1360 Technical Notes and Research Briefs 1360

The new regulations are aimed particularly at heavy trucks and other vehicles with unnecessarily noisy exhaust systems, "singing tires," and other noise-producing equipment. They are applicable to owners and drivers alike, as well as to all Turnpike vehicles, and establish maximum acceptable noise limits which can be accom- plished with "minimal effort and expense."

William J. Flanagan, executive director of the Turnpike Author- ity, said that even though 97% of all Turnpike users will have no difficulty in meeting the limits, the far-reaching decision was taken for several reasons:

"The regulations will produce meaningful noise reductions for our neighboring communities, even in the face of increasing traf- fic; will only require vehicle changes and repairs that are technol- ogically available and economically reasonable; and will permit workable police enforcement.

"Since a large percentage of our patrons are interstate travelers, we also anticipate our regulations will cause a general reduction in traffic noise along every major highway throughout the entire east- ern seaboard.

"They are similar to those successfully enforced in California and Chicago, and are consistent with those proposed and likely to be adopted by the U.S. Environmental Protection Agency (EPA) for heavy vehicles operated in interstate commerce.

"Several other jurisdictions have adopted limitations on vehicle noise in recent years, but they have done little to reduce noise levels because they have not been generally enforced. We intend from the outset to make ours work," Flanagan asserted.

Effective 1 June, heavy trucksmany vehicle with six or more tires and rated in excess of 10000 lbswill be limited to a maximum

of 90 decibels (dBA) at 50 ft at existing speed limits, with provi- sion for reductions to 84 dim in 1978 and 78 dBA in 1990.

Stricter limits will apply on ramps and in toll plazas and service areas.

Although other classes of vehicles do not generally produce as much noise, the Turnpike regulations also set separate limits for those under 10000 lb--light trucks and carsmand motorcycles. A properly maintained car traveling at 55 mph generates less than 80 dBA.

The decibel is the standard for measuring sound pressure, or in other words, noise levels. Decibel levels will be measured by road- side microphones and monitoring equipment, certified to be accu- rate, in accordance with standard specifications.

Turnpike officials do not expect enforcement to be a problem. Operators will receive extensive training prior to certification and sophisticated monitoring equipment will be placed at any of sev- eral approved sites, each predetermined to provide accurate read- ings. Violators will be issued summonses' by State Police and can be fined up to $200.

There will be a short "grace period" during which State Police will issue warnings rather than summonses. This will enable Turn- pike patrons operating excessively noisy vehicles to take remedial action or run the risk of being cited during future trips.

A survey taken on the Turnpike last September by Bolt Beranek and Newman Inc., of Cambridge, Massachusetts, the Authority's noise consultants, showed that about 82% of nearly 1500 trucks and buses monitored would meet initial limits, the same as enforced in California and Chicago in 1972.

The heavy vehicle limits scheduled for the Turnpike in 1975 are identical to those now enforced in those places, and are the same limits EPA plans to have in effect next year.

Of the vehicles cited in California in 1973 under these limits, 78% had modified or inadequate exhaust systems, 21% defective systems, and the remainder such problems as defective engines and excessively noisy tires.

Future reductions are based on the orderly replacement and re- fitting of truck fleets to include quieter mufflers, tires, fans, and engine enclosures. Virtually all deficiencies can be remedied for less than the cost of the potential fines.

Motorcycles may show a high percentage of violations because stock models are frequently modified by their owners deliberately to make more noise.

The regulations also prohibit the use of the Turnpike by vehi- cles with a number of deficiencies that can be detected visually. Included are improper exhaust systems, certain types of noisy tires and any vehicle with a vertical exhaust stack pointing to the right.

Printed copies of the regulations will be available at the Turn- pike Authority's East Brunswick headquarters.

Newly published American national standards [15.10]

The acoustical standards listed below are available from the

American National Standards Institute, Sales Department, 1430 Broadway, New York, N.Y. 10018, at the prices indicated.

S3.20-1973, "Psychoacoustical Terminology" $3.25 S6.1-1973, "Qualifying a Sound Data Acquisition

System" (SAE RPJ184) $2.25 S6.2-1973, "Exterior Sound Level for Snowmobiles"

(SAE RPJ192) $2.25

Captioned TV for deaf on display [70.55; 65.10]

A new "captioned TV system" invented by the Commerce Department's National Bureau of Standards to broaden the com- munications horizons of the deaf is on display at the Smithsonian Institution's Museum of Science and Technology in Washington, D.C., through October 1974.

The system, which distills dialogue on a television sound track into printed words at the bottom of the screen, was developed by the NBS Time and Frequency Division at Boulder, Colorado. Join- ing in the effort were the Public Broadcasting System and the De- partment of Health, Education and Welfare.

The captioning system is part of an exhibit on "American Re- habilitative Medicine" being presented in the West Wing of the museum, located at Constitution Avenue and 13th Street.

Americans with impaired hearing number in the tens of millions, and derive little good from existing television entertainment, news, weather warnings, and other programs. However, viewers with normal hearing don't want their screens cluttered with superfluous captions.

The solution offered by the NBS system provides captions only to those who need them. The captions are sent in code along with the picture but are not seen unless a special decoder circuit is ac- tivated. They appear similar to the subtitles on foreign movies shown in this country. Regular programming is not affected in any way, and the captions can be turned on or off at will in sets equipped with decoders. .

Decoders could be installed today in new television sets during manufacture for $100 to $150, depending on the size of the pro- duction run. This price should decrease materially over the next five years. Converting an existing set to receive the captions is sometimes possible, but would cost much more.

The captions could be transmitted over the national networks or originated by local broadcasters, or both. A petition is present- ly before the Federal Communications Commission requesting per- mission to broadcast the coded captions nationwide. If this is approved, NBS will work closely with those national networks that agree to begin providing the service, and with manufacturers who wish to include decoder circuits in their television sets.

Technical reports [10.50]

The following technical reports may be obtained from the Na- tional Technical Information Service, Springfield, Virginia 22151, under the order numbers given, unless otherwise noted.

Lectures on Marine Acoustics. Volume I. Fundamentals of

Marine AcousticsmJ. W. Caruthers (Ed.), Department of Oceanog- raphy, Texas A &M University, College Station, Texas. This is the first of two volumes representing compilations of lectures presented at the short course in Marine Acoustics held at the Department of Oceanography of Texas A&M University in 1971. The introduction reviews sound in the sea, nature of the acoustic field, logarithmic units, and spectral notions. Subsequent sections deal with the fol- lowing: electroacoustic and chemical transduction; hydrophones, projectors, and calibration; arrays and systems; sonar equations and parameters; theory of sound propagation; sound propagation in the sea; reverberation; and finally, noise. [(Sinha, OEIS) Order No. COM-73-11369.]

J. Acoust. Soc. Am., Vol. õõ, No. 6, June 1974

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