NF EN 457 : 1992

Cooperating organizations
National foreword
Foreword
Specification
0 Introduction
1 Scope
2 Normative references
3 Definitions
4 Symbols
5 Safety requirements
6 Test methods
7 Calculation of effective masked threshold
8 Guidelines for the design of auditory danger
     signals
Tables
A.1 Calculation of the level of the masked threshold
     for a given octave spectrum
B.1 Mean attenuation data of a hearing protector
     according to ISO 4869-1
Figures
B.1 Graph displaying the octave band analysis of the
     ambient noise, the masked threshold and of the
     auditory danger signal during the 'on' period
B.2 Graph displaying octave band analysis of the
     ambient noise equal to the masked threshold and of
     the auditory danger signal
B.3 Graph displaying octave band analysis of the basic
     traffic and crane noise, the masked threshold and
     of the auditory danger signal
B.4 Graph displaying octave band analysis of ambient
     noise equal to the masked threshold and of the
     auditory danger signal
B.5 Graph displaying octave band analysis of the
     ambient noise, the masked threshold and of the
     auditory danger signal
B.6 Graph displaying the octave band analysis of the
     ambient noise, the masked threshold and the
     auditory danger signal (above) and the effective
     levels under the hearing protector (below)
Annexes
A (informative) Example for the calculation of the
     effective masked threshold according to clause 7
B (informative) Examples of warning signals
National appendices
NA (informative)
NB (informative)

Gives the safety and ergonomic requirements and the corresponding test methods for auditory danger signals. Does not apply to verbal danger warnings. Special regulations such as those for a public disaster and public transport are not affected. Covers normative references, definitions, symbols, safety requirements, test methods, calculation of effective masked threshold and guide-lines for the design of auditory danger signals. Contains tables and figures.