 1961
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSAt the acoustical designing of the auditoriums, etc. , we have several sorts of ways to diffuse the sound fields in the rooms. In these researches, model tests were carried outs in an anechoic room with the Precision Sound-Energy Flux Meter to know the scattering effect of sound energy by the diffuser which is generally used. The anechoic room has a dimension of 3. 2×2. 9×3. 5m^3 and in it the sample of 90×90cm^2 was placed for the measurement. We used three samples; one was a flat plane, the next a polycylindrical diffuser which consisted of 3 elements of semi-cylinders of 30cm at the base and the 7. 5cm in height, and the third a triangular diffuser which consisted of 3 elements of triangles of the same size. The sound power flow density was measured along the surface of the sample with the Sound-Energy Flux Meter. The measuring frequencies were 800 c/s, 1000 c/s, 2000 c/s and 4000 c/s; the incident angles of the sound against the normal of the surface of the sample were 0°, 30° and 60°. The surface of every sample was made of hard board to be reflexible. The results are expressed as vectors whose length represent the sound power flow density, and also as angular distribution of the vectors. The scattering effect is showed quantitatively by the ratio peak/σ, where peak shows the peak value of the vector, and σ is the standard deviation of angle distribution of vectors. It is concluded from the results that the polycyrindrical diffuser has more scattering effect than the triangular one when incident angle θ is small. When θ becomes larger, this effects appears in higher frequencies.View full abstractDownload PDF (950K) -
Tomio Yoshida, Shun-ichi Iwasaki, Kenzo NagaiArticle type: Article
1961 Volume 17 Issue 1 Pages 10-17
Published: March 30, 1961
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSAn attempt has been made to show that the possibility of the "method of constant sum" as a psychological measurement in study of quality. For the purpose of comparison with the "method of paired comparison" and "method of constant sum" a typical experiment that shows the relation between the "definition" and "distance from microphone" was carried out for both methods. As a result, we could see the fact that (1) the result of method of constant sum is evaluated in a small error as order of method of paired comparison, (2) the correlation coefficient between both scales is 0. 998, (3) the errors of individuals are a small order opposite to expectation, (4) the result of consideration of internal consistency is very good. Furthermore, (5) in the field of application (the study of quality with the psychological scale) the method of constant sum has little limitation compaired with the method of paired comparison. (6) But for the subjects, special training which means the ability of numerical fractionation is required careful process.View full abstractDownload PDF (730K) -
Tomio Yoshida, Shun-ichi Iwasaki, Kenzo NagaiArticle type: Article
1961 Volume 17 Issue 1 Pages 18-26
Published: March 30, 1961
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSThe calculation for the articulation index in the case of binaural hearing has been made possible by means of a new function, namely, the loudness parameter, as follows; In the case of the monoaural hearing, the articulation index A_m and loudness N_m are given by the equation (1) and (2). A_m=1/p⎰^∞_0W_m{E(α, f)}D(f)df=A_m(α, f) (1) N_m=⎰^∞_0N_f{Z(α, f)}F(f)df=N_m(α, f) (2) And in the case of binaural hearing, the loudness N_b is given as follows N_b=2⎰^∞_0N_f{Z(α, f)}F(f)df=2N_m(α, f). (3) Assuming that the articulation index A_b in binaural hearing is expressed by following equation A_b=A_b(α, f). (4) Elimination α in equation (1) and (2), we can express A_m in terms of N_m with a new function G_m, that is A_m(f)=G_m{N_m(f)}. (5) Similarly, A_b=G_b{N_b(f)}=G_b{2N_m(f)}. (6) Assuming G_m=G_b=G, (7) we find that A_b become A_b(f)=G{2N_m(f)}=G{N_b(f)}. (8) Therefore, A_b can be calculated with A_m, N_m and new function G. This G is named by us as "loudness parameter". And with the experiments, it was proved that the assumption G_m=G_b=G is held at any case.View full abstractDownload PDF (801K) -
Tomio Yoshida, Shun-ichi Iwasaki, Kenzo NagaiArticle type: Article
1961 Volume 17 Issue 1 Pages 27-30
Published: March 30, 1961
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSAssuming A_b is expressed in term of a new function W_b, the articulation index A_b in the case of binaural hearing must be able to be calculated as in the case of monoaural hearing, as follows; A_b=1/p⎰^∞_0W_b{E(α, f)}D(f)df (1) where W_b stands for the component of articulation index of binaural hearing as W_m in the case of monoaural hearing. With the loudness parameter G described in preceding report(1), the function W_b can be estimated; Assuming that the frequency response of transmission system is flat, A_b is estimated by means of the method of loudness parameter; A_b(f)=G{2N_m(f)} (2) and on the other hand, the mean effective sensational level E(α) of this system is estimated by; E∸(α)=⎰^∞_0E(α, f)D(f)df. (3) Plotting the A_b of equation (2) with E∸, W_b is expressed in similar manner as W_m. And this theoretical result proves that it does not contradict the result of experiment.View full abstractDownload PDF (356K) -
Masaru Koyasu, Rinzi Tate, Yoshiki Ogita, Hiroshi YoshimutaArticle type: Article
1961 Volume 17 Issue 1 Pages 31-37
Published: March 30, 1961
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSSound absorption of perforated panel absorbers is characterized mainly by the resonant frequency and the maximum absorption coefficient. Usually, the resonant frequency has been calculated by the formula f_0=c/2π・√<p/l'L>, where p is the open area ratio, and l' is the effective thickness of panel and L is the depth of air space. It was found that the measured resonant frequencies became lower than those calculated by the above formula, as the depth of air space becomes larger. Thus, the following corrected formula was derived, in which the impedance of air space Z=-i(ρc/S)・cotkL was expanded in series and taken into account until the second order term. f_0=c/2π√<p/l'L+pL^2/3> This new formula agrees fairly well with experimental results. Then, the effect of the position of fibrous materials on absorption characteristics was investigated, which were inserted between the perforated panel and rigid backing. In general, the absorption coefficient becomes larger as the fibrous material comes closer to the perforated panel, but it is not so critical as the case of thin cloth.View full abstractDownload PDF (608K) -
Sakae MoritaArticle type: Article
1961 Volume 17 Issue 1 Pages 38-43
Published: March 30, 1961
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSAbout 170 octave band spectra of actual noises were gathered from the papers is "Noise Control", Vol. 3 (1957) and Vol. 4 (1958) and inspected statistically. All of their sound levels (S. L. ) were estimated by using 4 weighting responses, C (flat), B (DIN-1), A (DIN-2) and DIN-3, and also their loudness levels (L. L. ) were computed by the S. S. Stevens' method. Tab. 1 shows an example of calculations where the band pressure levels of C are given. In Fig. 1, the ordinate is the difference of the number of L. L. and S. L. . The correlation between L. L. and S. L. of B (or DIN-1) seems to be most excellent in levels higher than 70 phons, but through all ranges, that of A (DIN-2) is best. Tab. 2 shows the fluctuation or accuracy numerically. For example by A or DIN-2, L. L. (phons)=S. L. (A)(dB)+14±5 in 97% accuracy. Fig. 2 is the average octave band spectra of noises. The left figure (1) shows them in pressure levels, and the right (2) in A weighting and in sones. Generally speaking, the sound of higher levels has more higher frequency components. To determine the importance of bands, one new concept "band weight" was introduced. Weight number "2" is given to the band which has the largest level. Say it Lm. Weight number "1" is given to bands, the levels of which are smaller than Lm and larger than (Lm-10)dB. "0" is given to the remaining bands, because they contribute almost nothing to the resulting level. In case of loudness, number "2" is also given to the band of the largest sones, and "1" to bands whose number of sones are larger than the half of the maximum sone. In Tab. 1, these numbers are also tabulated, and in Fig. 4, the ordinate shows the total number of band weights of each band. It shows the degree of relative importance of bands at every response. By A and sone (loudness), bands at middle frequency region are of great predominance, showing that the accuracy of measurement of middle frequency region is most important. The figure (2) of Fig. 2 also shows the same result. As conclusion, the author wants to propose the following points: (a) The sound level measurements by sound level meter should be made only by A response; (b) The tolerances of A response of sound level meter at higher frequency up to 5000 c/s should be a little smaller than those used at present.View full abstractDownload PDF (527K) -
Yasuji Katsuki, Nobuo SugaArticle type: Article
1961 Volume 17 Issue 1 Pages 44-49
Published: March 30, 1961
Released on J-STAGE: June 02, 2017
JOURNAL FREE ACCESSThe auditory T large fibre which lies in the cord between the brain and metathoracic ganglion receives at the prothoracic ganglion not only the excitatory effect from the ipsilateral tympanic nerve, but also the inhibitory and weak excitatory effects from the contralateral one. The impulses newly evoked on this fibre are conducted to the brain and the metathoracic ganglion at the same time. The large difference in the number of impulses between the responses of a pair of the auditory T large fibres is found in the responses to a sound, the frequency of which is involved most dominantly in the stridulation of the group which is also the most effective frequency to the tympanic organ. The inhibitory effect does not operate to make the difference in threshold between a pair of T large fibres larger, but does to exaggerate the difference in the number of impulses between them. By this mechanism, the central neural network may make directional sense sharp.View full abstractDownload PDF (685K)
- |<
- <
- 1
- >
- >|