The authors have proposed a method of ultrasonic welding using planar vibration composed of longitudinal and torsional vibrations, and obtained higher tensile shear strength in a shorter time than by ultrasonic welding using conventional linear vibration. However, the cross tensile strength was not examined. And, the comparison of tensile shear strength and cross tensile strength in which the size, etc. of the weld samples was unified, and the tensile shear strength in changing the tensile direction and cross tensile strength in changing the peel direction for the vibration direction of the welding tip which applies ultrasonic vibration to weld samples have not been clarified. We performed ultrasonic welding using planar and linear vibrations with a change in weld time when the vibration direction of the tip of the welding tip applied to weld samples was changed. As a result, high tensile shear strength and cross tensile strength were obtained in a short time by ultrasonic welding using planar vibration. It was also clarified that there was almost no effect of the vibration direction of the welding tip on the tensile and peel directions.

In underwater acoustic communication, the Doppler shift can severely degrade demodulation performance. In addition, multipath signals can have the Doppler shifts that are different from that of a direct signal. Although conventional signal processing in underwater acoustic communication can deal with multipath signals with the Doppler shifts equal to that of the direct signal, they cannot sufficiently deal with multipath signals with different Doppler shifts. In this paper, we provide a mathematical description of how multipath signals with the different Doppler shifts degrade demodulation performance. Moreover, signal processing, which suppresses the effects of such multipath signals, has been proposed. In addition, to confirm the improvement due to the proposed processing, simulations of communication between a small surface vessel and an underwater vehicle were carried out in this study. The results show that the proposed processing yields a demodulation performance better than that of conventional processing. Furthermore, we investigated how the proposed processing improved the performance under some motional conditions. Finally, through simulations at various symbol rates, the motional and signal conditions under which the proposed processing can improve the performance efficiently are discussed.

The aim of this fundamental study is to investigate acoustic changes and perceptual impressions by singing and vocal training in 11 dysarthric Japanese patients. We also examined to improve their speech intelligibility through this training. Dysarthria is a speech disorder caused by diseases such as stroke, intractable neurological disease, and sequelae of head trauma. In terms of vocal evaluations, pre-test, mid-test, post-test, and follow-up test were performed quarterly to investigate a correlation between the five acoustic features of the singing voice (i.e. normalized frequency (pitch) score (NFS), normalized rhythm (duration) score (NRS), normalized intensity (power) score (NIS), frequency deviation (FD) and the intensity deviation (ID)) and speech intelligibility. These factors were evaluated based on the perceptual impression of a group of music major students (MS) and a group of non-music major students (NMS). The objective acoustic features revealed that the order of NRS, NIS, NFS, FD, and ID was higher in correlation with human subjective evaluation. The pre-test results of speech intelligibility indicated a greater improvement in the low intelligibility group than in the high intelligibility group. Furthermore, no difference was found in how perceptual impressions were evaluated between the MS and NMS groups.

The development of windows with high sound insulation performance is essential for preventing the infiltration of traffic noise and the leakage of room noise. A numerical prediction is an effective means of reducing sound insulation testing and development costs to develop a quietness window. As a numerical prediction method for the sound reduction index, the finite element method (FEM) is useful in dealing with structure-acoustic problems. This study was conducted as a pilot study toward developing an accurate numerical model to predict the sound reduction index of a double window. We discussed the accuracy of an FEM model for predicting the diffuse incidence sound reduction index of double windows through a comparison with measured values for a simplified realistically scaled double window. The FE results were compared with measured ones for eight cases with and without a frame absorber. Results showed that the best match to measured values is obtained when using a frame absorber in all the perimeters inside the air cavity. Also, a better agreement is obtained at frequencies of 160–2,000 Hz in other cases. However, a marked discrepancy is found at frequencies above 2,000 Hz and below 160 Hz. Possible reasons for the discrepancies are also discussed.

Ultrasound technology that delivers a powerful sound wave with sharp directivity over a long distance in the air is required. As a sound source for this purpose, authors devised an ultrasonic sound source with a new shape in which the opening area is smaller than that of the complex reflective plate, and a reflective plate whose size is equivalent to the area of the vibrating plate was mounted to it. This reflective plate is composed of a planar reflective plate and a truncated cone-shaped reflective plate. In this study, first, the directional characteristics of a circular transverse vibrating plate-type aerial ultrasonic sound source with an integrated rigid wall structure were examined. Next, the planar reflective plate and truncated cone-shaped reflective plate were analyzed to refine the design. Furthermore, a sound source equipped with these reflective plates was fabricated, and various acoustic characteristics were investigated. As the results, when the input power of the sound source was 30 W, the sound pressure was 293 Pa at the distance of 2 m. This is a unidirectional sound wave with a very intense sound pressure.

The precedence effect (PE) of a direct sound (leading sound) and reflections (lagging sounds) and related phenomena in the median plane have been studied by some researchers. However, it is still not clear how the lagging sound arriving from the median plane affects the leading sound image, especially for short time delays that are relevant to early reflections in architectural spaces. This study investigates the conditions where the PE and the related phenomena such as the summing localization (SL) and split of the sound images (SSI) are observed in the median plane for short time delays below 10 ms. A psychophysical experiment with a mapping method is used to simultaneously observe the PE, SL, and SSI. The experimental results suggest that, for the time delay ms, a lagging sound from the median plane leads to a perception of single sound image but it has a more prominent influence on the perceived sound direction than that from the horizontal plane. Furthermore, for the range of time delay, the lagging sound from the median plane has a more prominent effect on the sound image direction as the time delay increases.

In this paper, a moving sound source and a receiver on an arbitrary trajectory are implemented in the two-dimensional finite difference-time domain (FDTD) method. Two methods are proposed to implement a moving point source and a receiver in the FDTD method in which physically valid analysis is possible including the Doppler effect. One is a direct method and the other is a convolution method. The formulations and numerical experiments are made for the two-dimensional sound field, and the accuracy of two proposed methods is compared. It is confirmed that both methods can be applied to the moving sound source and receiver including the Doppler effect, and that two methods have the almost same accuracy. It is found that the convolution method has an advantage that the source waveform and the moving speed can be freely changed at the time of convolution when either the source or receiver is stationary.