logos labs holosound
ultrasound transducers
http://www.logosfoundation.org/
http://www.logosfoundation.org/laboratory.html :
"Godfried-Willem Raes for his research projects
in the realms of alternative musical instruments
based on remote movement sensing and automation."
 * ultrasonic condenser microphones for 80-240kHz

Quadrada (2003)
http://www.logosfoundation.org/ii/quadrada.html
microwave radar installation for capturing info
on human body movement
 
http://www.logosfoundation.org/ii/gesture-instrument.html

http://www.logosfoundation.org/ii/picradar.html

Ultrasound:
 "Usual freq for air transducers are 28kHz - 200kHz.
  Higher freq are only for use in fluids: medical instruments.
  Most common is 40kHz, mostly for intruder alarms."
 "Piesoelectric in self oscillating mode has way too much freq drift."
 emitter: 40kHz, 0.5W output
 reciever: 

Microwave:
 Siemens KMY24 or HFMD24
 2.45GHz
 (RFID on performers clothes?)


http://www.best-microcontroller-projects.com/pic-sonar.html
 pulsed 3m range echo ranger
 Ultrasonic RX microphone                 "M2"
 Ultrasonic TX ultrasonic piezo sounder   "WD1"

http://miyaweba.elec.ryukoku.ac.jp/miyashita/papers/jjap98m.pdf
 Reconstruction of Wide-Bandwith scattering responses
 from Narrow-bandwidth ultrasound echo in air

http://www.parteqinnovations.com/iandi-micromachined.html

http://www.robot-electronics.co.uk/shop/Ultrasonic_Rangers1999.htm
(look at parts, not circuit)

400ST/R160
SRF04

http://ultrasonic-transducers.globalspec.com/Industrial-Directory/ultrasonic_ceramic_transducers

http://www.robot-electronics.co.uk/datasheets/t400s16.pdf
 400ST160 transmitter
 400SR160 receiver
 used for echo location

http://www.steminc.com/piezo/airtrans.asp