Acoustics. Reference zero for the calibration of audiometric equipment - Reference equivalent threshold sound pressure levels for pure tones and supra-aural earphones1 Scope This document specifies a standard reference zero for the scale of hearing threshold level applicable to pure tone air conduction audiometers, to promote agreement and uniformity in the expression of hearing threshold level measurements throughout the world. It states the information in a form suitable for direct application to the calibration of audiometers, that is, in terms of the reference equivalent threshold sound pressure levels of

in the form of plates

A semi-quantitative determination may be carried out using matrix independent standards

tools or solutions to be adopted for its physical implementation in the various target scenarios

adequate facilities

• Pressure strength

It helps the users with guidance and specifications for accessories such as the thermometer pockets for liquid immersed transformers

Retrieval of knowledge from previous projects and common industry sources

Process variables during fabrication

Efficiency

This part of IEC 60749 provides a test method to evaluate the endurance of semiconductor devices used in high temperature and high humidity environments

BS 919-3 and BS 919-4

and zeaxanthin [3]