In conventional near-field acoustic holography (NAH) it is not possible to distinguish between sound from the two sides of the array, thus, it is a requirement that all the sources are confined to only one side and radiate into a free field. When this requirement cannot be fulfilled, sound field separation techniques make it possible to distinguish between outgoing and incoming waves from the t...

This paper investigates the effect of various modifications to an acoustic steel string guitar on lowfrequency dynamics and sound pressure level. Modifications include string tension, sound-hole area and depth, bridge pin mass, top plate mass, stiffness and damping. Frequency response measurements are provided for all modifications considered. A lumped parameter model is found to capture the ch...

The sound radiation characteristics of a semi-hermetic twin-screw compressor were studied while operating under controlled laboratory conditions at the Ray W. Herrick Laboratories of Purdue University. A fully-condensing load stand was designed to allow the 70 ton chiller system to be operated at the three standard loading capacities of the compressor. The load stand was operator controlled and...

This paper presents noise problems associated with the use of air-turbine drills in dental practice. Two hundred and fifty dentists (male and female) were randomly selected from the faculty of dentistry as well as the dentists who worked private in Tehran. The results indicated that the mean value of sound pressure level produced by the high-speed drills was 69.1 db. Most of the energy from...

Stress has become an increasingly important occupational health matter in Japan. We found that noise exposure, 6 kHz wave and its higher harmonics at the sound pressure level of 112 dB, induced typical audiogenic seizures in the MRL/l mouse strain. The seizures are often fatal. Wild running preludes to seizures. Inhibition of wild running by restricting animal's activities successfully prevente...

INTRODUCTION The use of Personal Digital Audio Players can cause hearing injuries, as the sound is generated directly in the ear canal. It is believed that different types of headphones can cause different amplifications, since they cause changes in the volume and resonance of the ear canal according to their depth. OBJECTIVE This study aimed to determine the sound pressure to which young ind...

The sound pressure correlates of the second heart sound were studied in 22 patients during diagnostic cardiac catheterization. Simultaneous right ventricular and pulmonary artery pressures were recorded with equisensitive catheter-tip micromanometers together with the external phonocardiogram and ECG. In 12 patients having normal pulmonary vascular resistance (group 1), pulmonic closure sound w...

in the course of this study, empirical models were developed for the pressure-density relationship in a large cubic baler for baling alfalfa and barley straw. least squares regression analysis was employed to develop the empirical model and estimate the model coefficients by minimizing the summation of the squared differences between data resulting from the developed empirical model and the cor...

several relationships to assess at-rest pressure coefficient in retaining walls, have been developed by different researchers. these suggested relationships are generally a function of mechanical soil parameters such as internal friction angel, poison ratio and over-consolidation ratio. in integral bridges, however, this coefficient is also a function of many other parameters other than soil ch...

abstract: compaction under tractors tires is of special concern because the weight of these machines has increased dramatically in the last years. these machines and others associated with crop cultural practices weight enough to significantly compact the soil, especially if the soil is soft with high moisture content during tilling, planting, or harvesting. the stress distribution and the size...