Calibration method using transfer function was developed for comparison calibration of vibration pickups in a back to back configuration. The sensitivity of a uniaxial vibra-tion pickup calibrated by this method agreed satisfactorily with that calibrated by a con-ventional sinusoidal excitation method. In the comparison calibration, best result can be obtained when reference and unknown pickups are mounted in the back to back con figuration with sensing axes parallel with the direction of motion. A mounting adaptor is necessary to mount a multiaxial vibration pickup on the reference pickup back to back. However, precision of the calibration decreases, when rocking motion of the adaptor is excited, or the adaptor deforms. Influence of the rocking motion and resonance due to the deformation has to be minimized for the precise calibration. In this paper, two methods in which a reference vibration is estimated from vibrations measured at several points of the mounting adaptor are proposed for the calibration of the multiaxial vibra-tion pickup.

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A multi-microphone sub-band selection method has been proposed for dereverberation with the assumption that the transfer function between the sound source and each micro-phone can be calibrated. In this paper, the dereverberation system is implemented for a speaker dependent word recognizer as a preprocessor. The degradation of the recog-nition performance was investigated under three reverberation conditions. The prepro-cessor is evaluated by the recognition rate of using different numbers of microphones and sub-bands. It is found, when the distance between the sound source and the microphone is about 2.65m and the reverberation times of the enclosure are 0.55, 0.68, 0.86s, the recognition rates of the reverberated speech decreased by 12.8, 13.6, 14.5%, respectively, compared with the original clean speech. The results showed that the recognition rates were improved by 11.3, 12.6, 12.3%, respectively, by introducing the dereverberation preprocessor.

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Not only surrounding noise but also the sound radiated by an equipment itself seriously affect the performance of speech recognition when one tries to make voice control system for sound radiating equipment such as a television set. In this paper, a configuration of speech recognition system for this kind of equipment is proposed. This system consists of three components; an adaptive digital filter to reduce noise radiated by the equipment, a speech candidate detector, and an isolated word recognizer. In the experiments not only white noise but also colored noise such as organ solo and male voice are used. In all cases, over 90% of correct recognition ratio is obtained even when speech level is the same as noise level.

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The results of social surveys on transportation noise in Japan were summarized. They were compared with published data in foreign countries based on the Fidell's single value of L_dn in the annoyance function which corresponded to 1/e (37 %) of highly annoyed. It was found that various kinds of response scales had been used in the past as listed in Appendix. The scales are expressed in some of different wordings. They are divided into 3 to 11 steps and the verbal descriptive labeling of steps are not always the same. Therefore, the selection of steps as highly annoyed is likely to affect the results of an-noyance response. For comparison of social survey data, it seems necessary to use the standardized annoyance scale to avoid the ambiguity in the measuring procedure of an-noyance. The expressions of an annoyance scale and steps in different languages and their translation are also important problems in the case of international comparison.

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Vibrations of piano strings struck with an elastic hammer are studied by using equivalent circuitmodels based on the impedance analogy and the mobility analogy respectively. When the tension of a piano string alone is considered, neglecting its elasticity, the string and hammer system has an analogy with an electric transmission line, the hammer being represented by an inductance and a capacitance. An analogue simulator based on the models was designed and used for the study of the string and hammer system. Various waveformes, contact times, and the maximum contact force in each case were obtained by using the simulator. The reason for the appearance of even harmonics series in a high frequency region of piano keys, clearly shown in the simulator, is ex plained;and the method of their adjustment is suggested. A velocity waveform is de terminedby the resultant of two vertical tension waveforms in the simulator. The characteristics of these waveforms are shown compared with those from an actual piano. The contact forces, from which their vertical tensions can be reduced, are calculated from the equivalent circuits. Waveforms in all the cases become very similar to damped half sinusoidal waves. The energy transmission from a hammer to a string, including its efficiency at a low-frequency region, is discussed.

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For a treatment of bone fractures there has been a locked intramedullary nailing. Since the interlocking nail is connected with the femur by screws againsthe rotational union, the interlocking nail has been drilled for the screw holes. Therefore it is required to monitor the position of the screw holes of the interlocking nail. X-ray has been con-ventionally used. In this study an efficacy of ultrasonic trans-femur imaging for moni-toring the screw holes through the femur is discussed. B-scan and C-scan imaging by pulse-echo technique are experimentally performed by using ultrasonic pulsed waves of 3.5MHz and 5.0MHz in center frequency to determine the position of the holes. In the resultant images of 3.5MHz the holes are not observed, however, in the images of 5MHz the lower intensity region which is correspondent to the hole is observed. Con-sequently, it is revealed that ultrasonic trans-femur imaging is capable of monitoring the interlocking nail.

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