We discuss the methodology of the validation of a higher order discontinuous Galerkin scheme for acoustic computations. That includes an accurate definition of the exact solution in the problem as well as careful study of convergence properties of a DG scheme for a chosen acoustic problem. The efficiency of a higher order scheme will be confirmed for computations on coarse meshes.

Cochlear implants stimulate the auditory nerve with amplitude-modulated (AM) electric pulse trains. Pulse rates >2,000 pulses per second (pps) have been hypothesized to enhance transmission of temporal information. Recent studies, however, have shown that higher pulse rates impair phase locking to sinusoidal AM in the auditory cortex and impair perceptual modulation detection. Here, we investig...

This paper discusses two issues of the quality improvement of F0 modified speech based upon PSOLA analysissynthesis. Previous studies[1][2] pointed out that the location of a window of PSOLA influences the quality of synthesized speech and one of them claimed that the center of a window should be located at a pitch pulse in source waveforms. However, pitch pulse detection sometimes fails due to...

This paper discusses the measurement of the acoustical properties of tubular systems using pulse reflectometry. The technique involves the injection of a sound pulse into the object under investigation and the recording of the resultant reflections. Analysis of the reflections gives information about the bore profile and input impedance of the object. The effect of small leaks on both of these ...

Acoustic techniques are used to monitor the temperature of silicon wafers in rapid thermal processing environments from room temperature to 1000" C with f 5 " C accuracy. Acoustic transducers are mounted at the bases of the quartz pins that support the silicon wafer during processing. An electrical pulse applied across the transducer generates an extensional mode acoustic wave which is guided b...

Phase aberration due to tissues with inhomogeneous acoustic speeds is a major source for image degradation in medical ultrasound. In most phased array pulse-echo ultrasound systems, the delay used to steer and focus the beams are calculated assuming constant speed. In practice, however, the acoustic speed varies for different types of tissue. In this paper, we present a method to estimate the p...

The acoustic boundary conditions at the site of laser irradiation affects the onset of cavitation when stress-confined laser pulses are used. This study reports the thresholds for cavitation when the laser pulse length exceeds the stress confinement time by a factor of eight. The cavitation threshold was defined as the loss of an acoustic signal from the collapse of the cavitation bubble in roo...

Coalescing bubbles are known to produce a pulse of sound at the moment of coalescence, but the mechanism driving the sound production is uncertain. A candidate mechanism for the acoustic forcing is the rapid increase in the bubble volume, as the neck of air joining the two parent bubbles expands. A simple model is presented here for the volume forcing caused by the coalescence dynamics, and its...