Finite-difference, time-domain (FDTD) calculations are typically performed with partial differential equations that are first order in time. Equation sets appropriate for FDTD calculations in a moving inhomogeneous medium (with an emphasis on the atmosphere) are derived and discussed in this paper. Two candidate equation sets, both derived from linearized equations of fluid dynamics, are propos...

The Microflown is an acoustic sensor measuring particle velocity instead of sound pressure, which is usually measured by conventional microphones. Since its recent invention it is mostly used for measurement purposes (1D and 3D-sound intensity measurement and acoustic impedance). The Microflown is also used for measuring DC-flows, that can be considered as particle velocity with a frequency of ...

The density (ρ) and ultrasonic velocity (U) for ternary mixture of dimethyl acetamide, isobutyl methyl ketone and diethyl ether at different frequencies (2MHZ, 4MHz, 6MHZ, 8MHZ) have been measured at 308K. These data have been used to compute adiabatic compressibility (Ks), intermolecular free length (Lf), acoustic Impedance (Z), molar volume (Vm), molar sound velocity(R), molar compressibility...

It is accepted that noise pollution has a major impact on health, such as physical, physiological, psychological and performance related effects, all over the world. This study aims to evaluate noise pollution in four urban parks located in Sanandaj City, Iran and to zone it in GIS environment. Sound pressure level (SPL) and maximum sound level (Lmax) were measured at 45 points (each point was ...

the current study presents the results of the aerodynamic noise prediction of the flow field around a naca 0012 airfoil at a chord-based reynolds number of 100,000 and at 8.4 degree angle of attack. an incompressible large eddy simulation (les) turbulence model is applied to obtain the instantaneous turbulent flow field. the noise prediction is performed by the ffowcs williams and hawkings (fw-...

This paper presents an overview of the timbre perception research. Timbre is found to be multidimensional, having a spectral envelope axis, mainly defined by the brightness of the sound, a temporal envelope, defined by the attack time, the decay slope, etc. and spectral irregularities. Furthermore, a model of quasi-harmonic sounds, the hybrid model, a timbre inspired signal model, is used to as...

Measurements of middle ear (ME) acoustic power flow and related measures (e.g., reflectance, absorbance, impedance, resistance, and reactance) have several important advantages over other measures of acoustic impedance, such as the clinical “gold standard” measure, tympanometry. In addition to its wide bandwidth and ease of use, the absorbance curve, on a dB scale, has a shape that is similar t...