30
31
measurements
Noise Dose
What is a Noise Dose?
A noise dose refl ects the accumulated amount of acoustic energy that has entered
your ears over a period of time. It is an important quantity because as more energy
enters your ears, more noise-induced hearing damage may occur. Th
e US and EU
have set limits on the amount of this energy your ears are allowed to absorb each day
while working. For the default settings (EU/NIOSH), the equation governing the
soundBadge noise dose calculation is:
where: (1) pA is the sound pressure (in N/m or equivalently Pascals) measured at time
‘t’ with a microphone processed by an ‘A-weighting’ fi lter, (2) T is the period of time
over which the measurment is accumulated (in hours).
NOTE: When the meter reaches the 9999% display limit, it will display
--.--% and will automatically switch to Pa^2*hrs units.
What are the EU/US Noise Dose Regulations?
Th
e soundBadge can report the ‘noise dose’ as a percentage. Depending on the settings,
100% is the allowable daily dose according to EU or US regulations (EU Directive
2003/10/CE specifi es: criterion = 85 dBA / 8-hr, exchange rate = 3 dB; US regulation
29 CFR 1910.95 specifi es: criterion = 90 dBA / 8-hr, exchange rate=5 dB).
= 100 ∙
( ) ∙
measurements
Noise Dose
Table of actions required according to EU regulations when various noise doses are
exceeded. Equivalent average A-weighted sound levels are given for an 8-hr work day.
Daily Dose
Average A-weighted
Level (8-hr)
Action required according to
regulation
32.0%
80.0 dBA
A risk assessment must be undertaken
including measurements and
employees shall be informed of risks
100.0%
84.9 dBA
Maximum allowable dose before
hearing protection must be supplied
101.2%
85.0 dBA
Hearing protection must be supplied
Hearing protection must be supplied
and a noise control regime to limit
and a noise control regime to limit
exposure adopted
exposure adopted
160.4%
87.0 dBA
Th
ese limits must not be exceeded;
Th
ese limits must not be exceeded;
strategies must implemented to
strategies must implemented to
reduce levels below these limits
reduce levels below these limits
How well does the soundBadge measure Noise Dose?
Th
e soundBadge calcaulates noise dose as a percentage of your daily allowed dose
according to EU/US regulations with a resolution of 1% and with an accuracy that
exceeds allowable standards, typically /- 10%.
