1、 SURFACE VEHICLE RECOMMENDED PRACTICE Operational Sound Level Measurement Procedure for Snow Vehicles SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its a
2、pplicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments
3、and suggestions. Copyright 2004 SAE International All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE.
4、TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: custsvcsae.org SAE WEB ADDRESS: http:/www.sae.org J1161 REV. APR2004 Issued 1976-11 Revised 2004-04 Superseding J1161 MAR1983 1. Scope This recommended practice establishes t
5、he instrumentation, test site, and test procedure for determining the exterior operational sound level for snowmobiles. 2. References 2.1 Applicable Publications The following publications form a part of the specification to the extent specified herein. Unless otherwise indicated the lastest revisio
6、n of SAE publications shall apply. 2.1.1 SAE PUBLICATION Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. SAE J184NOV98Qualifying a Sound Data Acquisition System 2.1.2 ANSI PUBLICATION Available from ANSI, 11 West 42nd Street, New York, NY 10036-8002. ANSI S1.4A 1983 (R-2000)Sp
7、ecification for Sound Level Meters 2.2 Related Publications The following publications are provided for information purposes only and are not a required part of this document. 2.2.1 ANSI PUBLICATIONS Available from ANSI, 11 West 42nd Street, New York, NY 10036-8002. ANSI S1.11994 (R-1999)Acoustical
8、Terminology Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1161 Revised APR2004 - 2 - 3. Instrumentation The following instrumentation shall be used, where applicable, for the measurements requ
9、ired: 3.1 A precision sound level meter which meets the Type 1 requirements of American National Standard Specification for Sound Level Meters (S1.4 A-1985 (R-2000). 3.1.1 As an alternate to making direct measurements using a sound level meter, a microphone or sound level meter may be used with a ma
10、gnetic tape recorder and/or graphic level recorder or indicating meter providing the system meets the requirements of SAE J184, Qualifying a Sound Data Acquisition System. 3.1.2 The microphone shall be used with a windscreen that will not affect the microphone response by more than 1 dB for frequenc
11、ies of 204000 Hz or 1.5 dB for frequencies of 400010 000 Hz at zero wind speed conditions. 3.2 An acoustic calibrator (accuracy within 0.5 dB). 3.3 A calibrated vehicle speed indicating system (accuracy within 5% at test speed). 3.4 A thermometer (accuracy within 1 C 2 F). 3.5 A barometer (accuracy
12、within 1%). 3.6 A psychrometer or dew point apparatus. 3.7 An anemometer (accuracy within 1%). 3.8 A windvane or other device for the measurement of wind direction. 4. Test Site 4.1 A suitable test site is a level open space free from the effects of large sound reflecting surfaces. Parked vehicles,
13、signboards, and other obstacles must not be located within 30.4 m (100 ft) of either the vehicle path or the microphone (Figure 1). Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1161 Revised A
14、PR2004 - 3 - FIGURE 1UNIDIRECTIONAL TEST SITE LAYOUT 4.2 The microphone shall be located 15.2 m (50 ft) from the centerline of the vehicle path and 120 cm (48 in) above the snow or turf. The normal to the vehicle path from the microphone shall establish the microphone point on the vehicle path. 4.3
15、The measurement area shall be the triangular area formed by the start point, the end point, and the microphone location. 4.4 The surface of the ground within the measurement area, including the vehicle path, shall be covered with a maximum of 7.5 cm (3 in) loose snow over a base consisting of at lea
16、st 5 cm (2 in) of snow sufficiently compacted to support the snowmobile without penetration. As an alternative, a surface of turf, primarily grass up to a maximum of 7.5 cm (3 in) in height may be used, which, except for the vehicle operating path, shall be free of visible droplets of water. 4.5 The
17、 reference point of the vehicle, to indicate when the vehicle is at any of the points on the vehicle path, shall be the front of the vehicle skis. 4.6 While making sound level measurements, not more than one person, other than the observer reading the meter and the test driver, shall be within 15.2
18、m (50 ft) of the vehicle path or microphone and that person shall be directly behind the observer reading the meter on a line through the microphone and observer. 4.7 The ambient A-weighted sound level (including wind effects) coming from sources other than the vehicle being measured, shall be at le
19、ast 10 dB lower than the noise level with the vehicle operating under test conditions. 5. Procedure 5.1 Vehicle Operation 5.2 A constant speed as specified below is the basis for determining the operational sound level of the snowmobile. Copyright SAE International Provided by IHS under license with
20、 SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1161 Revised APR2004 - 4 - 5.2.1 Before reaching the start point, accelerate the vehicle to the speed of 24 3 km/h (15 2 mile/h). Maintain this constant speed with throttle held as steady as possible through
21、to the end point. The centerline of the vehicle must not deviate more than 1 m (3 ft) from either side of the centerline of the vehicle path. 6. Measurements 6.1 The sound level meter shall be set for slow response and the A-weighted network. 6.2 The applicable sound level reading shall be the highe
22、st indicated for the run, between the start point and the end point, ignoring unrelated peaks due to extraneous noise. 6.3 During the test period, the atmospheric temperature, pressure, humidity, wind speed, and wind direction shall be recorded at intervals not to exceed 1 h. Also record test surfac
23、e conditions. 6.4 Test runs shall be repeated until three readings within a 2 dB range per vehicle side have been obtained. The sound level for each side of the vehicle shall be the average of all three readings, rounded to the nearest integer. The sound level reported shall be that for the side of
24、the vehicle with the highest average. 7. General Comment 7.1 It is recommended that persons technically trained and experienced in the current technique of sound measurement select the equipment and conduct the tests. 7.2 The operation of recording and measuring equipment is likely to be affected by
25、 low temperatures. Where measurements are undertaken at temperatures near or below 0 C (32 F), special precautions must be taken to ensure the reliability of sound meter readings and/or recordings. 7.3 Instrument manufacturers specifications for the proper use of all the test equipment shall be adhe
26、red to. 7.4 Measurements shall be made only when the wind speed is below 19 km/h (12 mile/h) and absolute barometric pressure is between 93 and 103 kPa (27.5 and 30.5 in of mercury). 7.5 The vehicle manufacturers recommendation governing the proper operation of the vehicle shall be followed. 7.6 Pro
27、per acoustical calibration procedure shall include the influence of extension cables, etc. Field calibration shall be made immediately before and after each test sequence. Internal calibration means is acceptable for field use, provided external calibration is accomplished immediately before and aft
28、er field use. 7.7 A 2 dB tolerance over the sound level limit shall be included to provide for variations in test sites, temperature gradients, wind velocity gradients, test equipment, and inherent differences in nominally identical vehicles. Copyright SAE International Provided by IHS under license
29、 with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J1161 Revised APR2004 - 5 - 8. Notes 8.1 Marginal Indicia The change bar (l) located in the left margin is for the convenience of the user in locating areas where technical revisions have been made to the
30、 previous issue of the report. An (R) symbol to the left of the document title indicates a complete revision of the report. PREPARED BY THE SAE SNOWMOBILE SUBCOMMITTEE Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without lice
31、nse from IHS-,-,-SAE J1161 Revised APR2004 Rationale 1. Introduction: 1.1 This subcommittee was charged with the task of writing a test procedure for measuring snowmobile operational sound levels. Previous procedures for measurement of the exterior sound levels of snowmobiles, SAE J192 and SAE J192a
32、, produced only maximum sound levels, a fact which was often misunderstood. 2. Summary Of Results: 2.1 The Procedure for Measuring Operational Sound Levels is based on SAE J192a, utilizing the experience gained in the writing of that procedure, since all aspects of the present procedure except the a
33、ctual vehicle operation could be similar. A series of field tests conducted by members of the subcommittee to obtain data on the relationship of trail speed to trail time, combined with other data on vehicle usage, firmly established that the average speed of operation of a snowmobile in normal use
34、was between 16 km/h (10 mile/h) and 24 km/h (15 mile/h). A constant speed passby at 24 km/h (15 mile/h) on a SAE J192a type test site was, therefore, selected for this procedure. 3. Discussion: 3.1 This document is intended to specify a procedure by which the operational sound level produced by a sn
35、owmobile may be measured. Experience has shown that the maximum noise procedure J192a does not adequately represent the noise impact of all snowmobiles. For instance, economy model snowmobiles produce higher noise levels at low speeds when compared to family and sport models. 3.2 The instrumentation
36、 required by this procedure is necessary to provide comparable data from an outdoor test of a moving vehicle operated on natural surfaces. Test surface specifications and atmospheric parameter specifications are intended to insure repeatability of test results. A maximum rms holding meter is permitt
37、ed under 3.1. A radar speed measuring device, “speed gun“, or fifth wheel device is permitted under 3.3 to facilitate measurement, especially for vehicles not normally equipped with speedometers. 3.3 The test surface specified in SAE J192a was used in this procedure because it represents the most na
38、tural snowmobile operating surface which will provide repeatable test results. The test operating mode of a constant speed passby at moderate speed was readily accepted by the committee members on the basis of the trail ride data available which clearly indicated that the majority of the time the sn
39、owmobile was in operation was spent at under 32 km/h (20 mile/h). The speed of 24 km/h (15 mile/h) on which agreement was finally reached represents the best choice. Representative test reports of trail ride data submitted by subcommittee members have been included to support this choice. 3.4 A mini
40、mum number of three runs resulting in sound levels within 2 dB for each vehicle side have been specified in the procedure. This number of runs is deemed necessary to insure valid, repeatable test results. A reduced number of runs may be considered if the objective is a simple screening of a large nu
41、mber of vehicles, but the results must not then be considered comparable to data from the procedure as written. 3.5 It might be noted in support of an operational sound level procedure that the initial problems caused by early snowmobiles have subsided as a natural consequence of the work already pe
42、rformed to reduce snowmobile sound levels. The procedure for measuring snowmobile operational sound levels provides a repeatable, easy to perform test to supplement SAE J192a. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted with
43、out license from IHS-,-,-SAE J1161 Revised APR2004 Relationship of SAE Standards to ISO Standard Not applicable. Application This recommended practice establishes the instrumentation, test site, and test procedure for determining the exterior operational sound level for snowmobiles. Reference Sectio
44、n SAE J184NOV98Qualifying a Sound Data Acquisition System ANSI S1.4A 1983 (R-2000)Specification for Sound Level Meters ANSI S1.11994 (R-1999)Acoustical Terminology Developed by the SAE Snowmobile Subcommittee Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
