Volume 119, Issue 5, May 2006
Index of content:
- NONLINEAR ACOUSTICS 
119(2006); http://dx.doi.org/10.1121/1.2190161View Description Hide Description
The acoustic nonlinear parameter, , is an important piece of data whenever high intensity pressure fields are under consideration. In this work, an alternative method is proposed to measure this parameter. First, the method involves measuring the sound velocity and nonlinear waveform distortion of a finite amplitude plane wave propagating through a medium, Butanediol, whose density and attenuation law have been preliminarily determined. Measurements were performed in the nearfield of a piston where plane wave propagation regime exists. Impulse response of the hydrophone was determined and pressure waveforms were obtained by a convolution process. Then, the method involves modeling, in time domain and under experimental conditions, the theoretical nonlinear waveform distortion and fitting it to the experimental results by adjusting the parameter. Comparative measurements were performed using the technique of parametric interaction. The respective results for the two methods ( and ) are in a good agreement despite a smaller degree of accuracy for the proposed method.
119(2006); http://dx.doi.org/10.1121/1.2181087View Description Hide Description
An acoustical model of hurricane rainband formation is proposed. Self-excited acoustic resonance inside the spinning eye produces strong azimuthal and radial standing waves. These modes can cause large temperature fluctuations about the dew point which are believed to be responsible for observed dry/wet bands in the outer storm disk. Distortion of standing wavefronts into spirals occurs in the transition layer region between approximately geostrophic flow inside the eyewall and irrotational flow outside. Tonal emissions from hurricane eyes should be detectable at great distances and are likely to be in a range below .