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 the...

the use of acoustic waves in researches related to sea water is of most importance among scientistsrecently. since these waves are the only waves, transmitted in water with lowest attenuation and high speed, they canbe used in many scientific fields. the main goal of this research is to better understand the physics and mechanismsof sound-seabed interaction, including acoustic penetration, prop...

We formally derive the simplest possible periodic wave structure consistent with time-periodic sound wave propagation in the 3 × 3 nonlinear compressible Euler equations. The construction is based on identifying the simplest periodic pattern with the property that compression is counter-balanced by rarefaction along every characteristic. Our derivation leads to an explicit description of shock-...

Existence of outflow intrusion introduces small-scale turbulence that perturbs the vertically stratified character of the sound velocity and causes spatial and temporal fluctuations of the sound propagation. In this experimental study, we have investigated acoustic wave propagation with frequency of 50 kHz in a pre-stratified environment with intrusion of a turbulent plume while the si...

Sound-field imaging, the visualization of spatial and temporal distribution of acoustical properties such as sound pressure, is useful for understanding acoustical phenomena. This study investigated the use of parallel phase-shifting interferometry (PPSI) with a high-speed polarization camera for imaging a sound field, particularly high-speed imaging of propagating sound waves. The experimental...

The propagation of sound in a density-stratified fluid is examined in an experiment with a tank of salty water whose density increases continuously from the fluid surface to the tank bottom. Measurements of the height dependence of the fluid density are used to calculate the height dependence of the fluid salinity and sound speed. The height-dependent sound speed is then used to calculate the r...