Abstract

In the present study, improving acoustical characteristics of a Gothic cathedral (Myeong-dong Cathedral, which is the first built Western Gothic-style architecture in Korea) using simple public address system were investigated. Acoustical measurements were conducted at 11 selected points inside the cathedral and seven acoustical parameters were calculated: sound pressure level (SPL): 64.6 dBA (the measurement value with regard to the omni-directional speaker sound source), 74.5 dBA (the measurement value with regard to the public address speaker sound source), early decay time (EDT): 4.04 s, 3.76 s, reverberation time (RT60 ): 3.58 s, 3.89 s, clarity (C80 ): −6.2 dB, −2.8 dB, definition (D50 ): 18%, 29%, initial time delay gap (ITDG): 47 ms, 23 ms, and rapid speech transmission index (RASTI): 32%, 42%. Parameters showed that the acoustical characteristics of a typical Gothic cathedral include rich reverberation and diffusive sound fields. Meanwhile, there was improved speech intelligibility when using simple public address system. Based on subjective evaluation, there was overall satisfaction with voice and music recognition and the highest satisfaction with clarity with respect to voice recognition and with reverberation with respect to music recognition. This is a good solution of optimized acoustic environment through harmony between natural reverberation and reinforced clarity using simple public address system.

Abstract

In May 2000, the Swedish code governing the conduct of drivers at marked crosswalks became stricter with the intent to improve safety and mobility for pedestrians. A crash analysis based on a macro study of all of Sweden suggests that the injury risk in marked, not reconstructed, crosswalks increased by 27% for pedestrians and 19% for bicyclists. The reason for this may be that pedestrians get a false sense of safety with the new code. Reconstructions aiming at lowering speeds are indeed needed for the change of code to be positive. The 90-percentile speed should not exceed 30 km/h or safety will deteriorate."br/""br/"However, low speed by itself may not guarantee optimal safety. Safety can be further improved at sites, which already have been reconstructed to ensure low speeds. Results based on field data collected at sites close to schools in Malmö, Trollhättan and Borås in Sweden, and in-depth studies and other analyses of Finnish and Swedish police-reported crashes, suggest that safety of children and elderly is further improved at sites where visibility, orientation and clarity are sufficient. Also, marking crosswalks may increase yield rates (expected improvement 6%) towards pedestrians; and speed cushions situated at a longer distance from the marked crosswalk increase yield rates towards pedestrians and cyclists compared to speed cushions closer by.