surrounding space. A sound installation is usually site-specific, but sometimes it can be readapted to other spaces. It can be made either in closed or open spaces, and context is fundamental in determining how a sound installation will be aesthetically perceived. The difference between a regular art installation and a sound installation is that the latter contains a time element, which gives the visiting public the option to stay longer to explore the development of the sound over time. This temporal factor also gives the audience an incentive to explore the space more thoroughly and investigate the disposition of the different sounds in space. Sound installations sometimes use interactive art technology (computers, sensors, mechanical and kinetic devices, etc.), but they can also simply use sound sources placed at different points in space (such as speakers), or acoustic instrument materials such as piano strings played by a performer or by the public (see Paul Panhuysen). In the context of museums, this combination of interactive technology and multi-channel speaker distribution is sometimes referred to as sound scenography. Sound structure in sound installations The simplest sound form is a repeating sound loop. This is mostly used in Ambient music-like art, and in this case the sound is not the determinant factor of the art work. The most used sound structure is the open form, since the public can decide to experience a sound installation for just a few minutes or for a longer period of time. This obliges the artist to construct a sound organization that is capable of working well in both cases. There is also the possibility to have a linear sound structure, where sound develops in the same way as in a musical composition. Sound sculpture Sound sculpture is an intermedia and time-based art form in which sculpture or any kind of art object produces sound, or the reverse (in the sense that sound is manipulated in such a way as to create a sculptural as opposed to temporal form or mass). Most often sound sculpture artists were primarily either visual artists or composers, not having started out directly making sound sculpture. Cymatics and kinetic art have influenced sound sculpture. Sound sculpture is sometimes site-specific. Sound Artist and Professor of Art at Claremont Graduate University Michael Brewster described his own works as "Acoustic Sculptures" as early as 1970. Grayson described sound sculpture in 1975 as "the integration of visual form