EN ISO 16032:2024

SLOVENSKI STANDARD
01-julij-2024
Nadomešča:
SIST EN ISO 16032:2005
Akustika - Merjenje ravni zvočnega tlaka obratovalne opreme ali aktivnosti v
stavbah - Inženirska metoda (ISO 16032:2024)
Acoustics - Measurement of sound pressure level from service equipment or activities in
buildings - Engineering method (ISO 16032:2024)
Akustik - Messung des Schalldruckpegels von haustechnischen Anlagen oder Aktivitäten
in Gebäuden - Standardverfahren (ISO 16032:2024)
Acoustique - Mesurage du niveau de pression acoustique des équipements techniques
ou activités dans les bâtiments - Méthode d'expertise (ISO 16032:2024)
Ta slovenski standard je istoveten z: EN ISO 16032:2024
ICS:
17.140.20 Emisija hrupa naprav in Noise emitted by machines
opreme and equipment
91.120.20 Akustika v stavbah. Zvočna Acoustics in building. Sound
izolacija insulation
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 16032
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2024
EUROPÄISCHE NORM
ICS 17.140.20; 91.120.20; 91.140.01 Supersedes EN ISO 16032:2004
English Version
Acoustics - Measurement of sound pressure level from
service equipment or activities in buildings - Engineering
method (ISO 16032:2024)
Acoustique - Mesurage du niveau de pression Akustik - Messung des Schalldruckpegels von
acoustique des équipements techniques ou activités haustechnischen Anlagen oder Aktivitäten in Gebäuden
dans les bâtiments - Méthode d'expertise (ISO - Standardverfahren (ISO 16032:2024)
16032:2024)
This European Standard was approved by CEN on 1 March 2024.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16032:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 16032:2024) has been prepared by Technical Committee ISO/TC 43 "Acoustics"
in collaboration with Technical Committee CEN/TC 126 “Acoustic properties of building elements and
of buildings” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by September 2024, and conflicting national standards
shall be withdrawn at the latest by September 2024.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 16032:2004.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 16032:2024 has been approved by CEN as EN ISO 16032:2024 without any modification.

International
Standard
ISO 16032
Second edition
Acoustics — Measurement of
2024-02
sound pressure level from service
equipment or activities in buildings
— Engineering method
Acoustique — Mesurage du niveau de pression acoustique des
équipements techniques ou activités dans les bâtiments —
Méthode d'expertise
Reference number
ISO 16032:2024(en) © ISO 2024
ISO 16032:2024(en)
© ISO 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 16032:2024(en)
Contents Page
Foreword .iv
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Measurement equipment . 4
5 Test method — General . 4
6 Measurement procedure . 5
6.1 General .5
6.2 Selection of the corner position for the microphone .6
6.3 Selection of the reverberant field positions of the microphone .6
6.4 Measurement of sound pressure levels .6
6.4.1 Measurement of the equivalent continuous sound pressure level .6
6.4.2 Measurement of the maximum sound pressure level .7
6.5 Averaging the sound pressure level .7
6.6 Determination of the background sound pressure level .7
6.7 Standardization or normalization of one–third–octave–band results .7
6.8 Calculation of A- and C-weighted values .8
6.9 Sound sources present in the room (additional measurements) .8
7 Measurement of reverberation time . 8
8 Correction for background noise . 8
9 Precision . 9
10 Test report . 10
Annex A (normative) A-weighting and C-weighting correction values .11
Annex B (normative) Operating conditions and operating cycles for measuring the maximum
sound pressure level and the equivalent continuous sound pressure level .12
Annex C (informative) Form for the expression of results . 19
Bibliography .20

iii
ISO 16032:2024(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 2, Building
acoustics, in collaboration with the European Committee for Standardization (CEN) Technical Committee
CEN/TC 126, Acoustic properties of building elements and of buildings, in accordance with the Agreement on
technical cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 16032:2004), which has been technically
revised.
The main changes are as follows:
— terms and definitions have been revised;
— procedure to detect and average spatial and temporal variations of the sound has been revised;
— measurements can be performed to verify sound levels either from a specific service equipment or an
activity in the building, with operating conditions described in Annex B or by national guidelines if such
exist for a specific type of service equipment, e.g. lifts;
— title is updated to reflect that also sound from activities in the building can be measured according to
this document, e.g. music sound from a restaurant or sports premises in the same building;
— measurements are performed in one–third–octave–bands;
— octave–band levels, without corrections for reverberation times or background noise may be measured
or estimated from the one–third–octave–band levels and reported optionally, but they are not used to
calculate the A-weighted and C-weighted sound pressure levels;
— standardization with respect to reverberation times applies to the 50 Hz to 5 000 Hz one–third–octave–
bands;
— frequency range used to calculate the A-weighted and C-weighted sound pressure levels can include one–
third–octave bands from 25 Hz to 10 000 Hz but shall always include the bands 50 Hz to 5 000 Hz;
— Annex C added providing an example form for the expression of results.

iv
ISO 16032:2024(en)
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
ISO 16032:2024(en)
Introduction
Many countries have building regulations intended to protect people from noise in their homes or
workplaces. For the purpose of verification of compliance with such regulations, there is a need for a
standardized method for the measurement of sound pressure levels from service equipment or activities
in this building. This document specifies a procedure for such measurements, under specific operating
conditions and operating cycles.

vi
International Standard ISO 16032:2024(en)
Acoustics — Measurement of sound pressure level from
service equipment or activities in buildings — Engineering
method
1 Scope
This document specifies an engineering method for the measurement of sound pressure levels in rooms
from service equipment installed in the building.
This document covers specifically measurements of sound from sanitary installations, mechanical
ventilation, heating and cooling service equipment, lifts, rubbish chutes, heating devices, blowers, pumps and
other auxiliary service equipment, and motor driven car park doors. It can also be applied to measurements
of sounds from other types of equipment or activities within the building, e.g. noise from sport facilities or
restaurants.
The measurement of noise from external sound sources generating air-borne or ground-borne noise in the
building are not included in this document.
The methods are suitable for rooms with volumes of approximately 300 m or less for instance, in dwellings,
hotels, schools, offices and hospitals.
The methods are not intended for measurements in large auditoria or concert halls.
2 Normative references
The following documents are referred to in the text in such a way that some or all their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 3382-2, Acoustics — Measurement of room acoustic parameters — Part 2: Reverberation time in ordinary
rooms
IEC 60942, Electroacoustics — Sound calibrators
IEC 61260-1, Electroacoustics — Octave-band and fractional-octave-band filters
IEC 61672-1, Electroacoustics — Sound level meters - Part 1: Specifications
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/

ISO 16032:2024(en)
3.1
sound pressure level
L
i
ten times the logarithm to the base 10 of the ratio of the square of the sound pressure p (t), to the square of
the reference sound pressure p , measured in a position i with a particular time weighting and a particular
frequency weighting, selected from those defined in IEC 61672-1
Note 1 to entry: L is expressed in decibels.
i
Note 2 to entry: The reference sound pressure is 20 μPa.
3.2
maximum sound pressure level with time weighting "S"
L
Smax
maximum sound pressure level measured in one–third–octave–bands determined with time weighting “S”
3.3
maximum sound pressure level with time weighting "F"
L
Fmax
maximum sound pressure level measured in one–third–octave–bands determined with time weighting “F”
3.4
equivalent continuous sound pressure level
L
eq
sound pressure level measured in one–third–octave–bands determined as a time average of the squared
sound pressure during a stated integration time
Note 1 to entry: The integration time, can be indicated with additional subscripts for the stated time interval or a
stated duration, e.g. L or L or L .
22-06 30s 1h
3.5
average sound pressure level
L
ten times the logarithm to the base 10 of the ratio of the space and time average of the square of the sound
2 2
pressure p (t), to the square of the reference sound pressure p , the space average being taken over the
entire room with the exception of those parts where the direct radiation of a sound source or the near field
of the boundaries (walls, etc.) is of significant influence
Note 1 to entry: L is expressed in decibels.
Note 2 to entry: The space average can be calculated from measurements of the sound pressure level L taken in n
i
positions, including repetitions in one position, according to the Formula:
1 n
 01, L 
i
L =10 lg 10 dB
∑
 
i=1
n
 
Note 3 to entry: The measured sound pressure levels can be maximum time weighted levels L or L , or
Smax Fmax
equivalent continuous sound pressure levels L .
eq
3.6
reverberation time
T
duration required for the space-averaged sound energy density in an enclosure to decrease by 60 dB after
the source emission has stopped
Note 1 to entry: The reverberation time is expressed in seconds.
Note 2 to entry: T can be evaluated based on a smaller dynamic range than 60 dB and extrapolated to a decay time of
60 dB. It is then labelled accordingly. Thus, if T is derived from the time at which the decay curve first reaches 5 dB
and 25 dB below the initial level, it is labelled T . If decay values of 5 dB and 35 dB below the initial level are used, it
is labelled T .
ISO 16032:2024(en)
Note 3 to entry: T is measured in one–third–octave–bands from 50 Hz to 5 000 Hz.
3.7
standardized average sound pressure level
L
nT
average sound pressure level standardized to a reference reverberation time in one–third–octave–bands.
Note 1 to entry: To calculate the standardized quantity, the following formula applies:
 
T
LL= − 10lg dB
nT  
T
 0 
where
T is the measured reverberation time in seconds;
T reference reverberation time 0,5 seconds.
3.8
normalized average sound pressure level
L
n
average sound pressure level normalized to an equivalent sound absorption area of 10 m in one–third–
octave–bands.
Note 1 to entry: To calculate the normalized quantity, the following formula applies:
AT
 
LL= − 10lg dB
n
 
01, 6 V
 
where
A is the reference equivalent sound absorption area in square meters; A = 10 m ;
0 0
T is the measured reverberation time in seconds;
V is the room volume in cubic meters;
0,16 has the unit (s/m).
3.9
A- weighted average sound pressure level
L
A
m
01, ()LA+
 
kk
L =10 lg 10 dB
A
∑
 k=1 
 
where
L is the average sound pressure level in each one–third–octave–band k;
k
A is the A-weighting correction of the one–third–octave–band k according to Annex A.
k
3.10
C- weighted average sound pressure level
L
C
m
01, ()LC+
 
kk
L =10 lg 10 dB
C ∑
 k=1 
 
ISO 16032:2024(en)
where
L is the average sound pressure level in each one–third–octave–band k;
k
C is the C-weighting correction of the one–third–octave–band k according to Annex A.
k
4 Measurement equipment
Measurement of sound pressure levels according to this document shall be made with a one–third–octave–
band analyser that registers all sound pressure levels simultaneously.
The instrumentation system, including the microphone and cable, shall meet the requirements for a class
1 instrument specified in IEC 61672-1. The one–third–octave–band filters shall meet the requirements for
class 1 filters specified in IEC 61260-1.
The residual noise of the used instrumentation shall be assessed, to be compared with the background levels
according to Clause 8.
At the beginning and at the end of the measurements, the sensitivity of the instrumentation shall be verified
with a sound calibrator class 1 according to IEC 60942. If the calibration measurement deviates from
previous calibrations by more than 0,5 dB, do not use this equipment until the reason for this deviation has
been clarified and appropriate actions have been taken to ensure a correct sensitivity within its dynamic
range and frequency range.
It is recommended the microphone is mounted on a stable stand, e.g. a tripod, with an adjustable height.
NOTE The stand can be equipped with a resilient mount for the microphone to reduce background noise from
vibrations of the floor.
5 Test method — General
The sound pressure level, L , from a service equipment or an activity in a building shall be measured in
i
a fixed position i as the linear (unweighted) spectrum in one–third–octave–bands during a specified time
period or operating cycle of the service equipment under test.
For the evaluation of a maximum sound pressure level with a time weighting “S” or “F”, register the one–
third–octave–band sound pressure levels at that time when the maximum A-weighted or C-weighted sound
pressure level indicated by the instrument occurs in this microphone position.
The equivalent continuous sound pressure level, L , shall be determined with an integration time
eq
determined according to the guidelines in Annex B, unless there are guidelines in national requirements and
regulations which shall then be applied instead of the guidelines in Annex B.
The sound pressure levels taken in different positions are then used to calculate the average sound pressure
levels in one–third–octave–bands.
These average sound pressure levels shall be corrected for background noise measured according to 6.6.
The background noise corrected average sound pressure levels in one–third–octave–bands shall be used to
calculate the standardized average sound pressure levels or the normalized average sound pressure levels,
unless national requirements only require uncorrected levels to be reported.
Finally, the A-weighted average sound pressure level and C-weighted average sound pressure level are
calculated from the background noise corrected and standardized or normalized or uncorrected one–third–
octave–band results.
The average sound pressure levels which can be reported according to this document are given in Table 1.

ISO 16032:2024(en)
Table 1 — A- and C-weighted average sound pressure levels
A-weighted average sound C-weighted average sound pressure
pressure level level
(calculated from one–third octave band (calculated from one–third octave
sound pressure levels) band sound pressure levels)
L L
ASmax CSmax
Maximum sound pressure level
L L
ASmax,nT CSmax,nT
with time weighting “S”
L L
ASmax,n CSmax,n
L L
AFmax CFmax
Maximum sound pressure level
L L
AFmax,nT CFmax,nT
with time weighting “F”
L L
AFmax,n CFmax,n
L L
Aeq Ceq
Equivalent continuous sound
L L
Aeq,nT Ceq,nT
pressure level “eq”
L L
Aeq,n Ceq,n
The different weighted average sound pressure levels given in Table 1 are not comparable. Only measurement
results obtained with the same time and frequency weightings shall be compared. When measurement
results are compared with legal requirements it shall be ensured that both refer to the same quantity. Thus,
the notation in Table 1 shall be used when reporting measurement results.
Octave–bands sound pressure levels, directly measured or estimated from the one–third–octave–band
results, can be presented optionally, without correction for background noise and without standardization
or normalization.
6 Measurement procedure
6.1 General
The sound pressure level shall be determined for a specified operating condition and operating cycle of a
service equipment or a given time frame for an activity in the same building.
NOTE 1 Sounds in a room from external sources of noise can be measured according to ISO 1996–2.
NOTE 2 Background sounds in large spaces or in rooms with highly sound absorbing surfaces, e.g. an office
landscape, can be measured according to ISO 3382–3.
Operating conditions and operating cycles are determined according to Clause 5.
Special care shall be taken to ensure that operating conditions of automated service equipment are fulfilled,
either by supervised operation of the source or by some kind of additional measurement of the source itself,
e.g. with an accelerometer.
Windows and doors shall be closed during the measurements, but air inlets shall be in their normal position.
It is recommended the operator performing the test stays outside the room during the measurement to
ensure the background noise is unaffected by the operator. A microphone stand can then be used according
to Clause 4.
NOTE 3 It is often efficient to listen to the microphone signal in headphones to ensure no background sound affects
the measurement, or to record and playback this signal after the measurement. See Clause 8.
NOTE 4 In some situations, it can be advantageous that the operator is present in the room to listen for intermittent
background noise.
If one or several persons are present in the room during the measurements, this measurement condition
shall be stated in the test report.
If the sound contains clearly audible tonal components or time variations, this shall be stated in the test
report.
ISO 16032:2024(en)
According to this document, sound pressure levels are first measured in three microphone positions, one
position in a selected corner of the room and two positions in the reverberant sound field. The measurements
are repeated in the selected corner and two or four new room positions in case the results differ from each
other by more than limits according to 6.4.
The sound pressure level is measured and corrected according to 6.2 to 6.9.
6.2 Selection of the corner position for the microphone
To select the corner position (number 1), search for the corner of the room with the highest C-weighted
equivalent continuous sound pressure level. Use the chosen operating condition and operating cycle or any
stable condition suitable for the finding of the location with the highest sound level.
For the selection of the corner position, the C-weighted equivalent continuous sound pressure level can be
measured directly e.g. by the use of an integrating sound level meter. Hence, calculation from one–third–
octave–bands and corrections for reverberation times or background noise shall not be applied for this
purpose. The selection procedure for the corner position stated above shall be used prior to all measurements
according to this document.
The corner microphone position shall, preferably, be located at each corner 0,5 m from the walls and the
floor. If this position is not feasible due to protruding furniture, obstacles etc., increase the height to 1,0 m or
if necessary to 1,5 m above the floor.
The microphone position shall be at least 0,2 m away from any obstacle. Move away small protruding items
close to the microphone that do not affect the sound field, if necessary. If the sound pressure level in a corner
is dominated by direct sound from a source in the room – e.g. a ventilation outlet – this corner shall be left
out when choosing the corner position.
6.3 Selection of the reverberant field positions of the microphone
Choose two additional positions (number 2 and 3) somewhere in the reverberant field of the room. Whenever
practical, the minimum distance between each of the positions 1 (the corner position), 2 and 3 shall
preferably be 1,5 m but at least 1,0 m. The distance to any sound source in the room shall be at least 1,5 m.
The distance between positions 2 and 3 and any room surface shall be at least 0,50 m. In small rooms where
one or several positions cannot fulfil this requirement, the distance to a room surface may be decreased to
0,30 m. The height above floor level shall be at least 0,5 m and not more than 2,0 m. The microphone shall be
placed at different heights as well as moved to different positions on the floor.
6.4 Measurement of sound pressure levels
6.4.1 Measurement of the equivalent continuous sound pressure level
Carry out the measurements of the equivalent continuous sound pressure level in positions 1, 2 and 3 during
the chosen operating conditions and operating cycles according to 6.1.
If the difference between the highest and the lowest A-weighted equivalent continuous sound pressure levels
at these three measurement positions, as indicated directly by the instrument without any corrections
for reverberation times nor background noise, is equal to or less than 3,0 dB, then proceed to carry out
corrections and calculations according to 6.5 to 6.7.
If the difference exceeds 3,0 dB, carry out additional measurements with the microphone at the same corner
position and at two new room positions (number 4 and 5), observing the distances described in 6.3. If the
difference between the highest and the lowest of the six A-weighted equivalent continuous sound pressure
levels, without any corrections, is less than 6,0 dB, then carry out corrections and calculations according to
6.5 to 6.7.
If the difference exceeds 6,0 dB, carry out additional measurements at the same corner microphone position
and a two new room positions (number 6 and 7), observing the distances described in 6.3. If the difference

ISO 16032:2024(en)
between the highest and the lowest of the nine A-weighted sound pressure levels is less than 9,0 dB, then
carry out corrections and calculations according to 6.5 to 6.7.
If the difference is larger than 9,0 dB and the three readings in the corner position indicate the sound source
is not stable, then the measurement session shall be interrupted and the reasons for the large differences
should be investigated before a new series of measurement are carried out. No data from the interrupted
series of measurement shall be used to calculate weighted single number values.
If a statistical estimate of the time variation of the sound shall be derived (optionally), this can be done in
addition to the ordinary measurements. Take a new sequence of corner measurements and calculate the
standard deviation, based on the squared sound pressures. It can then be assumed this standard deviation
is representative also for the average sound pressure level in the room.
6.4.2 Measurement of the maximum sound pressure level
If the maximum sound pressure levels are measured, use the highest C-weighted maximum sound pressure
level in each position with a similar procedure to 6.4.1 to determine the number of measurements to be
made and to calculate the average sound pressure level. However, in the case of sound events of short
duration, an equivalent sound pressure level measured during a fixed integration time that comprises each
sound event can be used instead of the maximum sound pressure level to determine the required number of
measurements.
The chosen operating conditions and operating cycles shall be used.
NOTE The measurement uncertainty can be high when maximum sound pressure levels are measured in the
lower one–third–octave–bands because of time delays caused by the sound level meter filtering circuits and hence the
level can depend on the equipment.
6.5 Averaging the sound pressure level
Calculate for each one–third–octave–band the average sound pressure level of all the measurements made
according to 6.4.1 or 6.4.2 with the chosen time and frequency weightings respectively. The levels shall be
rounded to one decimal place.
NOTE Maximum sound pressure levels with time weightings "S" or "F" are determined as time and spatial
averages of measurements in several positions. This procedure is considered necessary to reach an acceptable
reproducibility. Since the averaging is made from several squared sound pressure signals, it follows that the highest
sound pressure levels will to some extent determine the averaged maximum sound pressure level. This average will
be close to the highest level registered in any of the positions chosen, but not identical to this. Hence, it can be useful to
explain this specific meaning of an average maximum sound pressure level in the test report.
6.6 Determination of the background sound pressure level
The background sound pressure level shall be determined in one–third–octave–bands as the equivalent
continuous sound pressure levels over a period of approximately 30 s just before or after each set of
measurements. The same microphone positions shall be used as for the service equipment sound pressure
level measurements. Corrections for background sounds are applied according to Clause 8.
6.7 Standardization or normalization of one–third–octave–band results
The one–third–octave–band results corrected for background noise shall be standardized or normalized
to reference absorption properties of the room, unless uncorrected values are requested in a national
regulation or guideline that refers to measurements according to this document.
Measure the reverberation time according to Clause 7 and make the standardization by use of formula in 3.7,
or the normalization according to the formula in 3.8.
Because of severe problems with determining reverberation times in the 25 Hz, 31,5 Hz, 40 Hz, 6 300 Hz,
8 000 Hz and 10 000 Hz one–third–octave–bands, the measured sound pressure levels in these bands shall

ISO 16032:2024(en)
not be standardized nor normalized. If any of these bands contribute to the A- or C-weighted sound pressure
level, this shall be mentioned in the test report.
NOTE Standardization or normalization based on measured reverberation times may lead to a bias error in
rooms without sound diffusing objects in case one or several surfaces are highly sound absorbing, e.g. a room with
an acoustical ceiling. This error is caused by late and rather weak reflections between acoustically reflecting parallel
surfaces, e.g. the walls, that result in a prolonged reverberation time. However, the sound pressure level can still be
reduced by absorption of the early and strong reflections from the absorbing surface. Hence, the correction based on
reverberation times may then be overestimated. In this kind of room, it may be useful to compare the earliest part of
the reverberation decay with the late part in the evaluation of the reverberation time, e.g. comparing a T value with
a a T value. If the difference is notable, this can be mentioned in the test report.
6.8 Calculation of A- and C-weighted values
Determine the A-weighted level from the one–third–octave–band levels according to the formula in 3.7 with
frequency weights given in Annex A, either within a restricted frequency range 50 Hz to 5 000 Hz or within
an extended range 25 Hz to 10 000 Hz. For the extended frequency range, the measured sound pressure
levels in the 25 Hz, 31,5 Hz, 40 Hz, 6 300 Hz, 8 000 Hz and 10 000 Hz one–third–octave–bands are included
with 0 dB correction terms for the reverberation times according to 6.7. Indicate the frequency range applied
in the test report.
Determine the C-weighted level from the one–third–octave–band levels according to the formula in 3.10
with frequency weights given in Annex A within the extended frequency range 25 Hz to 10 000 Hz.
The A-weighted and C-weighted results shall be rounded to integer numbers.
NOTE It can be useful to compare the calculated A– and C–weighted results corrected for background noise with
the values indicated directly by the instrument. If the difference is more than 2 dB, the calculations can be checked for
possible explanations.
6.9 Sound sources present in the room (additional measurements)
In situations where sound sources are present in the room – e.g. a ventilation outlet in the wall or in the
ceiling – a separate measurement position shall be used for each source. For noise sources in the wall a
position is chosen 1 m in front of the source and 1,5 m above floor level. For a noise source in the ceiling,
the position shall be 1,5 m above floor level, directly below the source. Additional measurement result(s)
shall not be standardized or normalized. They shall be reported separately and shall not be included in the
average of the levels measured in microphone positions according to 6.4.
7 Measurement of reverberation time
The reverberation time shall be measured in the 50 Hz to 5 000 Hz one–third–octave–bands–according to
ISO 3382-2, preferably using the impulse response method at least in the lower one–third–octave–bands
50 Hz to 315 Hz.
8 Correction for background noise
This method is only suitable provided that the background noise is approximately constant in time. If
the background noise level is 10 dB or more below the sound pressure level of the service equipment, no
correction shall be made.
The residual noise of the used instrumentation shall be compared to the measured background noise levels.
If the residual noise has had an influence on the background levels, this shall be stated in the test report.
If the background noise level is 4 dB to 10 dB below the sound pressure level of the service equipment, the
measured sound pressure level shall be corrected using the following Formulae (1) to (3):
L = L – K (1)
ISO 16032:2024(en)
()−01, ΔL
 
K =−10 lg 11− 0 (2)
 
Δ LL=−  L (3)
where
L is the corrected sound pressure level, in decibels;
L is the measured one–third–octave–band sound pressure level from the service equipment including
background noise, in decibels;
L is the one–third–octave–band background sound pressure level, in decibels;
K is the one–third–octave–band correction value, in decibels.
A difference of 4 dB corresponds to a correction value of 2,2 dB. If the difference is less than 4 dB the
correction value shall be limited to 2,2 dB, and in the test report, it shall be stated that the measurement
result is influenced by background noise. For comparison with noise limits, the measuring result can be
considered as the upper limit of the service equipment sound pressure level. It shall be stated whether the
background noise is influencing the A-weighted and C-weighted average sound pressure levels.
NOTE 1 If the background noise is varying with time – e.g. caused by road traffic – a reliable correction cannot
be made. However, the maximum sound pressure levels of the background noise can be determined over a period
of 10 min to 15 min in the corner microphone position. If the maximum level is 10 dB or more below the service
equipment sound pressure level the result can be regarded valid without correction. It can also be helpful to monitor
the time signal to select the appropriate time slot for measurements and check the validity in all relevant one–third–
octave–bands.
NOTE 2 A simple check on–site is to compare the maximum level to the equivalent level in the middle of the
frequency range during one or several measurement period. For many stable sources this difference can be in the
order of 5 dB. If this difference is maintained during the remaining measurements, it is likely that these measurements
have not been disturbed by background sounds from closing doors, footfall noise etc.
9 Precision
Table 2 shows estimates of the standard deviation associated with reproducibility of average sound pressure
levels. The values are estimated based on a limited number of measurements on sound sources constant in
[3]
time . Fluctuations of the sound pressure level of the source will increase the measurement uncertainty,
particularly for maximum sound pressure levels.
Table 2 — Estimated standard deviation of average levels, associated with reproducibility
One–third–octave–band Octave–band Standard deviation of
centre frequencies centre frequencies reproducibility
Hz Hz dB
25, 31,5 and 40 31,5 1,9
50, 63 and 80 63 1,9
100, 125 and 160 125 1,9
200, 250 and 315 250 1,5
400, 500 and 630 500 1,2
800 to 10 000 1 000 to 8 000 1,0
a
0,8
A-weighted
a
C-weighted
1,2
a
Valid for a consta
...