Measurement of noise exposure
This Standard describes methods for determining the occupational noise exposure level of workers
(Lex,T) using sampling techniques. Lex,T represents the long-term noise exposure of workers and is
calculated from measurements of Leq,t (3 dB exchange rate) in the workplace.
1) The methods in this Standard are based on established definitions, units, instrumentation, and industry
practice. Noise exposure has been expressed as % dose in the past. However, the Lex,T should be used, as it is
more convenient and less likely to be misunderstood. Refer to Clauses C.1, C.2, and C.4 to convert Lex,T to dose
and vice versa.
2) The methods in this Standard normally form part of any occupational hearing conservation program. Users of
this Standard should be proficient in noise measurement.
This Standard complements other CSA Group and ISO hearing loss prevention standards (see Figure 2),
a) CSA Z1007 for guidance to the person(s) responsible for implementing and managing a hearing loss
prevention program (HLPP);
b) CSA Z94.2 for hearing protection;
c) CSA Z107.6 for audiometric testing for use in hearing loss prevention programs;
d) CSA Z107.58 for noise emission declarations for machinery;
e) CAN/CSA-ISO 5349-1 and CAN/CSA-ISO 5349-2 for hand-transmitted vibration; and
f) ISO 2631 for whole-body vibration.
This Standard provides methods for measuring the occupational noise exposure from all types of noise,
e.g., continuous noise, tonal noise, and impulsive noise. All types of noise (including impulsive noise) are
included in a single equivalent sound level for an individual or group.
Note: Although this Standard was written to measure noise exposure in the workplace, it can equally be used to
measure non-occupational noise exposures, including those from music players, radios, or other sound
This Standard can be used to determine the noise exposure level of individuals (Lex,T) or extended to
groups (LGroup) with similar noise exposures. It can also be used to measure the average noise (Leq,t) from
a given job or activity (e.g., operating a particular machine).
The following subjects are not addressed in this Standard:
a) high energy impulse noise (e.g., such as the noise from nearby gunfire or explosives);
Note: For the purposes of this Standard, high energy impulse noise is any impulse which overloads the
instrumentation, typically 137 dBZ for Class 1 and 130 dBZ for Class 2 sound level meters. To measure such
sounds, an attenuator can be placed between the microphone and pre-amplifier, the pre-amplifier can be set
to be less sensitive (usually by about 10 dB), or a less sensitive microphone can be chosen. However, these
measures are beyond the scope of this Standard. Refer to ANSI/ASA 12.7 and Dancer and Franke (1995).
b) underwater noise measurement, which requires different instrumentation from what is used in air;
Note: More information about underwater noise measurements, but not exposure criteria, can be found in
Robinson et al. (2014).
c) noise level surveys.
Note: Such surveys can be a precursor to noise exposure measurements, but in most cases noise exposure
measurements as described here are more useful and can be commenced directly without a survey. Guidance
on conducting sound level surveys is provided in Annex D.
This Standard provides methods to determine the noise exposure level of workers with a given precision. In certain cases, the user is only interested in determining that a worker’s exposure is above or below the criterion level. Therefore, the methods in this Standard can be less rigorously applied when the noise exposure level is either far above or far below the criterion level.
In this Standard, “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the Standard; “should” is used to express a recommendation or that which is advised but not required; and “may” is used to express an option or that which is permissible within the limits of the Standard.
Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.
Notes to tables and figures are considered part of the table or figure and may be written as requirements.
Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.