Outstanding Instruments:

RCA Electronic Music Synthesizer, Harry Olson and Hebert Belar, USA, 1955
a brief history with sound excerpts on:
http://uv201.com/Misc_Pages/rca_synthesizer.htm

ANS Photo-optic Synthesizer, Alexander Nikolayevich Scriabin, USSR, 1958
http://theremin.ru/archive/ans.htm
order a related publication at the MIT Press: ISSN: 0024094X

Con Brio ADS 200, USA, 1971
some information here: http://www.synthmuseum.com/conbrio/conads20001.html

not instruments but still on the tip:

Acoustic mirrors, english south coast, 1920s

http://www.doramusic.com/soundmirrors.htm
http://www.ajg41.clara.co.uk/mirrors/dungeness.html
http://www.castlekas.freeserve.co.uk/sound_mirrors.htm
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2001/01/29/namp29.xml

more acoustic radars...

http://www.dself.dsl.pipex.com/MUSEUM/COMMS/ear/ear.htm

On speech synthesis:

Key figures:

Werner Meyer Eppler, 1913-1960,

Homer Dudley,

researcher at bell laboratories, inventor of the vocoder in 1939
http://www.bell-labs.com/org/1133/Heritage/Vocoder/. .
http://www.obsolete.com/120_years/machines/vocoder/

A Short Introduction to Text-to-Speech Synthesis

http://tcts.fpms.ac.be/synthesis/introtts_old.html

text to speech interactive demo in us and uk english, spanish, german and french
http://www.research.att.com/projects/tts/demo.html

The Smithsonian Speech Synthesis History Project,
a Division of Information Technology and Society of The NATIONAL MUSEUM OF AMERICAN HISTORY
http://www.mindspring.com/~ssshp/ssshp_cd/ss_btl1.htm

A brief introduction to voice synthesis (in german)
http://www.msc175.de/projekte/vocoder/sprachsynthese.htm

Unsorted related:

understand Audio Synthesis via Vacuum Tubes
http://www.cgs.synth.net/tube/index.html

the Acid Varsity

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