Sound generation

The sound generation mechanism involves the transmission of acoustic energy in space. Therefore, the power of a sound source is the energy emitted in time units and is measured in W. 

Acoustic Emission Acoustic emission (AE) describes the technique in which sound generated by a metal under stress can be detected The... 

Previous data have concerned rmconfined flame configurations driven by velocity perturbations. These cases are less dependent on the geometry because sound generation is not modified by reflection from boundaries. It is also easier to examine rmconfined flames with optical techniques. However, in many applications, combustion takes place in confined environments and sound radiation takes place from the combustor inlet or exhaust sections. The presence of bormdaries has two main effects ... 

R. Clavin and E.D. Siggia. Turbulent premixed flames and sound generation. Combust. Sci. Technol., 78 147-155,1991. 

In the study by Henglein and Gutierrez, a commercial 20-kHz sound generator (KLN System 582 horn diameter, 14 mm) was also used. The solution (20 mL) was irradiated in a beaker (30-mm i.d.), with the distance between the horn and the bottom of the vessel being 24 mm. 

Oyama, Y., Okada, M., Sawahata, Y., and Inoue, I., "Design Note on Siren -Type Sound Generator", Journal of the Scientific Research Institute, Vol, 50, No. 1419, pp. 374-42, 1956. 

There is another method in which one listens for noise, but this time the meaning is more conventional. The technique listens to the sound generated by the breakdown of materials. Absence of a commercially available apparatus limits its application at this time. 

Operating at gas flow rates appropriate for GC separations, frequencies ranging from 30-50 kHz (supersonic frequencies) were observed. The actual sensor contained two sound generators, one operating with pure carrier gas and the other with the eluent from the column. The two frequencies were allowed to beat together, the beat frequency being directly related to the frequency difference between the two whistles and consequently the density difference between the contents of the... 

In addition to producing sound, sound cards have another capability that is often overlooked. The Musical Instrument Digital Interface (MIDI—usually pronounced middy ) technology incorporated into most sound cards allows PCs to talk with (and in some cases, control) musical devices. With the addition of a special adapter cable that plugs into the game port on most sound cards, a PC can use external sound modules to produce sounds. MIDI technologies are used by most electronic keyboard players and professional musicians. However, you don t need to have an electronic keyboard or external sound module to play MIDI sounds. Most sound cards include a set of ICs that incorporate some of the sound-generating circuitry found in most electronic keyboards. 

The Taylor sound meter measures the sound generated by a textile when it is drawn over glass pins. 

Colonius, T., S.K. Lele, and P. Moin. 1993. Boundary conditions for direct computation of aerodynamic sound generation. AIAA J 31(9) 1574-82. 

Zhang, Z., L. Mongeau, and S.H. Frankel. 2002. Experimental verification of the quasi-steady assumption for aerodynamic sound generation by pulsating jets in tubes. J. Acoustical Society America 112(4) 1652-63. 

The most compelling aspects of the techniques, concepts, and research presented in this book are that they are essentially infinitely open ended. There will always be interesting new sounds, new physical discoveries, and new sound synthesis techniques developed which can bring expression and realism to sound effects synthesis. Oiu physical understanding is not yet complete in the areas of friction, nonlinear fluid dynamics, and countless other phenomena which cannot be easily observed or measured. Even if this knowledge were complete, systematic studies of the sound generation and radiation of such systems have not yet been carried out. 

It should be noted that audible sound (generated by cheap loudspeakers) can be used for related separation techniques, even on large scales (pilot plant). A reduction in particle emissions from coal combustion fumes has been achieved using an array of stepped-plate piezoelectric transducers, which produce a homogeneous distribution of high-intensity waves (145-165 dB), located along the waU of the chamber at that high-temperature environment [135]. 

A favourite application is the substitution of materials for boxes in sound generation because the material is optimal for suppressing unwanted resonances and damping oscillations. 

---