Recently, an acoustic waveguide sensor based on multiple mode conversion of surface acoustic waves at the solid-liquid interfaces has been introduced for the concentration measurement of binary and ternary mixtures, liquid level sensing, investigation of spatial inhomogenities or bubble detection. In this contribution the sound wave propagation within this acoustic waveguide sensor is visualize...

A sweep-frequency tympanometer has been developed to diagnose auditory ossicular lesions more precisely. This device measures acoustic middle ear features by changing the probe tone frequency continuously. The oscillator sweeps frequency of the probe tone from 200 to 2,500Hz 1.5 seconds. A microphone picks up the changes in the acoustic pressure and the phase in the external auditory meatus dur...

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...

An exploratory investigation of the feasibility of the Ionophone as a plasma research tool is described. A series of plots of acoustic output versus ambient pressure in helium and argon at several different acoustic and ultrasonic frequencies is presented, and suggestions are made for further work with the device. Table of

Nonlinear bubble dynamics are often viewed as the unfortunate consequence of having to use high acoustic pressure amplitudes when the void fraction in the near-surface oceanic bubble layer is great enough to cause severe attenuation (e.g. >50 dB/m). This is seen as unfortunate since existing models for acoustic propagation in bubbly liquids are based on linear bubble dynamics. However, the deve...

1. Abstract An efficient damping layout optimization method of structural-acoustic systems is proposed to minimize acoustic responses using a gradient-based optimization algorithm. To analyze vibro-acoustic systems, a hybrid model that uses finite elements for the structures and boundary element for the cavity is developed. The four-parameter fractional derivative model is used to represent the...

(Near-field Acoustic Holography, Audio Production, Guitar) In recording studios, the placement of microphones to record an acoustic guitar is very much subjected to trial and error and audio engineer preference. In order to make more informed microphone placement decisions, Near-field Acoustic Holography is used to study the sound pressures of the guitar. This technique involves solving the int...

The pressure dependences of the elastic constants and the sound velocities are calculated from first principles for 3C-SiC in the range 0–100 GPa. The sound velocities are found to decrease with increasing pressure for the lowest transverse acoustic ~TA! branches for the @110# and @111# sound wave propagation directions. For the @100# direction they first increase and then decrease at higher pr...