Czech Metrology Institute  
Okružní 31, 638 00 Brno  
 
 
 1. ------IND- 2018 0336 CZ - EN- ------ 20180803 --- --- PROJET 
Executive summary for the EC (not part of this legislation)  
Personal sound exposure meters are placed on the market and put into use in the Czech Republic 
pursuant to Act  No 505/1990 on metrolo gy, as amended.  
The subject of this notified regulation is to lay down metrological and technical requirements for 
these measuring instruments.  This regulation also stipulates tests for type approval and verification.  
(End of executive summary.)  
 
 
Contact  person:  Mgr.Tomáš 
Hendrych  
Phone:545  555 414 
 
P U B L I C  D E C R E E  
 
As the authority with substantive and territorial jurisdiction for stipulating metrological and technical 
requirements for specified measuring instruments and stipulating test methods for type a pproval and 
verification of legally specified instruments pursuant to §  14(1) of Act  No 505/1990, on metrology, as 
amended (hereinafter the ‘Metrology Act ’), and in accordance with the provisions of §  172 et seq. of 
Act No 500/2004, the Code of Administrat ive Procedure (hereinafter the ‘CAP’), the Czech Metrology 
Institute (hereinafter the ‘CMI’) commenced ex officio proceedings on 2  March  2016 pursuant to §  46 
of the CAP, and, based on supporting documents, issues the following:  
 
 
I. 
D R A F T  G E N E R A L  M E A S U R E 
Ref.:0111 -OOP -C059 -16 
 
laying down the metrological and technical requirements for legally controlled measuring 
instruments, including testing methods for type approval and verification of the following legally 
controlled measuring instruments:  
'personal s ound exposure meters'  
 Measure of a General Nature No  0111 -OOP -C059 -16 
2 1 Basic definitions  
For the purposes of this general measure, terms and definitions pursuant to VIM and VIML1 and the 
following terms and definitions will apply:  
1.1 
sound exposure  
the time integral of the square of the instantaneous  value of sound pressure  A for a stipulated event, 
for example a workday  
NOTE  Sound exposure (weighted by frequency function A) is expressed symbolically as:  
dttp Et
tA)(2
12
 (1) 
where pA2(t) is the square of the instantaneous value of sound pressure  A as a function of time t for an integration 
period from t1 to t2. 
The unit of sound exposure E is the pascal squared hour if the acoustic pressure pA is in pascals and time t is in 
hours.  
1.2 
personal sound exposure meter  
a device (measuring instrument) for measuring sound exposure, frequency -weighted by the function 
A, caused by continuous, intermittent, variable, irregular  or pulse sounds; the sound exposure value is 
usually given in pascal squared hours  
1.3 
equivalent sound pressure level  A 
10 times th e decimal logarithm of the ration of the time -averaged square of the acoustic pressure, 
frequency -weighted by the function A during the averaging period T to the square of the standard 
reference acoustic pressure, expressed in decibels  
NOTE The equivalent acoustic pressure level  A LAeqT is symbolically given by:  



2
002
, / )( /1 log10 pdttp T LT
A TAeq
 (2) 
where time t and the averaging period T are expressed in the same units, pA(t) is the instantaneous value of sound 
pressure A in  pascals, and p0 is a reference sound press ure of twenty micropascals (20  μPa), i.e. 20·10-6 Pa. 
The equivalent sound pressure level  A, over the averaging period T, applies to the total sound exposure occurring 
during this time according to the relationship  
TAeqLTpE, ·1,0 2
010··
 (3) 
where E is sou nd exposure in pascal squared hours, p0 is the reference acoustic pressure of twenty micropascals, 
i.e. 20·10-6 Pa, and T is the averaging period in hours.  
                                                      
1 TNI 01 0115 International Vocabulary of Metrology —Basic and General Concepts and Associated Terms 
(VIM) and International Vocabulary of Legal Metrology (VIML) are part of the technical harmonisation 
compendium ‘Terminology in the field of metrology ’, which is publicly available at www.unmz.cz.  Measure of a General Nature No  0111 -OOP -C059 -16 
3 1.4 
normalised 8  h average sound pressure level  A 
the time -averaged square of acoustic pressure leve l A during the normalised period Tn = 8 h is such 
that the sound exposure is the same as the sound exposure for variable sound in a location where the 
overall sound exposure occurs for a time that is not necessarily 8  h, expressed in decibels  
1.5 Ranges  
1.5.1 
range of acoustic pressure levels  A 
the lower and upper, time -averaged, levels of acoustic pressure  A determined without exponential time 
weighting, stipulated by the manufacturer, between which linear amplitude requirements, expressed in 
decibels, are  fulfilled pursuant to this Measure  
1.5.2  
sound exposure range  
the range between the upper and lower sound exposure, both of which must be stipulated by the 
manufacturer, within which the requirements of this Measure are met and which are displayed on the 
sound exposure indicator  
1.6 References  
1.6.1  
reference direction  
the direction of sound incidence stipulated by the manufacturer to determine absolute acoustic 
sensitivity and frequency characteristics  
1.6.2  
reference frequency  
a frequency of 1  kHz for de termination of absolute acoustic sensitivity  
1.6.3  
reference acoustic pressure level  
the acoustic pressure level stipulated by the manufacturer for determining the absolute acoustic 
sensitivity  
1.6.4  
reference integration period  
the integration period stip ulated by the manufacturer for determining the absolute acoustic sensitivity  
1.6.5  
reference sound exposure  
calculated sound exposure corresponding to the acoustic pressure level at the reference frequency, 
applicable to the reference integration period  
1.7 Microphone  
1.7.1  
electret microphone  
a microphone in which an electromagnetic field is induced by an internal permanent charge on one of 
the capacitor electrodes  Measure of a General Nature No  0111 -OOP -C059 -16 
4 1.7.2  
condenser microphone  
a microphone whose operation is based on changes in electrical ca pacity  
1.7.3  
piezoelectric microphone  
a microphone whose operation is based on the piezoelectric properties of a material  
2 Metrological requirements  
Metrological requirements are based on the requirements of international standards.  
Measuring instrument t ypes approved pursuant to the Metrology Act shall be subject to the 
metrological requirements applicable at the time they were put into circulation.  
Unless specified otherwise, metrological requirements apply to ranges stipulated by the manufacturer 
if the se are broader than the specified ranges, and to reference conditions.  
2.1 Rated operating conditions  
Sound exposure indicated in response to the reference acoustic pressure level at a frequency of 1  kHz 
for the reference integration period cannot change b y more than -11 % to +12  % for changes:  
 within ±10  % of the reference pressure; or  
 over a temperature range of at least  0 °C to 40 °C; or  
 a relative humidity range of at least 30  % to 90  %. 
Reference operating conditions are as follows:  
 atmospheric pressur e 101.3  kPa; 
 air temperature 20  °C; 
 relative air humidity 65  %; and  
 absence of any significant interference.  
2.2 Measuring interval  
The indicated sound exposure must be at least from 0.1  Pa2h to 99.9  Pa2h and the smallest sound 
exposure increment 0.1  Pa2h.If the lower acoustic pressure limit is less than 80  dB, the lower limit of 
the sound exposure range must be less than 0.1  Pa2h. 
The frequency range must be 63  Hz to 8  kHz, with 31.5  Hz to 12.5  kHz recommended.  
The acoustic pressure level range must be at least 80  dB to 130  dB. 
2.3 Maximum permissible error  
At the reference frequency of 1  kHz, under reference ambient conditions  and for successive planar 
sound waves propagating toward the microphone in the reference direction, the indicated sound 
exposure mu st be in the range -21 % to +26  % of the reference sound exposure.  
2.4 Frequency weighting  
A complete personal sound exposure meter must have a relative frequency characteristic  A. For each 
specific octave band frequency over a minimum range of 63  Hz to 8  kHz, the ratio of the measured 
sound exposure to the sound exposure at 1  kHz must meet sound exposure tolerances.  Permissible 
values for the 'max sound exposure ratio' and 'min sound exposure ratio' are determined by the 
following formula (1):  
 ε +∆ε= 100.1(A + ∆A) (4) Measure of a General Nature No  0111 -OOP -C059 -16 
5 where:  ε  .........   the value of the sound exposure ratio according to the relationship ε = 100.1A, 
 Δε ........   the value of the sound exposure tolerance applicable to the given specific octave band 
nominal frequency;  
 A  .........   the value of the weighting function  A in dB for the given octave band nominal 
frequency;  
 ΔA .......  the value of the tolerance (positive and negative) for the weighting function  A in dB 
applied to the corresponding value of the weighting function  A. 
For intermediate frequencies, broader tolerance  limits are used, determined from the tolerances for the 
values of the weighting function  A for the two corresponding nominal adjacent octave band 
frequencies.  
2.5 Amplitude linearity of the response to steady signals  
For steady sinusoid signals with frequ encies of 63  Hz, 1  kHz, and 8  kHz, and for changes in both the 
input acoustic pressure level and the integration duration, the indicated sound exposure must be within 
the range of -21 % to +26  % of the calculated sound exposure.  
2.6 Response to signals of short duration  
For a proposed resultant sound exposure value of 1  Pa2h, the value shown by the personal sound 
exposure meter in response to a sequence of repeating tone pulses with a frequency of 4  kHz must 
meet tolerances for a corresponding sound exposur e indicated in response to a steady reference signal 
at a frequency of 4  kHz with a nominal acoustic pressure level  A of 95  dB. 
The duration of individual pulses must be:  
 1 ms, with a 999  ms interval between individual pulses;  
 10 ms, with a 990 or 9  990 ms interval between individual tone pulses.  
The sound exposure indicated for a sequence of these tone pulses must be:  
 within -21 % to +26  % of the sound exposure indicated for a steady reference signal for levels 
with tone pulses up to 125  dB; and  
 within -29 % to +41  % of the sound exposure indicated for a steady reference signal for levels 
with tone pulses up to the upper limit of the stipulated acoustic pressure level range.  
2.7 Response to unipolar pulses  
For identical nominal integration durations, the in dicated sound exposure in response to a sequence of 
positive unipolar pulses must be within –21 % to +26  % of the sound exposure indicated in response to 
a sequence of negative pulses of identical amplitude, duration  and periodicity.  
2.8 Microphone  
The met rological properties of a microphone must be such that a complete sound exposure meter 
meets stipulated metrological requirements as a whole.  
2.9 User calibration  
The user must have means at their disposal to check and maintain the sensitivity of the perso nal sound 
exposure meter.  If this means using an acoustic calibrator, it must be of a suitable type and be 
calibrated by a test laboratory.  
3 Technical requirements  
Technical requirements are based on the requirements of international standards.  Measure of a General Nature No  0111 -OOP -C059 -16 
6 Measuring instrument types approved prior to the entry into force of this regulation shall be subject to 
the technical requirements applicable at the time they were put into circulation.  
3.1 In general  
A personal sound exposure meter is a combination of a microphone , an amplifier with the requisite 
frequency weighting function  A, an apparatus to square frequency -weighted acoustic pressure signal, a 
time integrator, a sound exposure indicator  and an automatically blocking overload indicator.  
A signal processor may be used to provide the functionality of an amplifier with the requisite 
frequency weighting function  A, a squaring device  and a time integrator.  The sound exposure indicator 
can be replaced by a separable display unit or computer with the respective software.  A personal 
sound exposure meter may optionally be equipped with a data transmission interface.  
Sound exposures accumulated during the measurement period must be stored in memory until the 
device is zeroed, and must not be deleted by the automatically bloc king overload indicator.  
A complete personal sound exposure meter may consist of one or more parts.  An exposure meter or 
part thereof used to measure and record data that is worn must be small and light.  The microphone 
cable and similar items must have an appropriate length so that the microphone can be attached to the 
individual, a helmet, etc.  
The manufacturer must provide a means of replacing the input electrical signal in the location of the 
microphone (by a test access point, an input adapter, etc.) fo r purposes of testing an otherwise 
complete personal sound exposure meter without its microphone.  An output test point is also 
recommended.  
The maximum acoustic pressure level in the location of the microphone and the maximum peak -to-
peak voltage that can be connected to the electrical input without damaging the personal sound 
exposure meter must be stipulated in the user manual or in another suitable manner.  
If the manufacturer recommends or assumes the use of a multi -frequency calibrator, its type must be  
specified in the user manual or in another suitable manner, as must be information for obtaining 
accurate responses during tests to verify the operation of the personal sound exposure meter.  
3.2 Microphone  
The microphone may be built based on various desi gn principles, for example a condenser 
microphone, an electret microphone, etc.  
It is recommended that the diameter of the microphone is 13.20  mm or 7.00  mm and that condenser 
microphones be equipped with a removable protective grille.  If the microphone do es not have the 
dimension specified above, the manufacturer must supply an adapter so that it will have this 
dimension.  
3.3 Sound exposure indicator  
The indicator primarily displays sound exposure, either directly or as a fraction or percentage of a 
sound exposure specified by the manufacturer.  
Acoustic pressure levels that exceed the upper limit of the stipulated acoustic pressure level range 
must be indicated by an automatically blocking overload indicator.  
3.4 Power supply  
The type of power supply recomm ended by the manufacturer must ensure that this measuring 
instrument operates properly for at least 8  hours and in any temperature within a range specified by the 
manufacturer of the personal sound exposure meter.  When batteries are used, the manufacturer must 
ensure that sufficient battery voltage is checked.  Measure of a General Nature No  0111 -OOP -C059 -16 
7 3.5 Software  
Software must be identifiable and must be secured from accidental or intentional damage.  
3.6 Data transmission  
A personal sound exposure meter or a certain part thereof may be equipped wi th interfaces permitting 
connection of additional devices.  If these interfaces are used, the measuring instrument's hardware and 
software must continue to operate properly and it must be impossible to influence its metrological 
properties.  
3.7 Protection a gainst unauthorised tampering  
The measured data and measurement results must be protected from unauthorised tampering either 
physically, via software  or another secure method.  
4 Labelling the measuring instrument  
4.1 Markings on the measuring instrument  
Every part of a personal sound exposure meter, if feasible, must bear the following information:  
a) manufacturer identification;  
b) type designation;  
c) the serial number;  
d) a marking indicating that it complies with the requirements of a technical standard upon which 
the metrological and technical requirements of this Measure of a General Nature are based.  
The reference number of the standard and its year of issue are indicated.  If this information 
cannot be indicated on the measuring instrument, it must at least be st ated in the technical 
documentation, in information about the measuring instrument shown on the indicator 
(display), etc.;  
e) the CE mark.  If for any reason the CE mark cannot be placed on the measuring instrument, it 
must at least be shown in the technical d ocumentation or on the package;  
f) the name of the displayed quantity (sound exposure) and its units.  This information may be 
shown on the indicator, or the user manual must describe how to determine sound exposure.  
All marks and labels must be legible, perma nent, unambiguous  and indelible by ordinary means.  
4.2 Official mark placement  
A personal sound exposure meter must have a suitable place for the main official mark, which must be 
visible.  
4.3 Information provided by the manufacturer  
4.3.1 User manual  
With  every measuring instrument, the manufacturer must supply a user manual that must contain at 
least all necessary instructions and information for proper configuration (adjustment), use, testing, and 
verification of the personal sound exposure meter, includ ing: 
 If not specified in separate documentation, information on the microphone used and the 
applicability of a multi -frequency calibrator, if the manufacturer assumes this possibility.  
 The user manual should specify a suitable type of multi -frequency acous tic calibrator or 
electrostatic calibrator that could be used for acoustic tests of the frequency weighting 
function  A of a complete personal sound exposure meter.  For the same purpose, if needed, 
relevant numerical correction values must be available, and  if needed an adapter (inserted 
part) stipulated by the manufacturer of the personal sound exposure meter or the microphone Measure of a General Nature No  0111 -OOP -C059 -16 
8 manufacturer, which will correctly make up for any difference in the diameter of the 
microphone and the opening for inserting the mi crophone into the calibrator chamber, as well 
as suitable and properly delimiting the functional chamber of the calibrator.  
 The maximum acoustic pressure level in the location of the microphone and the maximum 
peak -to-peak voltage that can be connected to the electrical input without damaging the 
personal sound exposure meter must be stipulated in the user manual.  
4.3.2 The manufacturer's declaration of conformity  
The technical documentation supplied with a personal sound exposure meter must include a 
decla ration of conformity or otherwise formulated but clear and reliable information from the 
manufacturer concerning compliance with electromagnetic and electrostatic compatibility 
requirements.  This declaration may be a separate document, part of the user man ual, or be contained in 
other technical information about the product.  The document must contain information concerning 
compliance with relevant standards.  
5 Type approval of the measuring instrument  
These measuring instruments are not subject to type appr oval pursuant to the Metrology Act.  
6 Initial verification  
6.1 In general  
During initial verification of personal sound exposure meters, the following are performed after a 
check of submitted technical documentation (not necessary if the test laboratory is  already familiar 
with this exposure meter type):  
a) a visual inspection;  
b) acoustic tests in the laboratory or in an acoustic chamber;  
c) electrical tests in the laboratory.  
6.2 Visual inspection  
The following is assessed during a visual inspection:  
a) markings and labels;  
b) that the measuring instrument is complete pursuant to prescribed technical documentation;  
c) that the measuring instrument or its individual parts are not damaged, and that it is functional;  
d) that the software matches accompanying technical documentati on. 
6.3 Test equipment requirements  
The following measuring instruments and equipment are used for testing:  
a) a multi -frequency acoustic calibrator;  
b) a sine wave generator;  
c) a shaping generator;  
d) a voltage meter;  
e) a frequency meter;  
f) an amplifier;  
g) a speaker;  
h) a standard reference sound meter;  
i) an acoustic calibrator;  
j) a timepiece;  Measure of a General Nature No  0111 -OOP -C059 -16 
9 k) a printer;  
l) a PC;  
m) equipment specified in the user manual for connecting electrical signals equivalent to signals 
from the microphone.  If required by the test laboratory, this equipment must be submitted 
together with the personal sound exposure meter being submitted for testing.  
6.4 Measuring instruments tests  
The manufacturer may recommend equivalent tests as alternatives to the tests described below.  
If a reading increment of the personal s ound exposure meter is smaller than the minimum stipulated 
resolution of 0.1  Pa2h, test durations shorter than those specified below for basic versions of tests may 
be used.  
All tests should be performed under reference conditions, or be related to them.  If this requirement 
cannot be met, initial and subsequent verification tests can be performed under the following ambient 
conditions: atmospheric pressure 80  kPa to105  kPa, air temperature 20  °C to 26  °C and relative 
humidity 25  % to 70  %. 
The personal soun d exposure meter must be checked and configured, if necessary, in accordance with 
information from the manufacturer.  In accordance with Articles  2.3 and 2.9, a check is performed and 
the instrument's absolute sensitivity is set if needed.  
If the operation of the personal sound exposure meter is to be tested using acoustic signals, the 
personal sound exposure meter must be installed according to the manufacturer's recommendations 
and tested using the recommended type of test equipment and sound field.  If ele ctrical input signals 
are provided using input test equipment (input point, microphone equivalent, input adapter, or an 
equivalent device provided by the manufacturer), the microphone's acoustic properties are tested using 
a different suitable procedure (f or example a test using a multi -frequency calibrator or in an acoustic 
chamber, etc.).  Equivalence between the level of the input electrical signal and the level of the 
acoustic signal is proven using calibration.  
6.5 Acoustic tests of the complete measuri ng instrument (with microphone)  
The following measurements and tests are performed:  
a) frequency weighting function  A; 
b) internally generated noise.  
6.5.1 Test of the frequency weighting function  A 
A test using a multi -frequency calibrator, if feasible.  This is  a test of the frequency weighting 
function  A by measuring relative sound exposure at octave band nominal frequencies within a 
minimum range of 63  Hz to 8  kHz.  If this test cannot be performed acoustically, it is performed using 
electrical signals (see bel ow) and a simplified acoustic test of the frequency weighting function  A is 
performed.  
NOTE  If during this test, while using a multi -frequency acoustic calibrator, the acoustic pressure level 
requirement cannot be met, the acoustic pressure level generated  by the multi -frequency acoustic calibrator can 
be set at a value as close as possible to the required one, but in any case no less than 110  dB. In this case it is 
recommended that such a test be supplemented with electrical tests pursuant to Article  6.6.2  at 63  Hz, 1  kHz, and 
8 kHz.  
The provisions of this article can also be applied to acoustic tests that can be performed in another 
manner, depending on the test laboratory's facilities, for example in an acoustic chamber, etc.  
6.5.2 Test of internally gene rated noise  
Internally generated noise is measured with the microphone attached.  The personal sound exposure 
meter is set to the most sensitive measurement range, if it has multiple measurement ranges.  The Measure of a General Nature No  0111 -OOP -C059 -16 
10 acoustic pressure level  A of ambient sound in the microphone location must be sufficiently less than 
the measured level of internally generated noise.  The indicated equivalent acoustic pressure level  A is 
recorded (or the sound exposure indication, which is converted to the equivalent level for the 
averag ing period), averaged for 30  seconds or longer, if so stipulated in the user manual, etc.  
NOTE  In the case of an exposure meter with one measurement range that covers only the minimum stipulated 
measurement range, the internally generated noise level must be below the measurement range.  
6.6 Electrical tests (with a microphone replacement, etc.)  
The microphone is replaced by the microphone adapter, or the test input point is used.  The following 
measurements and tests are performed:  
a) amplitude linearity of the  response to steady signals;  
b) if it was not possible to perform a test of the frequency weighting function  A by measuring 
relative sound exposure acoustically, a test using an electrical signal is performed in a similar 
manner;  
c) response to signals of short duration;  
d) response to unipolar pulses;  
e) automatically blocking overload indicator.  
6.6.1 Test of the amplitude linearity of the response to steady signals  
6.6.1.1 Test of the amplitude linearity of the response to steady signals, basic version  
The amplitude  linearity of the response to steady signals of 1  kHz must be tested for various 
combinations of signal levels and integration periods of up to 8  hours.  Amplitude linearity must be 
measured for exposure values from approximately triple the lower limit of t he exposure range to 
approximately 80  % of the upper limit of the sound exposure range and at sound exposure intervals 
that are no greater than a five -fold increase or decrease in sound exposure.  
Using equation (3) sound exposure is calculated, which shoul d be indicated for the measured level of 
the respective input signal and the measured integration period.  For all combinations, the indicated 
sound exposure should match the calculated sound exposure and should be within the limits of 
maximum permissible e rror pursuant to Article  2.3. 
At 63  Hz and 8  kHz the amplitude linearity of the response to steady signals can be tested over a more 
limited range  
6.6.1.2 Test of the amplitude linearity of the response to steady signals, basic version  
In a number of cases , a limited version of the amplitude linearity test of the response to steady signals 
is sufficient if the smallest sound exposure increment is 0.01  Pa2h and the lower sound exposure range 
limit is 0.01  Pa2h or very close to this value. During testing usin g a 1  kHz input signal, it is then 
sufficient for at least one test to be performed for a one -hour integration period, and other tests can be 
shorter to a reasonable degree.  
Even in the case of a shorter test, tolerances of -21 % and +26  % apply to all ind icated exposures.  
6.6.2 Test of the frequency weighting function  
The frequency weighting function is tested using sine wave signals of constant amplitude.  The 
acoustic pressure level of the 1  kHz input signal must be approximately 3  dB below the upper limi t of 
the stipulated acoustic pressure range.  
Tests must be performed at eight nominal octave band frequencies, from 63  Hz to 8  kHz.  The signal 
duration must be chosen so that the indicated sound exposure is greater than 20x the sound exposure 
resolution.  
For individual stipulated frequencies, the sound exposure ratio is determined, which is the measured 
sound exposure at some frequency divided by the measured exposure at 1  kHz.  At all test frequencies Measure of a General Nature No  0111 -OOP -C059 -16 
11 the measured sound exposure ratios must match correspond ing proposed sound exposure ratio results 
and must meet tolerances stipulated as per Article  2.4. 
6.6.3 Test of response to signals of short duration  
The response of a personal sound exposure meter to signals of short duration is determined by 
comparing th e sound exposure indicated in response to a sequence of repeating tone pulses with a 
frequency of 4  kHz and a duration of 1  ms or 10  ms to the sound exposure, E4k, indicated in response 
to a reference steady signal at a frequency of 4  kHz.  
Measured sound e xposure, E4k, is the sound exposure indicated by the tested instrument in response to 
a steady sine wave of a frequency of 4  kHz and an equivalent input sound pressure level of 94.0  dB 
(i.e. sound pressure level  A of 95  dB) for 47  minutes and 26  seconds, i n order to elicit a rated sound 
exposure of 1  Pa2h with tolerance from 0.71  Pa2h to 1.41  Pa2h. In justified cases, a different guideline 
rated sound exposure can be chosen for purposes of this test.  
The input signal level, the duration between tone pulses,  and the overall sound exposure period for a 
series of tone pulses must be selected to give a rated sound exposure of 1  Pa2h, or a modified guideline 
rated sound exposure (see above).  The acoustic pressure level of 4  kHz sine signals from which tone 
pulses  are derived must have a range of at least 114.0  dB to 129.0  dB or greater, i.e. up to the upper 
acoustic pressure limit.  
In order to prove compliance with requirements for response to signals of short duration, any suitable 
combination of tone pulses with  a frequency of 4  kHz, a duration of 1  ms or 10  ms, and a fill factor of 
1:100 and 1:1  000. The sound exposure indicated for a sequence of these tone pulses must comply 
with the tolerance stipulated pursuant to Article  2.6. 
6.6.4 Test of response to unipol ar pulses  
The test of response to unipolar pulses uses a series of rectangular pulses.  The same integration period 
must be chosen for both positive and negative pulses; it is usually such that a sequence of positive 
pulses elicits an indicated sound exposu re greater than 10  Pa2h. In justified cases a different value may 
be chosen.  The indicated sound exposure in response to a sequence of positive pulses must match the 
sound exposure indicated in response to negative impulses, within tolerances pursuant to A rticle  2.7. 
6.6.5 Test of the automatically blocking overload indicator  
A suitable test signal for testing the response of the automatically blocking overload indicator is a 
single tone pulse comprising a sequence of four 1  kHz sine wave periods.  The overl oad indicator must 
switch on and remain blocked when the test signal reaches a level where the equivalent acoustic 
pressure level  A elicited by a steady signal of a frequency of 1  kHz from which the tone pulses were 
derived reaches a level 3  dB greater tha n the upper limit of the stipulated acoustic pressure level range.  
The overload indicator must not switch on if this equivalent level is equal to the upper acoustic 
pressure limit.  In justified cases, a different procedure many be used.  
6.7 Microphone test s 
Separate tests of a personal sound exposure meter microphone are usually not performed.  Usually a 
microphone is tested using a test of the acoustic weighted frequency function  A of the complete sound 
exposure meter using a multi -frequency calibrator purs uant to Article  6.5.1 or a different test of the 
acoustic weighted frequency function  A. If the test shows that the complete personal sound exposure 
meter complies with stipulated requirements, this is simultaneously considered proof that the 
microphone is  capable of functioning properly.  
7 Subsequent verification  
Tests pursuant to Chapter  6 are performed during subsequent verification of the personal sound 
exposure meter.  Measure of a General Nature No  0111 -OOP -C059 -16 
12 8 Notified standards  
To specify metrological and technical requirements for measuring  devices and to specify verification 
and type -approval test methods stemming from this Measure of a General Nature, the CMI notifies 
Czech technical standards, other technical standards or technical documents of international or foreign 
organisations or ot her technical documents containing detailed technical requirements (hereinafter 
‘notified standards ’). The CMI shall publish a list of these notified standards attached to the relevant 
measures, together with the general measure, in a manner accessible to the public (on www.cmi.cz ). 
Compliance with notified standards or parts thereof is considered, to the extent and under the 
conditions stipulated by a general measure, to be compliance with the requirements stipulated by th is 
measure to which these standards or parts thereof apply.  
Compliance with notified standards is one way of demonstrating compliance with the requirements.  
These requirements may also be met by using another technical solution guaranteeing an equivalent o r 
higher level of protection of legitimate interests.  
 
II. 
G R O U N D S  
Pursuant to §  14(1)(j) of the Metrology Act, the CMI has issued this Measure of a General Nature 
toward the implementation of §  6(2), §  9(1) and (9), and  § 11a(3) of the Metrology Act, layi ng down 
metrological and technical requirements for specified measuring instruments and tests for type 
approval and verification of specified measuring instruments —personal sound exposure meters.  
Decree No  345/2002 stipulating measuring instruments for man datory verification and measuring 
instruments subject to type approval, as amended, classifies this type of measuring instrument as a 
measuring instrument subject to verification under item  6.1.5 in the Annex ’s 'List of Specified 
Measuring Device Types'.  
This legislation (General Measure) will be notified in accordance with Directive (EU)  2015/1535 of 
the European Parliament and of the Council of 9  September  2015 laying down a procedure for the 
provision of information in the field of technical regulations and of rules on Information Society 
services.  
 
III. 
I N S T R U C T I O N S  
In accordance with §  172(l), in conjunction with §  39(l) CAP, the CMI has stipulated a time limit for 
comments of 30  days as of the date of posting on the official notice board.  Comments subm itted after 
this time limit will not be considered.  
The persons concerned are hereby invited to comment on this draft Measure of a General Nature.  With 
a view to the provisions of §  172(4) CAP, the comments shall be submitted in writing.  
In accordance with  § 174(l) CAP in conjunction with §  37(l) CAP, it must be clear who is making the 
comments, which measure of a general nature they concern, how it contradicts legislation or how the 
measure of a general nature is inaccurate, and they must be signed by the person making them.  
The supporting documents for this draft General Measure may be consulted at the Czech Metrology 
Institute, Legal Metrology Department, Okružní 31, 638 00 Brno, after making arrangements by 
telephone.  
This general measure shall be posted  for 15  days.  
 Measure of a General Nature No  0111 -OOP -C059 -16 
13  
 
 
 
 ...………………………… ..............  
RN Dr Pavel Klenovský  
Director -General  
 
Person responsible for accuracy:  Mgr.  Tomáš Hendrych  
Posted on:  
Signature of the authorised person confirming posting:................................................. ... 
Removed on:..............................  
Signature of the authorised person confirming removal:....................................................