abstract background: given the fact of irrecoverable consequences of noise in industrial societies and the environment, acoustic filter (silencer) is an instrument which obstacles the transmission of sound waves. a sort of this silencer is helmholtz resonator (branch amplifier) which comes to sound appropriate for low and below 200 hz frequencies in fan and channel noise. the purpose of this ar...

The control of the spatial distribution of noise and sound has been widely investigated for achieving passive and active noise control. By extending the concepts of active noise control and zones of quiet, one can sketch sound, i.e., synthesize sound fields of various shapes using loudspeaker arrays to achieve the desired sound quality in a finite zone of interest. Sound sketching involves repr...

childhood from a purely clinical standpoint. We think the author has admirably succeeded in his aim and object. The fact that the work is written in a more or less colloquial style adds to, rather than detracts from, its interest. The book abounds in sound practical teaching, and the parts dealing with treatment, which is laid special stress on, are not the least valuable portions of the work. ...

When beamforming is applied for acoustic source mapping, the sound pressure contributions of any sound sources are most often mapped to a planar or a surface map. However, some practical applications would benefit from a three-dimensional mapping, where the map consists of a three-dimensional grid. It is shown that the extension of microphone array beamforming techniques to three-dimensional ma...

Abstract Sound generating human activities so-called “anthropogenic sound” have increased ambient sound levels considerably in aquatic habitats that are markedly diverse in time and space. Sound generating human activities is now recognized as a potential driver of environmental changes in marine habitats. Iran has 750 km coastline along the Caspian Sea located in the north and around 2250 km ...

A questionnaire was mailed to 182 attendees of four practical workshops on fibreoptic endoscopy. After the workshops, 35% of the attendees were able to introduce fibreoptic intubation into their clinical practice or improve their success rate. This suggests that a new psychomotor skill can be disseminated effectively to clinicians by a practical workshop that utilizes inanimate models, and is b...

Wave field synthesis (WFS) is a prevalent approach to multiple-loudspeaker sound reproduction for an extended listening area. Although powerful as a theoretical concept, its deployment is hampered by practical limitations due to diffraction, aliasing, and the effects of the listening room. Reconstructing the desired sound field in the listening area, accounting for the medium propagation charac...