TECHNICAL NOTES AND RESEARCH BRIEFS

nificant difference in soil temperature be- tween the two cabinets. Increased microbe

activity should change the acidity of the soil. A careful check of soil acidity at the end of the experiment indicated a pH of between 3.5 and 4 in all pots."

Miss Harowitz performed two other simi- lar experiments to see whether one of the common auxins (growth-promoting plant hormone), 3-indoleacetic acid (IAA), might

be involved in producing the effects. These were not conclusive, insofar as the involve- ment of IAA was concerned. However, the ultrasonically treated plants again showed greater growth in each case.

As a final experiment, the growth of a set of normally lighted control plants was com- pared with the growth of a set of plants de- prived of light, but exposed to ultrasonic radiation. The average growth of the

ultrasonically treated plants was markedly greater at all times after sprouting, and after 20 days the insonified plants were 134% taller than the controls. The control plants were sturdy with thick stems and bright green leaves; the treated plants were spindly, thin stemmed, and yellowish?-•

• Stong, C. L., 1966 "The Amateur Scientist," Sci. Am. 215, 100-102.

5.1

ACOUSTIC DEVICE TO IMPROVE FUEL COMBUSTION

A NEW TECHNIQUE THAT MAKES USE OF

acoustic energy to improve liquid and gase- ous fuel combustion processes and, at the same time, reduce exhaust by products, has been developed by Acoustica Associates, Inc. Several forms of this simple, inexpen- sive device have been designed for auto- mobile engines, industrial furnaces, and other burners and carburetion systems. Ac- cording to a press release, the new technique increases the efficiency of combustion, re- duces fuel consumption, and lessens the

emission of exhaust produces, including un- burned fuel and carbon monoxide.

The devices are completely static, having no moving parts, electrical or electronic components, and can be installed easily in many existing burners and carburetors with little or no modification. It is reported that, "Road tests of the units in a number of automobiles show fuel savings of up to 12%, accompanied by reductions in the amounts of unburned hydrocarbons and carbon monoxide released to the atmo-

sphere. Smaller engines, such as those used in lawn mowers, can be operated at full efficiency using lower grade fuels, including kerosene, in conjunction with one form of the new device."

The technique applies acoustic energy to the fuel-air mixture at or near the burning zone or cylinder to mix the two combustion components together more thoroughly. When used with liquid fuels, the acoustic device can improve upon or eliminate com- pletely the regular engine carburetor by atomizing fuel droplets into a fine fog that burns more efficiently in contact with air. With gaseous fuels, such as natural gas, the enhanced combustion process again in- volves the use of an acoustic energy field to mix fuel and oxygen molecules more inti- mately. It is planned to market the devicsc initially to original equipment manufae- turers, governmental users, and utilities.•

10.3

COLORS FROM SOUND

MOST SOUND COMES to the human ear as

variations in frequency. But, to the bio- medical engineers at Northwestern Uni- versity's Technological Institute, sound is seen as colors--such as blue, purple, orange, or red.

In actuality, Dr. John E. Jacobs, execu- tive director of the institute's Biomedical Engineering Center, and his co-workers de- veloped what is probably the first ultra- sonic imaging system capable of producing

x-ray-like colored images of any living tissue on a color-television screen.

We can show clearly discernible blood vessels in a finger, for example, that appear as pulsating green or blue or orange lines, Jacobs told Industrial Research.

However, he explains, the colors do not represent real colors of the hand's internal structure. Instead, they show varying rates at which sound waves pass through the hand when it is dipped in a water tank in the path of the sound waves.

Black-and-white television sonic imaging systems--also developed by Jacobs--have

been around for some years. The color system, however, represents an increased sensitivity of from 20 to 40 times, simply because the eye can recognize nearly100 dif- ferent shades of color at the same brightness as compared to about five in black-and- white television.

Future uses lie both in the medical and

industrial areas, he believes. The device could be quite valuable in nondestructive testing to identify defective spot welds. A good weld shows up as one color; a bad weld as a wild variation.•

(Industrial Research, Jan. 1968, p. 32.)

16.3, 16.4

LOOK OUTInHERE COMES "1984!"

FINDINGS OF EXPERIMENTS at Northern

Illinois University suggest support of the old wives' tale that a newborn human infant can recognize his mother's voice. In work reported by O. B. Grier, S. A. Counter, and W. M. Shearer, • "A batch of eggs was exposed to a patterned sound continuously from day 12 to day 18 of incubation, while a control group was hatched in the quiet. In a postnatal test all chicks tended to creep toward a stationary sound source, but the experimental group showed a pref- erence for the sound heard during incuba- tion. In a second test the experimental chicks followed a moving model longer when

894 Volume 43 Number 4 1968

it emitted the familiar sound than when it emitted a novel sound or no sound at all.

"Newly hatched chicks seem to find any sound attractive, but a sound heard during the prenatal period proved more attractive than a novel one in two tests. In the second

test the imprinted chicks even occasionally tried to jump on the toy model to get to the speaker. The results of these tests do not seem attributable to a natural preference for lower-frequency stimulation, since chicks in the control group found both the 200-Hz and 2000-Hz patterns equally at- tractive. Thus, young chicks are able to re- spond differentially to a sound heard pre- natally. One possible explanation of the results of the following test could be that the sound merely called attention to the model,

so that the following was primarily a re- sponse to a visual form. But since the model was passed directly in front of the chick several times it is unlikely that the chick could not see it. These studies indicate that

the auditory system functions considerably prior to hatching, and perhaps more im- portant, that auditory events during the prenatal period can influence immediate postnatal preferences and behavior. To the extent that the term imprinting implies the ability to use this earlier exposure to stimuli as a basis for later behavior such as recog- nition, attraction, or following, we believe that the experiment demonstrated prenatal auditory imprinting."•

• Grier, O. B., Counter, S. A., and Shearer, W. M. 1967 Science 155, 1692-1693 (31 Mar.).

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