Hiroshi Furuya

Arrival direction of late sound and listener envelopment

Abstract The purpose of this study is to investigate the relation between the arrival direction of late sound and perceived listener envelopment (LEV). In this paper, two kinds of psychological experiments are conducted with three-dimensional simulated sound fields in an anechoic room. Firstly, the effect of late energy arriving from four fundamental directions on perceived LEV is individually investigated. The results show that the lateral sound level gives the highest correlation with LEV, while late sound arriving from overhead and behind the listener also correlates very strongly with LEV. Secondly, whether or not the different sound fields with a constant level of late lateral energy lead to significant differences in perceived LEV is examined. The results clearly indicate that LEV is significantly distinguished due to the late sound having non-lateral components. From these experiments, it is concluded that not only the late lateral sound, but also the late sound from other directions, such as overhead, back and frontal, contributes to LEV to a greater or lesser degree.

Three dimensional representation method for a public indoor soundscape with multiple sound sources

The author has been investigating an evaluation method of a reproduced sound such as paging sound, background music and so on in a public space. The current acoustical descriptors for an evaluation of such sounds, which are played to deliver information and attention to the people, have a difficulty to apply to multiple sounds environment. This report describes a new evaluation method which utilizes drawing an indoor soundscape with multiple sounds from listening experience, based on major aural impressions such as Loudness, Timbre, Apparent Sound Source Width, horizontal and vertical Sound Localization, Distance Perception, and Perspicuity, “KIWADACHI”. This will be applied to describe the Indoor Sound Environmental Character with multiple sound sources. The evaluation tests with this tool are carried out in the indoor sound environments of a retail shop, regarding aural impression of Perspicuity for the sound reproduction. And the results of both the subjective representation in the indoor sound environ...

Comparison of sound fields in rooms computed by finite‐element method and by cone beam method

Sound fields in realistic rooms were simulated by different kinds of computational methods, and comparisons were conducted. One is based on the wave acoustics and the other is based on the geometrical acoustics, i.e., the finite‐element method (FEM) and the conical beam method (CBM). As for the software applied here, the authors have developed their own FEM code, namely LsFE‐SFA, to conduct FEM computations, and they employed commercial software, i.e. raynoise, to conduct CBM computations. First, theoretical basis of LsFE‐SFA was given briefly. Next, sound‐pressure distributions in a reverberation room with the volume of 165 cubic meters were computed by both methods to compare the agreement with measured sound‐pressure levels. The boundary conditions due to the sound absorption were changed to examine the relation between the absorbent condition and the agreements. The agreement between FEM and measurement were found to be better throughout the examination. Next, both FEM and CBM were applied onto the an...

An acoustical design criterion for balcony configuration in auditoria. I. Acoustical characteristics measured under the balcony and the effects on auditory envelopment

The object of this study is to make clear the relation between the shape of balcony and acoustical properties under the overhang, and to derive a design criterion for balcony configuration in auditoria. On the assumption that a physical change of the sound field caused by building a balcony would be primarily a reduction of the energy of early reflections from upside, directional characteristics of early reflections were measured in auditoria both with and without a balcony, and the subjective effect of reflections arriving from upside on auditory envelopment was psycho‐ acoustically examined. First, the results of measurement showed that the ratio of the vertical component to total early reflection energy ERV was very small under the overhang. That is a peculiarity of the sound field under the balcony. Next, the results of a series of psychoacoustical experiments showed that auditory envelopment became weaker as ERV decreased when lateral energy fraction was constant. They suggested that the lack of earl...

An acoustical design criterion for balcony configuration in auditoria. II. A consideration on the directional characteristics of early reflections by computer simulation

The object of this study is to make clear the relation between the shape of balcony and acoustical properties under the overhang, and to derive a design criterion for balcony configuration in auditoria. Impulse responses were calculated in models of auditoria by means of computer simulation based on geometrical acoustics when the depth and the height of balcony opening were varied. The directional characteristics of early reflections were examined in order to evaluate the lack of auditory envelopment, which was often perceived under the overhang. As a result, it was found that the ratio of the vertical component to total early reflection energy ERV was abruptly reduced under the balcony in comparison with that in the main orchestra and was closely related to the balcony index of d/h through the regression expression, where d/h was geometrically defined by the positions of sound source, receiving point, and balcony edge. Applying the difference limen of ERV to this relation, the maximum limit ofd /h, withi...