KARL!!!???
(Emailed to a friend of mine by Connie Sabon)
Gentlemen;
Thank you for giving us the opportunity to respond to Mr. Fish and Mr.
Mehr. You have our permission to post our response wherever Messrs. Fish and Mehr have posted their "findings".
Best regards,
American Technology Corporation
At your request, this is a response to the 2/6/97 message to SunAge and to Carl A. Mehr as well as his guru Russell Fish III.
To start with, Fish states that he "had a study done about the ATCO Speakerless sound reproduction," and then proceeds to disagree with just about all of ATC's claims regarding the technology. Just how one goes about undertaking any kind of meaningful study of a technology of which one has so many misconceptions is hard to understand.
In spite of the above, this rebuttal is given in a spirit of goodwill and in the hopes that an enlightened discussion of Mehr's generally negative comments might serve some useful purpose. A brief example in advance of the following comments is deemed noteworthy-- Henry Ford and Thomas Edison were both geniuses in their own right. Each had a brilliance that cannot be questioned (neither was a college graduate). On one occasion, Edison is quoted as telling his friend Henry that if he ever made a car that traveled at sustained speeds of more than 15 miles per hour he would surely cause great destruction from hurricanes. A good point to remember; even the great ones are often mistaken.
Fish/Mehr comment on some of ATC's public claims by dividing them into five groups. The topic groups are followed by several other observations. In this response, specific comments made by either Fish or Mehr are presented in "quotes."
Any of their statements and/or observations that are deemed incorrect will be noted here. They will be discussed in the order in which they appeared.
Group 1. Fish states that ATC claims "It's new."
According to Fish: "It's not."
Response: He's right on the first count. ATC claims that what is has achieved is a first, and has filed numerous patent applications on that accomplishment. The fact that others have known of the underlying effect and tried to make it work (but failed) means nothing. Virtually all new technologies take advantage of known principles. One might reason that since birds fly, the invention of the airplane was obvious or that since kites fly, the airplane was obvious, etc. When the light bulb was invented, it might be argued that electricity was already understood, as was the nature of light. Therefore the light bulb was not new because it merely turned electricity into light. That kind of reasoning betrays a lack of the nature of invention.
Group 2: Fish states that ATC claims: "It's not a speaker."
In rebuttal he says, "It is."
Response: Fish claims that HSS compresses air molecules just as a speaker does. They state that HSS uses "precisely the same sound production mechanism used by everything from crystal earphones to boom-box stereos."
This statement is misleading. The audible sound that is created using HSST technology is not emitted directly by the ultrasonic transducer. The transducer only emits silent ultrasonic waves. The air itself (due to nonlinearity) is the direct source of the audible sound, hence the speaker. This is in stark contrast to the direct radiating surface of all conventional speakers.
Group 3: Fish states that ATC claims: "It's science."
He then states, "HSS is in fact science, and that is precisely its problem."
Response: Fish agrees that it is science. He argues that this is a problem because Physics 101 says, "In a closed system, energy must be conserved. In other words, you cannot get out more than you put in." He is only partly correct-- of course you do not get something for nothing.
This is not an issue because ATC does not expect nor claim more than 100 percent efficiency; a mere ten percent would be a breakthrough for sound reproduction since conventional loudspeakers are typically less than 1 percent efficient.
Efficiency in a speaker is the following ratio: acoustical power out divided by electrical power in. By obtaining better than a 1 percent efficiency, ATC is clearly not claiming to get something for nothing.
Group 4: "It's better."
Response: A list of 8 reasons as to why they believe the technology cannot be better than conventional methods is given. Here they are:
"a. Commonly available consumer ultrasonic transducers such as those possibly used in the prototype generate milliwatts of power, not the tens or hundreds necessary for high-fidelity sound reproduction."
Response: Both true and false. True, ATC's prototype transducers only consume a small amount (milliwatts) of power. False, it does not take tens or hundreds of watts of acoustical power to create hi-fi sound. The tens or hundreds of watts mentioned is how much must be used to drive a loudspeaker, not how much one gets out. Remember what efficiency is.
Physics 102 teaches that a single watt of acoustical power represents a LOT of sound. For instance, if all the residents of New York City were to talk at the same time, the total sound (acoustical) power produced would only be on the order of 100 watts.
"b. The human ear is about 10% as sensitive to bass sounds as it is to midrange. These are the sounds that are most challenging for speaker manufacturers to produce, and precisely the sounds that HSS is least equipped to handle."
Response: The HSS transducers themselves don't need to make bass or any other frequencies directly. They only emit ultrasonic waves (no bass, in fact no audio in any direct sense) that drive the air into a non-linear motion and thereby cause bass as well as the other frequencies to be generated.
"c. Production ultrasonic transducers are designed for single frequency operation and are very high Q. (frequency response in lousy)."
Response: That's often true. So what! Lawn mower wheels don't work very well on a car. They were not designed for that purpose, so it's not a real problem. Since this IS a new technology there are no off-the-shelf transducers made for this application, yet.
Purpose-built transducers, however, can have plenty of frequency response. A conventional tweeter can be made to operate from 3kHz to beyond 20kHz (which is 3 octaves). If operating in the 200kHz range, a transducer will only need 0.1 octave of frequency response to cover the entire audible range. Some electrostatic designs operate from 200kHz to more than 2Mhz. Functioning prototypes already demonstrate that this will be no problem.
"d. Ultrasound attenuates rapidly in the air. (The air absorbs sound.)"
Response: So what! You aren't listening to the ultrasound anyway. What is important is that new tones, that have an independent existence are created. I you like you can prove this by placing an acoustical filter in front of the emitters and even though the ultrasonic wave is filtered out, the audio continues on its way.
"e. Ultrasonic amplifiers are harder to design. HSS will require driver electronics to operate significantly above the 20Hz-20,000Hz range of audible reproduction."
Response: Baloney. Power amplifiers in even the cheapest CB radios operate at over 27 million cycles and put out watts of power. Such devices are commonplace. Additionally, our prototypes operate just fine with conventional audio amps that happen to have a lot more bandwidth than they need.
"Any amplifier has a speed/power product which determines its frequency response and the amount of power output. This means that if you double the frequency, you halve the available power. By going from 20kHz to 200kHz an amplifier will have one tenth as much power available."
Response: The point is only valid when speaking of an amp that goes from 20Hz to 200kHz. ATC's amp need only have a frequency response of 200kHz to 220kHz (a 10% bandwidth).
"Much of the available power in high-fidelity amplifiers is used in negative feedback to correct for distortion. If power is diverted away from negative feedback, distortion will increase. A class A amplifier running without negative feedback can produce distortion in the 5-7 percent range. This is very low fidelity."
Response: HSS uses so little power that there is no need to divert from negative feedback. The transducers use a fraction of the power that a conventional woofer uses. This would seem to be another problem that has more bearing on conventional sound reproduction methods.
"f. *********************** IMPORTANT ***********************
ATC is apparently aware of the power problem and is building a new prototype. In order to overcome the power and attenuation problems, they may be tempted to build powerful drivers and couple them to powerful ultrasonic transducers. The technology exists to build 1kW ultrasonic systems. They are expensive, and they are called ultrasonic welders.
"Such a system could be incorporated into an HSS speaker. A 200kHz HSS speaker will dissipate most of its energy in air friction within six feet of this radiator. This means the area in front of a 1kW `HyperSonic' speaker will be similar to sitting in front of a microwave.
"It's going to get really hot.
"This is a substantial health risk, particularly for small children. There is no indication from the public documents that anyone at ATC appears to have the slightest clue of this potentially life threatening risk."
Response: There are several errors here. HSS is more efficient hence less power can be used than in a conventional system, for any given sound level.
A welder is out of the question. Welding equipment is of no worth in this application; their transducers do not couple to the air. On the other hand, there are 1kW home speaker systems available today and they dissipate their heat in a confined area without any problems. Also, if this technology were dangerous to small children, it would be dangerous to all people.
In fact, high frequency ultrasound is used to image unborn babies every day because it is harmless. In a sonogram, the transducer is coupled directly to the body. An impedance matching gel is used that serves to couple even MORE of the ultrasonic energy to the fetus. Their statements are merely scare tactics from the uninformed.
"g. Ultrasound tends to form beams and ultrasonic transducers sort of look like point sources. Orchestras in concert halls are not point sources. The speakers that reproduce them had better not be either."
Response: The microphones that are used in recording an orchestra are point receivers. A microphone detects what is happening at a point, and it does not care how big the orchestra is. Your ear is also a point receiver. Playing a sound recorded by a tiny microphone element though a large speaker introduces spatial distortion. Thank goodness we don't need speakers the size of an orchestra for hi-fi. Who has the floor space?
`h. Ultrasonic beams tend to diffract (bend) around objects. Every chair, bookcase, pencil sharpener in a room could look like a source and produce the effect if sitting in a poorly designed concert hall.
Response: Wrong again. Ultrasonic beams diffract much less than do longer wavelengths. Hold your hand in front of a tweeter and you will notice that the highs go away because you create an acoustic shadow. If you do the same thing with the woofer, the sound doesn't change at all. It is the longer wavelengths that bend around things.
Because of this fact, room acoustics greatly influence the way a conventional speaker sounds. With HSS you can avoid much of the multipath and room interactions because it has a high directability. (See group five which contradicts 4h.)
Group 5: "HSS technology has the ability to manipulate the apparent source of the sound."
"True but it's a negative. ATC claims the ability to manipulate the apparent source of the sound. This is in fact true and is an artifact of ultrasonic waves tending to form in beams. This is how sonar works. It is also the same phenomenon which causes tweeter dead spots in poorly designed high-fidelity speaker systems."
Response: More control and choice over sound dispersion patterns is helpful. Versatility is never a negative.
The critic next claims that the audible difference frequency is PROBABLY not produced by nonlinearities in the air.
There is no doubt in scientific circles that sum and difference frequencies can be created in the air, even when using audible tones as the source. The phenomenon is well documented in acoustics texts and journals. A related topic, the scattering of sound by sound, also predicts sum and difference frequencies. HSS does not cheat the laws of nature, it takes advantage of them.
Fish/Mehr are correct in their Walkman Test argument. Small speakers (in the case of HSS, small ultrasonic columns) equals less bass when the source is some distance away from your ear. That will always be true. However, HSS can make more bass at a given distance, with a given size, than can conventional methods.
Fish/Mehr then return to the ultrasonic attenuation issue. Again, the signals are silent so they will not be missed.
They state that at 20 feet, a 200kHz signal will only have 0.001 of its energy left so at twenty feet away, 1000 times more energy is needed to have the same audio level that you would get up close. This is not the case. The audible frequencies that are made near the transducer face propagate with but little attenuation because they ARE audible frequencies. They don't need the `mother' wave anymore.
Fish/Mehr again express their power concerns. And repeat several concerns that were listed in his numbered topics.
The fact remains that HSS uses less power than conventional systems.
It is then stated that they have been unable to find any commercially available 200kHz transducers for air.
That's why they are being custom made. Since the application IS new, transducers for this application are new.
Fish/Mehr then ask the question, "Why ultrasonic?"
There are several apparent reasons. Higher efficiency, no need for boxy cabinets, no crossover networks, no woofers, no cones, no magnets or magnetic shielding, no high current amplifiers, 10 octave bandwidth using only 0.1 octave amplifiers and transducers, no floor space requirements, powerful control over directionality and sound placement, sound projection and special effects...
Fish/Mehr say the ability to generate sound from ultrasonic transducers is not new and it is not unique. If others have achieved ATC's success, where are their products.
Fish/Mehr then say that "Somebody at ATC clearly does not understand what happens to ultrasonic signals in air..." He then claims that to fill a football stadium with equivalent sound intensity with a 200kHz signal, 1.8 x 10 to the 75th power watt is needed."
Again, the self-appointed experts display a lack of understanding of the technology. A stadium would not need to be filled with ultrasound. Only audible sound.
Then they attack the inventor and his lack of a formal degree. Education and ingenuity are independent of each other. Thomas Edison had only 3 months of formal schooling. Bill Gates is a college drop out. Numerous Ph.D.'s have seen and experienced what ATC is doing and have called it everything from astonishing to brilliant to incredible.
Mr. Norris has numerous patents both issued and pending (for a complete list by patent number, date and descriptions see ATC's website at: www.atcsd.com); his credentials as an inventor are indisputable.
As for Fish's credentials, see www3.techstocks.com/~wsapi/investor/s-1954/reply-1471.
Side note: Over the past several months Carl Mehr has shown a relentless, but unexplainable interest in both Mr. Norris and the HSS project. Mr. Norris says he has no idea who the man is. One might well ask why he spends so much time thinking and writing about something he is sure will fail? If he really believes it will not amount to anything, why waste his time? The free market rewards worthy products and the rest never see the light of day. An explanation of his motives would be appreciated.
In conclusion, let it be stated that it has ever been easy to show your own greatness by putting up a straw man and then knocking it down.
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Ty |
