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                               SCC’ETY OF AUTOMOTIVE EN INFERS, »NC.  TWO PENNSYLVANIA PLAZA • NEW YORK, NE.7  o  X  I0CG1
                                                                                                                     r ‘ 1


                                SOCIETY OF AUTOMOTIVE EN  INFERS, INC. 1963. THIS  UJ  (X   ORT ’S SCHEDULED FOR THE 1959 SAE HANDBOOK.
       hOUND -LEVEL "FOR
                              PASSENGER CARS
       AN DELIGHT' TRUCKS     — SAE J936a                                         SAE Standard

       Report of Vehicle  r.  c  E 2  t  approved July 1967 and last revised by Vehicle Sound Level Committee July 1968.
         t. Scope—This SAE Standard ofablishcs the maximum sound lexel   4.22 Wheel slip which affects the maximum sound lex el must he
       for passenger cars and light trucks and describes the test procedure,   avoided.
       environment, and instrumentation for determining this sound level.  4.2.3  The engine temperature shall be within the normal operating
         2.  Sound Level Limit—The sound level produced by a new pas­  range throughout each run. A 1 minute cooling off period with engine
       senger car or light truck of 6000 gvw or less shall not exceed 86 db.   at idle in neutral is required between runs.
       on an A-weighted network at 50 ft when measured in accordance with   4.3  Measurements
       the procedure described herein. {See paragraph 5.2 for field measure­  4.3.1  The microphone shall be located 50 ft from the tentetline oi
       ments.)                                                   the vehicle path at a heigh: of 4 ft above the ground plane.
        . 3. Initrumenlation—The following instrumentation shall be used for   4.3.2  The meter shall be set for fast response and the A-weighted
       the measurement required:                                 network.
           3-1 A sound level meter which meets the requirements of Inter­  4.3.3  The meter shall be observed while the vehicle is accelerating'
       national Electrotechnical Commission Publication 179. Precision Sound   The applicable reading shall be the highest sound level obtained-'foi
       Level Meters.                                             the run, ignoring unrelated peaks due to extraneous ambient noises. At
         3.1.1  Alternatively, a microphone magnetic tape recorder indicating   least tworneasurements shall be made for each side of the vehicle. AU
       meter system, whose overall response is equivalent to the above, may   values should be recorded.
       be used.                                                    4.3.4  The sound level for each side of the vehicle shall be the
           32 A sound level calibrator (see paragraph 5.5).      average of the two highest readings which are within 2 db of each
           3.3  A calibrated windscreen or nosecone (see paragraph 5.4).  other. The sound lev el reported shall he that of the loudest side of the
           3.4  An engine-speed tachometer.                      vehicle.
         < Procedure                                               5.  General Comments
           4.1  Test Site—A suitable test site, which could be considered ideal   5.1 It is stronglv recommended that technically trained pcis< i'.tiel
       for purpose of measurements, shall consist of a fiat open space free of   select the equipment and that the tests he conducted only by qua.di-.id
        large reflecting surfaces (such as signboards, buildings, or hillsides)   persons trained in the current techniques of sound measurement.
       located within 100 ft of either the vehicle or the microphone.  5J2 A 2 db allowance for the sound fest! limit is necessary to
         4.1.1  During the measurement, the surface of the ground within the   provide for variations in tot site, vehicle operation, temperature
         easurement area shall be free from powdery snow, long grass, loose  gradients, wind velocity gradients, test equipment, and inherent dif­
       Moil, or ashes.                                           ferences in nominally identical vehicles.
         4.122 Because bystanders mas base an appreciable influence on meter   5.3  Instrument manufacturer’s specifications for orientation of the
        response when they are in the vicinitv of the vehicle or the micro­  microphone relative to the source of sound and the location of the
        phone. no person other than the observer reading the meter shall be   observer relative to the meter, should be adhered to.
       near the vehicle or the microphone.                          . 5.4 When a windscreen is required, a previously calibrated wind­
         4.1.3  The ambient sound level (including wind effects) due to   screen should he used. It is recommended that measurements he made
       sources other than the vehicle being measured shall be at least 10 dbA   only when wind velocity is below 12 mph.
        lower than the level of the tested vehicle.                  5-5 Instrument manufacturer's recommended calibration should
         4.1.4  The path of vehicle travel shall be relatively smooth, dry con­  be made at appropriate times. Field calibration should be made im­
       crete or asphalt, free of extraneous materials such as gravel.  mediately before and after each test sequence Either an externa! cali­
           42 Vehicle Operation                                   bration or internal calibration means is acceptable for field use. pm-
         42A From an approach speed of 30 mph, wide-open throttle shall   vided that external calibration is accomplished before and after field
        be established when the front of the vehicle reaches a line 25 ft before   use.
        a line through the microphone norma’ to the vehicle path. Use the   5.6 Vehicles used for tests must not be operated in a manner such
        lowest transmission gear or range such that the front of the vehicle   (hat the break-in procedure specified bv the manufacturer is xiohiteu
        will base reached or passed a line 25 ft beyond (he microphone line   6.  Kcfrrrure.s—Suggested reference material is as follows:
        when maximum rated engine speed1 is reached. The throttle shall then   1.  USA SI SI J-I960, Acoustical Terminology.
        be closed ertbugh to prevent excessive engine speed and the test con­  2.  USAS! S 1.2-1962. Physical Measurement of Sound.
        tinued until the vehicle reaches , a line 125 ft besond the microphone   3.  International Electrotechnical Commission Publication 179. Pre­
        line.                                                     cision Sound Level Meters. (Available from USAS!)
                                                                   (Applications for copies of these documents should be addressed to
                                                                  ITS-A. Standards Institute. 10 East 40th Street. New \ork New \oik
                                                                  10016.)
        - 6Speed at *hi<-h maximum h«ir*ej»«»urr i< rated pivrrned yperd.









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            AH technical reports, including standards approved and prac­  ?n formulating and approving technical reports, the Technical
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            mended Practice, and no commitment to conform to or b®   themselves against liability for infringement of patents
            guided by any technical report.                                                              Printed in U.S.A.
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