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Research paper : Development and standardization of accessible design technologies that address the needs of senior citizens (K. Kurakata, et al.)−18−Synthesiology - English edition Vol.1 No.1 (2008) experiment described in Section 4.3.4.2 Accommodation of interference by domestic soundThe places where users use products are varied, and environmental conditions differ greatly. Even if the sound can be heard in a quiet laboratory, if it cannot be heard in an actual use situation, an auditory signal is not appropriately designed. The desired optimal volume needed for auditory signals differs according to the acoustic characteristics such as loudness of interfering noise, structure of frequency component, and time fluctuation. However, it is practically impossible to cover all product use situations and to establish volume setting method for every noise generated. Therefore, it is necessary to simplify the acoustic characteristics of domestic sounds that may be generated in the environment in which the product is used, and create a model that can be verified.Therefore, prior to the proposal of JIS S 0014, various domestic scenes were assumed and domestic sound database JIS TR S 0001[12] that described the acoustic characteristics of typical noise generated in those scenes were compiled. The range of domestic sounds subject to measurement and the factors addressed are summarized in Figure 3.First, space that will be the subject of study was limited to indoors. Products such as cameras are used both indoors and outdoors, but measurements would increase infinitely if outdoor environment was included. Considering the fact that many consumer products are used indoors, the subjects were limited to sound generated indoors. However, even by limiting the subject indoors, there are several rooms with different noise levels in a house like living room or kitchen. Moreover, sound difference in Japanese and western style rooms could not be neglected.Volumes of the rooms differed. In a large room, the level of domestic sound differed depending on the location within the room. Therefore, in creating the database, measurements were taken in different locations of the room, and the effects were also described. Also, there were sound sources where volume greatly changed according to the manner of use such as sounds of water in the kitchen or television in the living room. For water sound, measurements were taken at several water volume levels, and for television sound, volume preferred by the elderly was measured in a separate experiment[13].As a result of the measurements, the database contained over 350 measurements data for 16 types of domestic situations. An example of analysis of domestic sound entered in JIS TR S 0001 is shown in Figure 4. In case of domestic sound, the variation in acoustic characteristic due to differences in houses could not be neglected. Therefore, the database also shows the distribution of measurement values as shown in Figure 4[14]. By using this database, it is possible to study the degree of difference of noise characteristic in each domestic situation, or the degree of variation of characteristic due to differences in houses.In general, one would imagine that the domestic sound characteristic would differ greatly if the houses were different. However, as shown in Figure 4, if limited to a single measurement situation, variation due to houses was only about 10 dB (see the interval between 5 percentile curve and 95 percentile curve in Figure 4). Rather, the characteristic difference between sound of particular measurement situation and another (for example, between water sound of sink and volume of TV in living room) was greater. Therefore, the sound of individual domestic situation was represented by frequency characteristic at 50 percentile value (see Figure 4), and it was assumed that domestic sound produced at home could be covered by selecting several typical domestic situations. Using various selected domestic sounds, auditory signal level that could be heard readily was investigated in an auditory experiment described below.Fig. 4 Example of analysis diagram of domestic sound database TR S 0001[12] (sound of washing dishes in sink).Shows the distribution of measurement values in several houses.80706050403020101251602002503154005006308001000125015002000250031504000500063008000LAeqSound pressure level (dB)1/3 octave band center frequency (Hz)95 Percentile5 Percentile25 Percentile50 Percentile75 Percentile

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