1 REM Ins{nd av Kristoffer Eriksson <5357> 1988-11-04 20.26.08 (KERMIT) RISKS-LIST: RISKS-FORUM Digest Thursday 20 October 1988 Volume 7 : Issue 66 Date: 17 Oct 88 18:35:47 GMT From: miket@brspyr1.brs.com (Mike Trout) Subject: Nausea-inducing propeller (Re: RISKS DIGEST 7.64) In RISKS-FORUM Digest Volume 7 : Issue 64, Marshall Jose discusses how an unwanted 28 kHz spike at a Stevie Wonder tour was inducing irritability and impatience among artists, crew, and audience. Our illustrious moderator Peter also mentioned how the anapest beat of a particular rock tune could cause alarming physical effects on certain people. This brings to mind the story of the infamous XF-84H, an airplane whose tale appears every now and then in rec.aviation. You may remember the old F-84 Thunderstreak/flash/whatever; in those days jet engines left a great deal to be desired in both maximum power output and reliability. Accordingly, somebody got the bright idea of putting a super turboprop on the front of an F-84. Tests showed the plane (designated the XF-84H) to have lots of reliable power and acceleration, but there was an unexpected side effect nobody predicted: ground crews working with the XF-84H began suffering from uncontrollable nausea. The cause was traced to the plane's monstrous propeller blades, which of necessity were spinning at supersonic speeds and apparently setting up some physiologically harmful harmonics. The project was scrapped; the only XF-84H built is on display at some AFB in California, I believe. There seems to be little hard data in circulation about this project; it is mentioned briefly in various authoritative publications but the details are always sketchy. Some questions that come to mind: What kind of harmonics would induce nausea, rather than something like irritability as in the Stevie Wonder 28 kHz spike? Why was the pilot apparently not affected? Why is nausea NOT induced by other supersonically-spinning propellers (which occasionally crop up on various general aviation aircraft)? I'm sure that USAF and Republic Aviation reports on this incident exist somewhere; anybody know any more? BRS Information Technologies, 1200 Rt. 7, Latham, N.Y. 12110 (518) 783-1161 ------------------------------ Date: Mon, 17 Oct 88 08:59 EDT From: wolit@research.att.com Subject: Re: Ear-itating performance For one of his tours, Stevie Wonder contracted with Northwest Sound to build a set of PA speakers of extraordinary capability -- response nearly flat out to 45 kHz, etc. . . . . Finally, during one show, one of the sound guys was examining the audio spectrum analyzer screen, and mistakenly pushed the 20 kHz - 200 kHz range button instead of the 2 kHz - 20 kHz button. Imagine his alarm at the sight of a potent 28 kHz component, the product of all the synthesizers' DAC update clocks. . . . . If the DAC clock rate was 28 KHz, the synthesizers' Nyquist frequency (the highest frequency that could be reproduced) would have been only 14 KHz, which is pretty crummy and wouldn't have required a fancy sound system. Jan Wolitzky, AT&T Bell Labs, Murray Hill, NJ; 201 582-2998; mhuxd!wolit (Affiliation given for identification purposes only) ------------------------------ RISKS-LIST: RISKS-FORUM Digest Tuesday 25 October 1988 Volume 7 : Issue 67 Date: Thu, 20 Oct 88 16:45:34 -0700 From: chase@orc.olivetti.com (David Chase) Subject: Nausea-inducing frequencies ( Re: RISKS-7.66 ) Ask any competent neurologist and you should get a quick answer. Flashing lights at certain frequencies (I think 15Hz is one very important one) can induce nausea and/or epileptic seizures in some people. A neurologist told me of encountering three people in one day who had been zarked by the same failing flourescent bulb at a meat counter. Flashing lights are also a part of EEGs taken when epilepsy is suspected. As far as the props go, it could have been a visual flicker effect, or it could be that sounds can have a similar effect. May I suggest (to the curious among the audience) that you NOT try this experiment at home; epileptic seizures are not especially good for you, and the known occurrence of one tends to legally hinder your use of heavy equipment (like automobiles) for a period of time. David ------------------------------ RISKS-LIST: RISKS-FORUM Digest Monday 31 October 1988 Volume 7 : Issue 68 Return-Path: <@CSL.SRI.COM,@nyu.edu,@phri:eravin@dasys1.UUCP> Date: 24 Oct 88 15:10:19 GMT From: eravin@dasys1.UUCP (Ed Ravin) Subject: Ear-itation I've got my own story to tell about high frequency noises crawling out of computer related devices, and since I'm new to RISKS, my apologies if any or all of this has been discussed before. It all started back in college, when I went to a little office in the computing center. I walked into the room and immediately clapped my hands two my ears and shouted in aversion to the awful sound I was hearing. The two techs in the room, who worked in there most of the day, looked at me like I was crazy, because they didn't hear anything. It turned out to be the high-frequency whining from a Televideo terminal's flyback transformer. The two technicians never reported any ill effects from it. The few times I visited them again I had to stay outside of the office because of the direct pain I would experience walking in there when that terminal was turned on. After that I began noticing the sounds made by all the other CRT's in my life. They were high pitched and slightly irritating, but not painful. I had always, even before meeting computers, noticed the 15khz whine from a TV set, but it had never bothered me. My next experience was with a DEC VT-100. I visited a friend of mine who had an operating VT-100 in a little room in his house. Again, I heard a loud, high pitched whine that I felt as pressure in my ears and pain. He noticed nothing, but said that that particular VT-100 was stacked with option boards and might be overloading its power supply. I've worked with other VT-100 terminals and noticed noise, but not anywhere near as bad as that sample. And the best story of all is the AT&T Unix PC. All of the Unix PC's I ever worked with had a high-frequency noise problem to one extent or another, but the worst offenders were the ones with 40 meg disk drives installed. As soon as I turned on of them on, I would hear a high pitched noise that would slowly rise in pitch until it either went beyond my audible range or got lost in the fan noise. I thought nothing more of it until I realized that I was getting headaches, stomachaches, and feeling irritable without knowing why. I moved the machine to a closet and used it remotely. I polled everyone else at the office, as well as a few visitors from AT&T: almost noone could hear the noise from it, but anyone who had to work in the same room as the machine would eventually start complaining, even if the machine was parked in a noisy machine room. This wasn't limited to one sample, because we returned the machine and got it replaced two or three times, and none of them were acceptable to me. It wasn't just me, because we tried it out on a few other employees, who complained of irritation, stomachaches and toothaches after being in the same room as the Unix PC after a few days. This noise was definitely associated with the hard drive (as opposed to the flyback transformer who is the usual culprit), and was in the 20khz or above range, since I couldn't directly hear it, but felt it as a slight pressure in my ears. I have walked up to airline reservation counters, car rental counters, and other service desks where the ubiquitous VDT is part of the worker's routine, where the worker must sit in front of the terminal all day, and blanched from the whine coming out of the back of the CRT. As a white collar employeee in a technical office, with a moderately eloquent speaking ability, I was able to explain to my managers why I couldn't use certain equipment and they understood and assisted me. The information industry service worker has no such options: you can work on the machine or you can get another job. Managers over 40 probably can't even hear at 15khz, and will not understand what you're talking about. There have been numerous studies of "cluster miscarriages", where a high proportion of pregnant women using a particular brand of VDT all experience miscarriages, but most studies of VDT hazards seem to focus on low level radiation and ignore sound emissions completely. There are no OSHA or NIOSH standards on high-frequency sound or ultrasound emmissions from devices in the workplace: the engineers who build these things are used to listening to 15 or 20 khz whines all day long and no longer notice such things. Maybe my problem is that I never listened to loud rock music and my hearing above 15khz is mostly intact. But even when you can't hear it, that noise can still bother you, as witnessed by the Stevie Wonder experience (if not my own). And I wouldn't be surprised if it has a factor in miscarriages: one of the things ultrasound can do is heat up the tissue under your skin, which is related to the hospital uses of ultrasound devices. The scary thing is that so many people just dismiss this problem because they "can't hear it". Ed Ravin | cucard!dasys1!eravin (BigElectricCatPublicUNIX)| eravin@dasys1.UUCP Reader bears responsibility for all opinions expressed in this article.