This study concerns subjective intelligibility rated with method of magnitude estimation. Rating tests were conducted for speech sound and monosyllable sound in steady broad-band noise at various levels. Relation of subjective intelligibility ratings between speech sound and monosyllable sound was investigated in relation to S/N ratios. Correlation of subjective intelligibility ratings to S/N ratios and standard errors of estimate were also calculated. As the results, subjective intellibility ratings correlated to S/N ratios in higher than 0. 91 for both sounds and standard errors of estimate were 3. 2-4. 2 dB(PSE). Subjective intelligibility of speech sound could be estimated at 3. 3 dB(PSE) lower than subjective intelligibility of monosyllable sound which could be predicted by articulation index.
There are some convenient natures in plastics for people, such as plasticity, corrosion resistance and lightness in weight so that plastics have been used in place of other materials partially or completely. Then ultrasonic plastic welding has been widely used in many kinds of fileds, because we can weld in a very short time by a simple handing without any adhesives. Usual ultrasonic plastic welding had been only for small in size, such as cosmetic vessel and toy. In recent years, however, plastics have been using for large in size, such as automotive parts and furniture so that ultrasonic plastic weiding which can be used in such size has been required. Therefore, there is need of large-sized vibration horn. However, it is difficult to manufacture this horn which satisfies the vibration conditions of ultrasonic plastic welding so that we cannot take advantage of this welding. Thus we made the assumption : if we took advantages a lot of solid oscillators which has the well-established standard of design, large-sized vibration horn would be organized. We took the vibration horn which has the large-sized cylindrical cross section for instance, designed and manufactured by way of trial. This large-sized vibration horn was excited on the longitudinal vibration mode of the large-sized cylinder by the bending vibration mode of thick disk. Reports of the analysis of the bending vibration of thick disk have apparently not been published to date so that we analysed it and that we confirmed it experimentally. Thus, we obtained one of its design instruction. From the facts described above, we may conclude that large-sized vibration horn can be organized by a lot of solid oscillators, and we think that we obtained one of the design instruction of large-sized vibration horn.