re history question in article snap paj uk co gec mrc paul johnson writes this is vague so i am posting it in case anyone else knows more i recall reading of a phonograph which used mechanical amplification compressed air was squirted out of a valve which was controlled by the pickup the result was noisy and distinctly lo fi but much louder nasa and related agencies apparently used this same principles to create the loudest reported reproduced sound they used an analog electrically controlled valve to control the flow of air across a horn throat if i remember correctly it was called a modulated air blast transducer there were reports of the thing being able to produce db hz mile distance communicate directly with fighter pilots ft etc regards gordon waters clyde gordon bme georgia institute of technology atlanta ga out of the mountain of despair we can hew the stone of hope mlk jr uucp decvax hplabs ncar purdue rutgers gatech prism gt a internet gt a prism gatech edu
