To realize the sound pressure unit directly, the method of sound pressure measurement based on acoustic particle velocity with LDA technique was described. In order to get a simple acoustic field, a travelling wave tube was designed. The sound pressure distribution obtained by microphone along the tube was measured. The result showed the acoustic field inside the tube could be considered as tra...

Acoustic wave is a physical field that includes both scale field and vector field. Acoustic Vector Sensor (or called Combined Acoustic Vector Transducer) can pick up the information contained in both pressure and velocity fields, so it makes possible to use much more information. This paper from several sides: principle, structure and possibilities of its future applications, briefly discusses ...

Photoacoustic tomography (PAT) is a novel tomographic imaging paradigm that combines the benefits of ultrasound imaging and optical tomography [8]. When a semitransparent sample is illuminated with a short pulse of electromagnetic energy, then parts of the optical energy become absorbed which in turn induces an acoustic pressure wave inside the sample (see Figure 1.1). The induced acoustic pres...

We report experimental results on the dynamics of a granular packing submitted to high-intensity focused ultrasound. Acoustic radiation pressure is shown to remotely induce local rearrangements within a pile as well as global motion around the focal spot in an initially jammed system. We demonstrate that this fluidization process is intermittent for a range of acoustic pressures and hysteretic ...

There are several sources for pressure oscillations in solid propellant rocket motors. Oscillatory flow field is one of them. Free shear layers in motor flow field cause vortex shedding. End edges of propellant grains and baffle edge in two-segmented motors are samples of such zones. These vortices move from their forming points and strike the field walls. The kinetic energy of vortices change ...

There are several sources for pressure oscillations in solid propellant rocket motors. Oscillatory flow field is one of them. Free shear layers in motor flow field cause vortex shedding. End edges of propellant grains and baffle edge in two-segmented motors are samples of such zones. These vortices move from their forming points and strike the field walls. The kinetic energy of vortices change ...

A design optimization procedure of a noise-vibrationharshness (NVH) problem of a complicated vehicle structure is presented by assuming the acoustic pressure does not affect the structural vibration. The steady-state dynamic behavior of the vehicle is calculated from the frequency response finite element analysis, while the sound pressure level within the acoustic cavity is calculated from the ...

This paper demonstrates that linear discriminant analysis using aerodynamic and acoustic features is effective in discriminating speakers with vocal-fold nodules from normal speakers. Simultaneous aerodynamic and acoustic measurements of vocal function were taken of 14 women with bilateral vocal-fold nodules and 12 women with normal voice production. Features were extracted from the glottal air...

A method for determining the spatially resolved acoustic field inside a water-filled microchannel is presented. The acoustic field, both amplitude and phase, is determined by measuring the change of the index of refraction of the water due to local pressure using stroboscopic illumination. Pressure distributions are measured for the fundamental pressure resonance in the water and two higher har...