Talk:Parabolic loudspeaker

A fact from Parabolic loudspeaker appeared on Wikipedia's Main Page in the Did you know column on 31 August 2009 (check views). The text of the entry was as follows:

Did you know... that one of the public address applications of parabolic loudspeakers is to project sound waves in a 10° cone pattern 300 feet (90 m) away?

A record of the entry may be seen at Wikipedia:Recent additions/2009/August.

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Holophones

1. The very first utilization of a paraboloid mirror dates back to the 2nd century AD. Author Lucian wrote that during the Siege of Syracuse (c. 214–212 BC), Archimedes destroyed enemy ships with fire. Centuries later, Anthemius of Tralles mentions burning-glasses as Archimedes' weapon. The device, sometimes called the "Archimedes heat ray", was used to focus sunlight onto approaching ships, causing them to catch fire. It was also known the opposite utilization: the rays coming from the focus are reflected in the direction parallel to the paraboloid axis.

2. The Holophones have been conceived in 1999 as art sound installation for sound spatialisation in the work Gran Cassa by composer Michelangelo Lupone (premiered in 2000) and then used for a special spatialisation of computer music works.

3. The word Holophones (plural!) means a cluster of sound projectors dynamically controlled by a computer. Each sound projector is composed by not just a parabolic loudspeaker but also - a dynamic phase, amplitude and frequency modulator - a dynamic filters array both specifically designed for the music work performed.

We would really appreciate if you could please restore the previous article and photos (regarding art sound installations using Holophones). We will post a link from the “Holophones” article to the “Parabolic loudspeaker” article. Please also remove the Holophones picture with caption “two parabolic loudspeakers” from your article; it represents just a single art sound installation using Holophones (ArteScienza 2006, Casina del Cardinal Bessarione, Rome, Italy). —Preceding unsigned comment added by CRMMusic (talk • contribs) 17:45, 18 August 2009 (UTC)[reply]

I moved the Holophones article to Parabolic loudspeaker because Holophones are not a noteworthy product by themselves. As a paragraph within parabolic loudspeaker, Holophones still need to prove their worth, but the article as a whole is not going to be deleted. Binksternet (talk) 18:21, 18 August 2009 (UTC)[reply]

calculation for reflector size is incorrect.

"... A parabolic reflector type of loudspeaker must have a diameter twice that of the lowest desired wavelength, so to obtain directional control of frequencies down to 20 Hz, the dish would have to be over 50 feet (15 m) wide. .." At 20hz sound waves at sea level and 20C are about 56 feet long. This would make a parabolic reflector capable of directing this frequency at least 112 feet across. BGriffin (talk) 02:35, 10 November 2018 (UTC)BGriffin[reply]