Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site tektronix.UUCP Path: utzoo!linus!philabs!cmcl2!floyd!vax135!cornell!uw-beaver!tektronix!kimr From: kimr@tektronix.UUCP Newsgroups: net.audio Subject: How my ears are built Message-ID: <1211@tektronix.UUCP> Date: Thu, 7-Jul-83 00:13:56 EDT Article-I.D.: tektroni.1211 Posted: Thu Jul 7 00:13:56 1983 Date-Received: Fri, 1-Jul-83 22:30:27 EDT Organization: Tektronix, Beaverton OR Lines: 34 The ear, unlike some quasi-techno-freak audio equipment, was not designed to receive (produce) only sine waves. Current information is that the ear is sensitive to signal RISE times on the order of 10 microseconds. Instead of worrying about sine wave response of the ear, think about a 1000 hertz square wave with a 10 us rise time. It has sine wave harmonics exceeding 20 khz, and I'll bet that a well designed experiment will show audible differences if the rise time is limited to (say) 20 us. Interestingly enough, the chief difference between moving magnet and moving coil cartridges is their rise times - on the order of 10us for moving coil and 20us for moving magnet (16us for the Shure V15-V). A Time-Life book on music, circa 1965, shows the waveform of a kettle drum attack. The caption indicates that the rise time of the waveform is 12us. For reproduction, I use KEF T-27 tweeters that are rated -3db at 37Khz. The Pyramid T-1 ribbon tweeter is -3db at better than 80 Khz. Better yet, the Pyramid Met-7 ($295/pair) has a PUBLISHED rise time of 10us. I could continue: Quad ESL -3db @ 35 Khz... A competent stereo, (with competent source material) can produce an acoustic illusion which is 3-dimensional - realistic depth front-to-back, extending beyond the speakers to the sides, and most interestingly, top to bottom placement of instruments. You should be able to tell where the performers are in relation to the walls of the space they're performing in. And, if all goes right, you can convince yourself that you're attending a live performance, not listening to a mechanical reproduction. Until your system can reproduce this kind of illusion, it is far from the state of the art. And until the illusion is perfect, there is room for inprovement in the technology. AND UNTIL THAT'S TRUE, QUIT TELLING ME THAT IT'S BETTER THAN I CAN HEAR, BECAUSE IT'S NOT!! Kim Rochat ..!tektronix!kimr