We discuss the propagation of longitudinal and transverse waves in an unbounded transversely isotropic medium rotating about its axis of symmetry. A longitudinal wave can propagate only along the axis of symmetry. For a transverse wave, either the wave normal or the polarization vector must be parallel to the axis of rotation, in general. Transverse waves also exist for special orientations of the wave normal.

View full abstract

In previous work, the authors examined the tendency of changes in the Speech Transmission Index (STI) using several modeled sound fields. The results showed that energy concentration due to strong reflections at any delay time, short or long, increases the STI. This means that the STI evaluates only the degree of energy concentration or dispersion in the time domain regardless of the delay time. As such, the STI fundamentally contradicts the generally accepted concept that early reflection is important in speech intelligibility. However, it has not yet been clarified as to whether such a property of the STI corresponds to intelligibility or merely reveals a defect in the STI. To examine the validity of the STI, speech intelligibility tests were conducted using sound fields with different energy concentration points. The results show that energy concentration at shorter delay times increases intelligibility, thus reconfirming the concept of importance of early energy, and indicates clear disagreement with the STI. The STI cannot be considered to correspond to intelligibility because it does not distinguish useful early energy from non-early energy, which does not contribute to intelligibility.

View full abstract

The frequency dependence of the acoustic radiation pressure on a solid elastic sphere placed freely in an incident plane progressive sound field in water has been investigated. In particular, the behavior of the acoustic radiation pressure at resonance frequencies of the elastic vibration of the sphere has been studied theoretically by taking into account the three components of the radiation pressure, namely, kinetic energy, potential energy, and tensor term. It has shown that the contribution of potential energy to radiation pressure is the largest and it has a positive value, that which of kinetic energy is rather small and has a negative value, and that which of tensor term is so small as to be negligible in the cases far from resonance frequencies. At resonance frequencies, potential energy falls off rapidly, while the softer the material are, the greater positive values kinetic energy and tensor term are increased up to, with a few exceptions. As a result, there takes place, in general, a series of maxima in the frequency characteristic curves of radiation pressure for relatively soft materials such as lead, and a series of minima for relatively hard materials such as iron at the resonance frequencies, because the increase in kinetic energy and in tensor term overcome the decrease in the potential energy for relatively soft materials. Materials of intermediate hardness such as brass have the frequency characteristic curves mixed by maxima and minima.

View full abstract

This paper numerically analyzes the sound pressure on an object in an ultrasonic cleaning vessel by considering the dissipation of cavitation bubbles. To clarify the effect of ultrasonic attenuation on the number of cavitation bubbles, the cavitation intensity on a brass object is measured experimentally by changing the quantity of water. Then, the analyzed sound pressure results are compared with the measured cavitation intensity results. The energy dissipation by the oscillation of bubbles is estimated by the irreversible process of heat and mass transfer. The calculation is carried out for the natural oscillation and forced oscillation of cavitation bubbles. It is found that the dissipation of thermal conduction results from the radial oscillation of bubbles by ultrasound. The sound pressure calculated by this dissipation agrees with the cavitation intensity profile estimated using experimental results from the erosion loss of aluminum foil. As the quantity of the water in the cleaning vessel is increased, the sound pressure becomes lower. This is because the amount of energy dissipation of the ultrasonic wave increases proportionally to the number of bubbles. However, when the standing wave causes resonance between the ultrasonic generator and the block, the effect of the sound pressure on the bottom of the block is not disturbed by the water volume.

View full abstract

In this article a new method for fundamental frequency estimation from the noisy spectrum of a speech signal is introduced. The fundamental frequency is one of the most essential characteristics for speech recognition, speech coding and so on. The proposed method uses the MUSIC algorithm, which is an eigen-based subspace decomposition method.

View full abstract

Two panels in Fig. 1 page 240 were misplaced. The proper positions of the two panels are following: The present upper panel which originally corresponds to “(b) Response rate in Z-score” should be lower and the present lower one which originally corresponds to “(a) Response rate” should be upper. Wrong: 
Right: 

View full abstract