Vol.1 No.1 2008

23/76

Research paper : Development and standardization of accessible design technologies that address the needs of senior citizens (K. Kurakata, et al.)−20−Synthesiology - English edition Vol.1 No.1 (2008) the two sounds are compared [Figure 6 ②], and whether the auditory signal is audible is determined [Figure 6 ③]. If the level difference (SN ratio) of domestic sound and auditory signal sits between minimum and maximum values, the volume of the signal is considered to be readily audible. If not, volume of the signal is adjusted [Figure 6 ④]. Since it is estimated that the auditory signal will be inaudible due to interference of domestic sound if it falls below the minimum value, volume setting of the signal is raised. Conversely, if it is above the maximum level, it is unnecessarily loud, so volume setting is lowered. By going through the above procedures, it is possible to create an auditory signal set at a target volume [Figure 6 ⑤].6 Characteristic of accessible design technology development compared to conventional human science researchThe process of accessible design technology development was described using as example JIS S 0014 volume setting method for auditory signals. Here, there are two points that differ greatly from conventional human science research from the perspective of Full Research (Figure 7).First, characteristic data of great number of subjects are collected. In conventional research to clarify the mechanism of human perception or to verify the model (Type 1 Basic Research), discussions are based on measurement data on few subjects (Figure 7, Arrow ①). There, basic perception mechanism is considered common to all persons, and an “average” person is assumed. Individual differences are normally neglected as a kind of “error”.On the other hand, the subject of research in standardization of accessible design technology is individual differences in perception property including changes due to aging (Arrow ②). Therefore, data from several dozens to over 100 subjects depending on the study are collected. Individual measurement method and item are no different from the ones used in Type 1 Basic Research. However, human property research that was conventionally limited to the laboratory is extended to a design method that can be used in actual practice by analyzing statistical property of individual differences and universally applying the developed technology (Type 2 Basic Research).For this purpose, the experimental condition for collecting perception property data must be set not just for conditions limited to the lab but conditions close to the actual home. Therefore, it is necessary to study which conditions should be set and whether the setting represents the actual domestic environment. In case of auditory signals, it was necessary to collect noises that were generated in the actual domestic situation where the products were used, and extract their acoustic characteristics (Type 2 Basic Research). The analysis of domestic sound is not the objective of research, but it is an essential process in testing the validity of the volume setting method for auditory signals.The second characteristic is that emphasis was placed on simplification of the method. Accessible design technology must be an applicable method in actual product design. Design accuracy may increase by employing an intricate design method and by building a complex model of human perception function (Arrow ③). However, a complex design Fig. 6 Schematic diagram of volume setting method of auditory signal established in JIS S 0014 (modified from Reference [17]).ObjectiveWould like to add auditory signal that can be heard readily to the product・ Even with domestic sounds in the environment・ Even for elderly people with decreased hearing① Measurement of sound pressure levelCompare sound pressure levels of domestic sounds and auditory signal・ Domestic sound・ Auditory signal prototype② Comparison of sound pressure level③ JudgmentIs the auditory signal easy to hear?④ Adjust sound pressure level of auditory signal⑤ Creation of auditory signal that can be heard!one-third-octave-band level [dB]one-third-octave-band center frequency [Hz]Auditory signalInterfering soundUpper limitLower limit

※このページを正しく表示するにはFlashPlayer9以上が必要です