SMPTE EG 16-2014 Measurement Methods for Film and Digital Motion-Picture Camera Acoustical Noise - Field Method.pdf
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1、 Copyright 2014 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Plains, NY 10601 (914) 761-1100 Approved February 11, 2014 Table of Contents Page Forward . 2 Intellectual Property 2 1 Scope 3 2 Conformance Notation 3 3 Normative Reference 3 4 Definitions . 4 5 Acoust
2、ical Environment. 4 6 Instrumentation . 4 7 Camera Installation and Operation . 5 8 Measurement of Frequency and Time-Weighted Sound Pressure Level . 5 9 Limit on Acceptability 7 10 Means for Reducing Camera Noise 8 Annex A Background (Informative) 9 Annex B Bibliography (Informative) . 10 Page 1 of
3、 10 pages Measurement Methods for Film and Digital Motion-Picture Camera Acoustical Noise Field Method SMPTE ENGINEERING GUIDELINE SMPTE EG 16:2014 Revision of EG 16-2002 SMPTE EG 16:2014 Page 2 of 10 pages Foreword SMPTE (the Society of Motion Picture and Television Engineers) is an internationally
4、-recognized standards developing organization. Headquartered and incorporated in the United States of America, SMPTE has members in over 80 countries on six continents. SMPTEs Engineering Documents, including Standards, Recommended Practices, and Engineering Guidelines, are prepared by SMPTEs Techno
5、logy Committees. Participation in these Committees is open to all with a bona fide interest in their work. SMPTE cooperates closely with other standards-developing organizations, including ISO, IEC and ITU. SMPTE Engineering Documents are drafted in accordance with the rules given in Part XIII of it
6、s Operations Manual. SMPTE EG 16 was prepared by Technology Committee 20F. Intellectual Property At the time of publication no notice had been received by SMPTE claiming patent rights essential to the implementation of this Engineering Guideline. However, attention is drawn to the possibility that s
7、ome of the elements of this document may be the subject of patent rights. SMPTE shall not be held responsible for identifying any or all such patent rights. SMPTE EG 16:2014 Page 3 of 10 pages 1 Scope This guideline provides a simple method for measuring the acoustical noise output of motion-picture
8、 cameras in use on the set of a production. The guideline applies to noise occurring in only one circumstance: in front of a given camera in a specific acoustical environment. Thus, the measurements given by this guideline are not comparable with others made in different situations. This guideline a
9、lso gives limits on acceptability of measured camera noise due to the combined effects of the camera and its environment. Methods for reducing camera noise which are practicable on the set are included. 2 Conformance Notation Normative text is text that describes elements of the design that are indi
10、spensable or contains the conformance language keywords: “shall“, “should“, or “may“. Informative text is text that is potentially helpful to the user, but not indispensable, and can be removed, changed, or added editorially without affecting interoperability. Informative text does not contain any c
11、onformance keywords. All text in this document is, by default, normative, except: the Introduction, any section explicitly labeled as “Informative“ or individual paragraphs that start with “Note:” The keywords “shall“ and “shall not“ indicate requirements strictly to be followed in order to conform
12、to the document and from which no deviation is permitted. The keywords, “should“ and “should not“ indicate that, among several possibilities, one is recommended as particularly suitable, without mentioning or excluding others; or that a certain course of action is preferred but not necessarily requi
13、red; or that (in the negative form) a certain possibility or course of action is deprecated but not prohibited. The keywords “may“ and “need not“ indicate courses of action permissible within the limits of the document. The keyword “reserved” indicates a provision that is not defined at this time, s
14、hall not be used, and may be defined in the future. The keyword “forbidden” indicates “reserved” and in addition indicates that the provision will never be defined in the future. Unless otherwise specified, the order of precedence of the types of normative information in this document shall be as fo
15、llows. Normative prose shall be the authoritative definition. Tables shall be next, followed by formal languages, then figures, and then any other language forms. 3 Normative Reference The following standards contain provisions which, through reference in this text, constitute provisions of this pra
16、ctice. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this practice are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. IEC 61672-1 (2013-09), Ele
17、ctroacoustics Sound Level Meters Part 1: Specifications SMPTE EG 16:2014 Page 4 of 10 pages 4 Definitions For the purpose of this guideline, the following definitions apply: 4.1 sound pressure level, Lp , in decibels Twenty times the logarithm to the base 10 of the ratio of the sound pressure to the
18、 reference sound pressure. The frequency weighting network used shall be indicated; for example, A-weighted sound pressure level, LpA. The reference sound pressure is 20 Pa. 4.2 reference point The center of the film aperture in the camera gate, or its equivalent position in a digital camera. 4.3 me
19、asurement distance The distance between the reference point and the measurement point. 4.4 background noise The A-weighted sound pressure level at the microphone position with the camera inoperative. 5 Acoustical Environment 5.1 Criteria for Adequacy of the Test Environment Ideally, the test environ
20、ment should be free from reflecting objects other than a single reflecting plane so that the source radiates into a free field over a reflecting plane. In practice, measurement to this guideline shows the effects of the environment. No environmental correction factor is applied in order to keep the
21、measurement simple, but users are cautioned that the results are not directly comparable from one situation to another. 5.2 Criterion for Background Noise At the microphone positions, the A-weighted sound pressure level due to the background noise shall be at least 3 dB below the A-weighted sound pr
22、essure level with the source operating. (Background noise levels which are less than 3 dB below the sound level of the source to be measured are too high for the purposes of this guideline. Under such circumstances, it is not possible to determine the A-weighted sound pressure level of the source to
23、 reasonable accuracy. However, the result determined with higher background noise levels may be useful as an indication of the upper limit of the sound pressure level of the source.) 6 Instrumentation 6.1 General A sound level meter that meets the requirements of IEC 61672 shall be used switched to
24、the “impulse” characteristic. To minimize the influence of the observer on the measurements, a cable should preferably be used between the microphone and the sound level meter. The observer shall not stand between the microphone and the source whose sound pressure level is being measured. SMPTE EG 1
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