1.1 This specification is for measurement systems used in making sound pressure level measurements in buildings in accordance with ASTM standards and guides. Systems for making sound pressure level measurements in other environments are not addressed in this specification. A future expansion of this specification may include these environments. The systems addressed include one or more microphones and associated components to process the output of the microphone(s) and display the sound pressure level(s). Where the measurement system conforms to a sound level meter specification such as IEC 61672-1:2002, ANSI S1.43, or if time averaged sound levels are not required, ANSI S1.4, it is sufficient to specify the category of precision and accuracy required by the measurement system and that direction is given in the user manual for proper use. Where the system is composed of components, specifications are given for microphone type and orientation, filters and windscreens. Note 1. The category of precision and accuracy is described as class in IEC 61672 and type in ANSI S1.4 and ANSI S1.43. 1.2 The values in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
There is little consistency in the standards written in E33 on the specification of the instruments used for measuring sound pressure levels. This specification is being written to provide a basis for consistency. It is arranged in sections each giving appropriate verbiage for a particular measurement environment. In addition, complex systems are available and being used which are sufficiently accurate and capable of performing measurements typical of ASTM E33 standards, but which are not strictly compliant with normative specifications for sound level meters like IEC 61672. One common example of this is a multi-channel analyzer that can be connected to many types of microphones, but is not designed for a specific microphone type. As a result, the users manual for the multi-channel analyzer cannot give guidance on proper orientation of the microphone in various sound fields. This type of system cannot meet all of the specification in IEC 61672-1 or similar normative specifications. This poses a problem for laboratories which use these complex systems when auditors request verification that their instrumentation complies with the E33 test method which requires compliance with a sound level meter specification.
Keywordssound level meter; measurement system; microphone, free field; random incidence; pressure
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top