Kazutoshi Fujimoto

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.

Introduction of sound material in living environment 2004 (SMILE 2004): A sound source database for educational and practical purposes

Sound sources are used in various settings of education, research, and business that are related to architectural acoustics. Especially in educational scenarios, they are very effective for students to learn theories together with the experience of listening to actual sounds related to them. Sound Material In Living Environment (SMILE 2004), a sound source database published in 2004 in DVD form (Japanese only), is the culmination of our project. SMILE 2004 is intended as a collection of sample sounds for use in lectures on architectural acoustics at universities or industrial high schools. In addition, it is useful for measurements or demonstrations for academic or practical purposes. The database contains 913 digital sound files of real sounds and impulse responses, which cover the study fields of acoustics, noise control, and soundscapes. Each sound is accompanied by such information as the 1/1 octave band sound pressure levels and a brief explanation and photographs of the situation in which the sound ...

Effect of accuracy of digital map data on predicting road traffic noise in Japan

Use of GIS for evaluating the Environmental Quality Standards for Noise is established at local authorities in Japan. A digital map on a scale of 1/2,500 is generally used. However, it has not been clarified yet whether the digital map with such a scale has an accuracy to apply for the estimation of environmental noise. A ground plan of buildings on the digital map is a roof plan, because the digital map data are made on a basis of an aerial photograph. It is feared that the noise estimated by using such a map may have some differences in the effects of buildings on the noise propagation from reality. In spite of the fact that the propagation of road traffic noise is highly affected by whether a road is visible from receiving point or not, when the roof plan is used as the floor plan, the road is sometimes visible from the receiving point on the digital map, though it is invisible in practice. The aim of this study is, therefore, to reveal the effect of accuracy of the digital map in GIS on the estimation...

Development of long-term data acquisition system of noise exposure and personal behavior for analysis of health risk: Measuring equipments

We have built a trial prototype of a long-term data acquisition system of individual noise exposure (hereafter referred to as HIKE) and have carried out technical verification of the system. HIKE consists of a noise exposure meter, a thermohygrometer, an illuminometer, and a smartphone. HIKE continuously measure LAeq,1s and global positions of subjects in daytime, and in addition environmental parameters such as atmospheric temperature, relative humidity and illumination in nighttime. The noise exposure meter should be as small and light as possible for the portability and equip longer battery-life to realize the long-term data acquisition. Global positioning system on the smartphone is utilized to detect the position of subject, and we have newly developed original software for integrating the functions of collecting, storing, and displaying all data measured on the smartphone. Wireless network is applied to connect the smartphone with other measuring equipments for convenience of long-term measurement, ...

Development of long-term data acquisition system of noise exposure and personal behavior for analysis of health risk: Preliminary studies

To investigate relationship between individual noise exposure and the effect on health, firstly we have designed a measuring equipment because commercially-available noise exposure meter adopts the averaging times of a few minutes that are longer for our purpose. Requirements of the equipment we focus on are to measure (1) intermittent characteristic of noise that include the maximum level, the number of event, and level difference between background and target noises for sleep disturbance, and (2) equivalent continuous A-weighted sound pressure levels during 24h for physiological effect. Environmental condition especially in nighttime and position where people are exposed to noise are also important parameters to be taken into consideration. In addition to the noise exposure meter, the measuring equipment developed includes thermohygrometer, illuminator and smartphone. We pursue portability and simplicity throughout the equipment. We suppose that subjects put on the noise exposure meter and the smartphon...

Development of long-term data acquisition system of noise exposure and personal behavior for analysis of health risk: Research background

Since people living in urban areas are continuously exposed to loud environmental noises for a long duration, the noise has to be treated not only as nuisance in our daily lives and adverse psychological effect but also as possible risk on health. WHO has presented an environmental noise guideline and has suggested dangers or risks on health by long-term high noise exposure, and has recently published nighttime noise guideline to prevent adverse health effect to sleep disturbance. Some research projects in EU have revealed that detailed measurement in time of individual noise exposure is needed to improve the current assessment method, instead of those based on energy-averaged value over the exposed duration to noise. It suggests necessity of short time-interval measurement of individual noise exposure as well as information when and where people are exposed to the noise. It is also necessary to measure environmental condition in nightitme, since the condition very likely disturbs our sleep and therefore ...

Sound‐absorbing material made of recycled polyester nonwovens using scrapped pieces

The authors developed polyester nonwovens (PW) that have nearly equivalent sound absorption to glass wool with similar thickness and density. Unfortunately, scraps amounting to 20% of crude polyester are generated during PW manufacturing and cutting. They must be discarded as waste materials. Therefore, the authors contrived an original recycling technique to use such scrap pieces. Sound absorption characteristics of recycled materials manufactured using this method (RPW) are inferred to differ from those of PW because of their different fiber compositions. In this study, sound absorption of RPW is measured and the following points are examined experimentally: the relationship between manufacturing processes and sound absorption of RPW; sound absorption of RPW when two kinds of scrap pieces are mixed; and effects of mixing crude materials on RPW sound absorption. Results indicate that RPW has sufficient sound absorption for practical use. Comprising scrapped pieces that have been discarded as waste, RPW a...

Sound absorbing material made of polyester nonwovens

Polyester nonwovens (PW) comprise fine fibers, similarly to glass wool (GW). Therefore, PW is expected to have high sound‐absorption capabilities. In recent years, application of PW, an entirely recyclable material, as an absorbent material has attracted much attention from the viewpoints of resource recycling and waste reduction. In some cases, manufactured PW has been used as an interior material in an actual acoustic laboratory. Reportedly, however, PW has slightly inferior sound absorption capabilities compared to GW. For wider use as a sound‐absorbing material, PW must have better sound absorption. In this study, sound absorptions of PW were measured for various fiber compositions. Specifications that engender high sound absorption capabilities were examined. Results revealed PW specifications that provide similar sound absorption as GW with similar thickness and density. The PW presented in this paper has both high sound absorption and good environmental properties. Therefore, it is useful as a soun...

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...