1 - AS 1217.4-1985 ACOUSTICS - DETERMINATION OF SOUND POWER LEVELS OF NOISE SOURCES - ENGINEERING METHODS FOR SPECIAL REVERBERAT
4 - PREFACE
5 - CONTENTS
7 - FOREWORD
8 - SYNOPSIS
9 - SECTION 1. SCOPE AND GENERAL
9 - 1.1 SCOPE.
9 - 1.2 FIELD OF APPLICATION.
9 - 1.2.1 Types of noise.
9 - 1.2.2 Size of source.
9 - 1.3 REFERENCED DOCUMENTS.
9 - 1.4 MEASUREMENT UNCERTAINTY.
9 - 1.5 DEFINITIONS.
9 - 1.5.1 Special reverberation test room
9 - 1.5.2 Reverberant sound field
9 - 1.5.3 Mean-square pressure
10 - 1.5.4 Sound pressure level
10 - 1.5.5 Sound power level
10 - 1.5.6 Frequency range of interest
10 - 1.5.7 Direct method
10 - 1.5.8 Comparison method
10 - 1.5.9 Volume of source under test
11 - SECTION 2. TEST ROOM REQUIREMENTS
11 - 2.1 GENERAL.
11 - 2.2 ROOM VOLUME.
11 - 2.3 REVERBERATION TIME OF TEST ROOM.
11 - 2.4 SURFACE TREATMENT.
11 - 2.5 CRITERION FOR BACKGROUND NOISE.
11 - 2.6 CRITERIA FOR TEMPERATURE AND HUMIDITY.
11 - 2.7 TEST OF ROOM SUITABILITY.
12 - SECTION 3. INSTRUMENTATION
12 - 3.1 GENERAL.
12 - 3.2 THE MICROPHONE AND ITS ASSOCIATED CABLE.
12 - 3.3 AMPLIFIER AND WEIGHTING NETWORK.
12 - 3.4 OCTAVE BAND FILTERS.
12 - 3.5 SQUARING AND AVERAGING CIRCUITS AND INDICATING DEVICE.
12 - 3.6 FREQUENCY RESPONSE OF THE INSTRUMENTATION SYSTEM.
12 - 3.7 CALIBRATION.
13 - SECTION 4. INSTALLATION AND OPERATION OF SOURCE
13 - 4.1 GENERAL.
13 - 4.2 SOURCE POSITION.
13 - 4.3 SOURCE MOUNTING.
13 - 4.4 AUXILIARY EQUIPMENT.
13 - 4. 5 OPERATION OF SOURCE DURING TEST.
14 - SECTION 5. MEASUREMENT OF NOISE EMITTED BY SOURCE IN THE TEST ROOM
14 - 5.1 GENERAL.
14 - 5.2 PERIOD OF OBSERVATION.
14 - 5.3 MICROPHONE POSITIONS.
14 - 5.4 NUMBER OF MICROPHONE AND SOURCE POSITIONS.
15 - 5.5 CRITERIA FOR THE PRESENCE OF SPECTRAL IRREGULARITIES.
15 - 5.6 AVERAGING TECHNIQUE WITH MOVING MICROPHONE.
15 - 5.6.1 General.
15 - 5.6.2 Path length for continuous averaging.
15 - 5.6.3 Position of path within test room.
15 - 5.6.4 Speed of traverse.
15 - 5.7 ARRAY OF FIXED MICROPHONES.
15 - 5.8 CORRECTION FOR BACKGROUND SOUND PRESSURE LEVELS.
16 - SECTION 6. CALCULATION OF SOUND POWER LEVELS
16 - 6.1 CALCULATION PROCEDURE FOR THE MEAN BAND PRESSURE LEVELS.
16 - 6.2 DIRECT METHOD FOR DETERMINATION OF SOUND POWER LEVELS.
16 - 6.3 COMPARISON METHOD FOR DETERMINATION OF BAND POWER LEVELS.
17 - SECTION 7. INFORMATION TO BE RECORDED
17 - 7.1 SOUND SOURCE UNDER TEST.
17 - 7.2 ACOUSTIC ENVIRONMENT.
17 - 7.3 INSTRUMENTATION.
17 - 7.4 ACOUSTICAL DATA.
17 - 7.5 INFORMATION TO BE REPORTED.
18 - APPENDIX A - GUIDELINES FOR THE DESIGN OF SPECIAL REVERBERATION TEST ROOMS
18 - A1 GENERAL.
18 - A2 SIZE AND SHAPE OF TEST ROOM.
18 - A3 ABSORPTION OF TEST ROOM.
20 - A4 SOUND ISOLATION.
20 - A5 EXAMPLE OF A PROCEDURE FOR DETERMINATION OF THE NOMINAL REVERBERATION TIME TN OF A ROOM.
22 - APPENIDX B - EXAMPLES OF SUITABLE INSTRUMENTATION SYSTEMS
22 - B1 GENERAL.
22 - B2 RC- SMOOTHING, SOUND LEVEL METER.
22 - B3 ANALOGUE INTEGRATORS.
22 - B4 DIGITAL SYSTEMS.
22 - B5 LEVEL RECORDERS.