AS 4241-1994

1 - AS 4241-1994 ACOUSTICS - INSTRUMENTS FOR THE MEASUREMENT OF SOUND INTENSITY - MEASUREMENT WITH PAIRS OF PRESSURE SENSING MICR
4 - PREFACE
5 - CONTENTS
7 - INTRODUCTION
9 - 1 Scope
9 - 2 Normative references
10 - 3 Definitions
12 - 4 Grades of accuracy
13 - 5 Reference environmental conditions
13 - 6 Sound intensity processors: requirements
16 - 7 Sound intensity probes: requirements
20 - 8 Sound intensity instruments: requirements
20 - 9 Power supplies: requirements
20 - 10 Sound intensity probe calibrators: requirements
21 - 11 Sound intensity processors: performance verification
24 - 12 Sound intensity probes: performance verification
26 - 13 Calibrators: performance verification
27 - 14 Field calibration and checks
28 - 15 Marking and instruction manuals
30 - Annex A - Periodic verification procedures
30 - A1. Processors
30 - A2. Probes
31 - A3. Calibrators
32 - Annex B - Sound intensity processors employing autoranging
33 - Annex C - Sound intensity processors based on DFT analysers converting narrow bands to octave or one-third octave
36 - Annex D - RC networks for generating known phase shifts
37 - Annex E - Dynamic capability index

Specifies the requirements for sound intensity instruments, comprising sound intensity probes and processors which detect sound intensity by pairs of spatially separated pressure sensing microphones. It also specifies requirements for calibrators and the calibration of sound intensity instruments. This Standard is identical with and reproduced from IEC 1043:1993.

The primary purpose of this Standard is to ensure the accuracy of measurements of sound intensity applied to the determination of sound power in accordance with ISO 9614-1. To meet the requirements of that standard, instruments are required to analyse the sound intensity in one-third octave or octave bands, and optionally to provide A-weighted band levels. They are also required to measure sound pressure level in addition to sound intensity level to facilitate the use of the field indicators described in ISO 9614-1.This International Standard only applies to instruments which detect sound intensity by pairs of spatially separated pressure sensing microphones.This International Standard specifies performance requirements for instruments used for the measurement of sound intensity, and their associated calibrators.The requirements are intended to reduce to a practical minimum any differences in equivalent measurements made using different instruments, including instruments comprising probes and processors from different manufacturers.

First published as AS 4241-1994.