-=> Quoting Bonnie Goodwin to Garth Robinson <=-
 BG> A device known as an "acoustical laser" was invented by them and
 BG> could have been a major factor if used in against a large group
 BG> of men on a battlefield. Basically it is two very high powered
 BG> ultrasonic drivers operated so that it would hetrodyne a beat
 BG> frequency in a subsonic range that would cause internal
        Have you heard about Carver's new hetrodyne speakers that they
are working on in cooperation with another company (forget the other
company's name)?  It uses two ultrasonic frequencies that hetrodyne
into the acoustical range.  Supposedly, the amplifiers created to run
these things will only need precision across 1/3 an octave in the
ultrasonic region (I forget what frequencies they're using exactly).
James Croft, Vice-President of Carver has been discussing the system
on rec.audio.high-end lately, although it's clear they still have a
ways to go.  However, these speakers supposedly will have next to no
room interaction and therefore will be able to present the original
soundstage accurately instead of combining with the room the speakers
are in as do all regular speakers.  They're also VERY tiny (since
they're essentially just ultrasonic tweeters).  Yet they'll reproduce
the entire audio spectrum including the bottom octaves usually
associated only with large subwoofers.  It almost sounds unreal, but
apparently they've had some real success with the technology after 10
years of research and so are now talking about it.
        If this pans out, it might just revolutionize the audio
industry.  Most of the major problems associated with conventional
loudspeakers will be eliminated such as room interaction, box
colorations, crossover distortion, etc.  As you mentioned, sound at
this level is more like a laser than a large wave, but apparently they
change this behavior by modifying where the hetrodyning occurs and by
the type of carrier they use.  I can't be specific since I don't
really understand everything he was talking about.  But it sounds
like a promising new technology for sound reproduction.  Perhaps the
largest coloration in the sound reproduction chain (speakers) will
soon be a thing of the past.... 
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