Since every material has it's own particular wave-field, it follows that the material of a pendulum can produce strong enough radiation to interfere with the wave-field under investigation. For this reason, keys or other metal objects are not recommended for use as pendulum weights. For their wave-fields are extremely strong, and erratic results occur when they are used..."[
/QUOTE]
https://en.wikipedia.org/wiki/Wave_field_synthesis
Wave field synthesis (WFS) is a
spatial audio rendering technique, characterized by creation of virtual
acoustic environments. It produces "artificial"
wave fronts synthesized by a large number of individually driven
speakers. Such wave fronts seem to originate from a virtual starting point, the
virtual source or
notional source. Contrary to traditional spatialization techniques such as
stereo or
surround sound, the localization of virtual sources in WFS does not depend on or change with the listener's position.
Edward Tufte forum: Wavefields: intense animated data graphics
"Wavefields" are data graphics that draw on and completely fill the
entire
display surface, using every pixel on the data plane to show high-resolution,
complex, multiple, animated statistical data-flows. Wavefields extend my work on
sparklines.
