Acoustics
Echoes
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To obtain good texture it is
necessary to avoid any particularly large single echoes; the
direct sound followed by a large echo gives the illusion of
a performance inside a large can. One way to obtain a very large echo
is to make the stage in the shape of a parabola with highly reflective
walls, with the performers at the focus. The direct sound will then
be followed by a large echo obtained when the sound is reflected
off the rear of the stage reaches the audience as plane wave.
Another important echo effect is the flutter echo, which can be obtained when two side walls of the auditorium are parallel to each other and made of highly reflective materials. In this case the sound reflects back and forth between the two sides, creating a rapid sequence of echoes. These reflections can even lead to destructive interferences between the various reflected waves. |
Ch. Elster