A coherent Alfv6n wave propagating along the equilibrium magnetic field is unstable against decay into an Alfv6n wave traveling in the opposite direction and a sound wave [Sagdeer and Galeev, 1969]. The stability of incoherent Alfv6n waves against his mode decay is considered, assuming that the sound waves are damped. The criterion for stabilizing waves with power spectral density In o• k -N is...

The propagation of sound waves at infrasonic frequencies (oscillation periods 1.0 1000 seconds) in the atmosphere is being studied by a network of seven stations separated geographically by distances of the order of thousands of kilometers. One of the typical stations, in Washington, D. C., has an array of five microphones separated by distances of about 7 kilometers. Each microphone is at grou...

Travelling waves are the physical basis of frequency discrimination in many vertebrate and invertebrate taxa, including mammals, birds, and some insects. In bushcrickets (Tettigoniidae), the crista acustica is the hearing organ that has been shown to use sound-induced travelling waves. Up to now, data on mechanical characteristics of sound-induced travelling waves were only available along the ...

This paper extends the theory of the diffraction of sound on 1D corrugated surfaces to 2D corrugated surfaces. Such surfaces, that are egg crate shaped, diffract incoming sound into all polar directions, which is fundamentally different from 1D corrugated surfaces. A theoretical justification is given for extending the classical grating equation to the case of incident inhomogeneous waves, for ...

Place based frequency discrimination (tonotopy) is a fundamental property of the coiled mammalian cochlea. Sound vibrations mechanically conducted to the hearing organ manifest themselves into slow moving waves that travel along the length of the organ, also referred to as traveling waves. These traveling waves form the basis of the tonotopic frequency representation in the inner ear of mammals...

23 S ound in multimedia, movies, games, virtual reality, and human–computer interfaces is a growing field that encompasses the disciplines of analog and digital signal processing, physics, speech, music, perception, and computer systems architecture. This overview of sound production and modeling techniques surveys the state of the art in sound technology. Sound has become a critical component ...

A study of 400 Hz sound focusing and ducting effects in a packet of curved nonlinear internal waves in shallow water is presented. Sound propagation roughly along the crests of the waves is simulated with a three-dimensional parabolic equation computational code, and the results are compared to measured propagation along fixed 3 and 6 km source/receiver paths. The measurements were made on the ...

We investigate the behavior of upward running sound waves in the lower photosphere by means of a 2-hour time series of FPI-filtergrams and a corresponding series of whitelight images. From the FPI-filtergrams we obtain velocities in two heights in the solar photosphere. Using specific filters in the kh-ν-space, we extract running sound waves from the velocity time series and the granulation fro...