ISO 5982:2019

INTERNATIONAL ISO
STANDARD 5982
Third edition
2019-03
Mechanical vibration and shock —
Range of idealized values to
characterize human biodynamic
response under whole-body vibration
Vibrations et chocs mécaniques — Enveloppes de valeurs probables
caractérisant la réponse biodynamique d'individus soumis à des
vibrations globales du corps
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Definition of values of apparent mass of the human body under vibration .3
4.1 Apparent mass of the seated body under x-axis vibration . 3
4.2 Applicability of values of apparent mass of the seated body under x-axis vibration. 3
4.3 Apparent mass of the seated body under y-axis vibration . 7
4.4 Applicability of values of apparent mass of the seated body under y-axis vibration . 8
4.5 Apparent mass of the seated body under z-axis vibration .11
4.6 Applicability of values of apparent mass of the seated body under z-axis vibration .12
4.7 Apparent mass of the standing body under z-axis vibration .15
4.8 Applicability of values of apparent mass of the standing body under z-axis vibration .16
5 Seat-to-head transmissibility of the seated human body under vertical vibration .17
5.1 Definition of values of seat-to-head transmissibility .17
5.2 Applicability of values of seat-to-head transmissibility .18
Annex A (informative) Identification of the data used to define the range of idealized
apparent mass and seat-to-head transmissibility .20
Annex B (informative) Lumped mass model .28
Annex C (informative) Mathematical models .31
Annex D (informative) Apparent mass of seated body under vertical vibration for three
different ranges of body masses (55 kg, 75 kg and 98 kg) .40
Bibliography .42
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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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 documents 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).
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.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 108, Mechanical vibration, shock and
condition monitoring, Subcommittee SC 4, Human exposure to mechanical vibration and shock.
This third edition cancels and replaces the second edition (ISO 5982:2001), which has been technically
revised. The main changes compared to the previous edition are as follows:
— Previously given ranges of idealized values for the apparent mass of the seated human body have
been updated.
— The range of idealized values is now defined for seated individuals, with and without a back
support, exposed to sinusoidal or broad-band random vibration in the x-axis, y-axis and z-axis with
unweighted RMS acceleration lower or equal to 2 m/s .
— Idealized values of apparent mass for standing individuals, while exposed to vertical vibration
(z-axis), have been added.
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.
iv © ISO 2019 – All rights reserved

Introduction
The biodynamic response of the seated human body subjected to vibration has widely been assessed
in terms of driving-point mechanical impedance or apparent mass and seat-to-head transmissibility.
While the first two functions relate to the force and motion at the point of input of vibration to the
body (“to the body” transfer functions), the last function refers specifically to the transmission of
motion through the body (“through the body” transfer function). Since biodynamic responses are non-
linear with respect to vibration magnitude, those functions are defined for a specific range of vibration
magnitudes. Knowledge of these functions under conditions representative of those encountered
while driving specific types of vehicles can find applications in current laboratory procedures defined
for assessing vehicle seat performance and for predicting whole-body vibration exposure levels on
platforms of mobile machinery. Although such procedures currently require that specific tests be
conducted with human subjects acting as test loads, these functions can form the basis for developing
a mechanical system capable of simulating the human body or for deriving functions that can account
for the human interface when the tests are being conducted with rigid masses. Such functions can
further form the basis for developing analytical models representing the human body, which through
combination with suitable suspension seat models can provide numerical means of estimating the
seat performance and of achieving optimal seat suspension and cushion design. Notwithstanding the
above applications, this document provides unification of available published data on the driving-point
mechanical impedance, apparent mass and seat-to-head transmissibility response functions satisfying
a specific set of conditions. In view of the restrictions imposed on posture and vibration excitation
levels, the values defined for each of these functions can be more applicable to drivers of off-road, heavy
road and industrial vehicles.
The response of the human body subjected to whole-body vibration is dependent on several factors,
including
a) subject mass,
b) posture and back support,
c) feet support and
d) excitation amplitude.
In this document, the apparent mass and the seat-to-head transmissibility are employed to describe the
biodynamic response characteristics of the human body to forced translational motion of the buttocks
or feet, as a function of frequency.
The unexplained differences between the mean modulus and phase values of apparent mass and
seat-to-head transmissibility reported in studies conducted independently, under a similar range of
experimental conditions, has dictated the form in which the standardized values for these functions is
presented. A synthesis of measured values has been performed using data published in the literature.
The most probable range of values of apparent mass and seat-to-head transmissibility modulus and
phase are defined as a function of frequency by upper and lower limit envelope curves, which encompass
the mean values of all data sets, at each frequency. The smoothened envelopes have been constructed
from successive piecewise approximations using a fixed number of points while creating an overlap. The
mean of the accepted data sets, weighted according to the number of subjects involved, and standard
deviation computed with respect to the weighted mean, are defined as a function of frequency, and
represent the target values for all applications of this document. Any data that fall within the range of
idealized values defined by upper and lower limit envelope curves can be considered to be an acceptable
representation of the biodynamic response functions of the human body under the specific conditions
defined.
No modulus or phase presented as a function of frequency in this document corresponds precisely
to the mean value measured in a single investigation involving human subjects at all frequencies.
Furthermore, measured data for a single subject can appear out of range of the upper and lower limit
envelope curves.
Major changes to previously given ranges of idealized values for the apparent mass of the seated human
body were considered necessary in view of the new data available since the publication of the second
edition (ISO 5982:2001). The second edition only considered the driving-point mechanical impedance/
apparent mass of seated individuals, without a back support, exposed to vertical vibration (z-axis). As
part of this document, a range of idealized values is defined for seated individuals, with and without a
back support, exposed to sinusoidal or broad-band random vibration in the x-axis, y-axis and z-axis with
unweighted RMS acceleration lower or equal to 2 m/s . Idealized values of apparent mass for standing
individuals, while exposed to vertical vibration (z-axis), have also been added. Values for seat-to-head
transmissibility (STHT) remained mostly unchanged and are still provided for seated individuals
without a back support while exposed to z-axis vertical vibration.
This document incorporates the most recent data to have been published on the apparent mass and seat-
to-head transmissibility, while satisfying the conditions specified above. Annex A provides information
on the selection of published data to define the range of idealized values of apparent mass and seat-to-
head transmissibility. The frequency ranges for defining these values are limited to 0,5 Hz to 20 Hz for
vertical vibration (z-axis) and to 0,5 Hz to 10 Hz for lateral (y-axis) and fore-aft (x-axis) vibration, since
predominant vibrations are known to occur within those ranges for several types of off-road, heavy
road and industrial vehicles. In Annex B, an analytical model of the seated human body is provided to
satisfy the range of idealized values defined for the apparent mass and seat-to-head transmissibility
functions. Alternatively, mathematical expressions in the form of transfer functions are provided in
Annex C to approximate the mean (target) values defined for these functions. Finally, values for the
apparent mass are provided in Annex D for three specific body masses ranges on the basis of a study
involving 27 male subjects.
vi © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 5982:2019(E)
Mechanical vibration and shock — Range of idealized
values to characterize human biodynamic response under
whole-body vibration
1 Scope
This document describes the range of idealized values of the apparent mass modulus and phase
applicable to seated individuals with and without a back support subjected to x-, y- and z-axis sinusoidal
or broad-band random vibration and to standing individuals subjected to z-axis sinusoidal or broad-
band random vibration under specific experimental conditions. Additionally, this document describes
the range of idealized values of seat-to-head transmissibility modulus and phase applicable to seated
individuals without a back support subjected to z-axis sinusoidal or broad-band random vibration.
The ranges of idealized values defined in this document are considered to be valid for subjects on a
rigid seat (or standing on a rigid platform for z-axis only), with feet supported and vibrated. The range
of idealized seat-to-head transmissibility values is considered to be applicable also to the condition with
the feet hanging freely. For seated individuals subjected to sinusoidal or broad-band random vibration,
the apparent mass values are defined over the frequency range of 0,5 Hz to 10 Hz for the x-axis and
y-axis, and over the frequency range of 0,5 Hz to 20 Hz for the z-axis. The frequency and amplitude
characteristics of the vibration fall within the range for which most vibration exposure is likely to
predominate while driving vehicles such as agricultural tractors, earth-moving machinery and fork-lift
trucks. Application to automobiles is not covered by this document in view of the lack of a meaningful
database for conditions involving posture and vibration excitation levels most likely associated with
car driving.
The upper and lower values of modulus and phase defined at each frequency for each of the biodynamic
response functions considered represent the range of most probable or idealized values. The middle
values represent overall weighted means of the human data and define the target values for general
applications. Such applications can involve the development of mechanical analogues for laboratory seat
testing, or of functions to correct for the human interface when representing the body as a rigid mass,
or the development of analytical human body models to be used for whole-body vibration exposure
estimations or for seat and cushion design optimization.
2 Normative references
The following documents are referred to in the text in such a way that some or all of 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 5805, Mechanical vibration and shock — Human exposure — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5805 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
apparent mass
M( f )
complex ratio of applied periodic excitation force at frequency f, F( f ), to the resulting vibration
acceleration at that frequency, a( f ), measured at the same point and in the same direction as the applied
force, as given by Formula (1)
Ff
()
Mf = (1)
()
af
()
Note 1 to entry: The apparent mass is a complex quantity (i.e. it possesses real and imaginary parts) from which
the modulus and phase can be computed.
Note 2 to entry: This document is based on measurements in which both force and acceleration were measured
at the same point, this being the point of introduction of vibration to the body, namely the buttocks (seat-body
interface) or the feet.
Note 3 to entry: In the case of non-harmonic vibration, apparent mass is determined from the force and
acceleration spectra.
3.2
driving-point mechanical impedance
z( f )
complex ratio of applied periodic excitation force at frequency f, F( f ), to the resulting vibration velocity
at that frequency, v( f ), measured at the same point and in the same direction as the applied force, as
given by Formula (2)
Ff
()
zf = =j2πfM f (2)
() ()
vf
()
where
M( f ) is the apparent mass;
j represents the complex phasor between the mechanical impedance and apparent mass
j=−1 .
()
Note 1 to entry: The relationship between driving-point mechanical impedance and apparent mass is entirely
determined by the fixed relationship between velocity and acceleration for which a 90° phase difference exists
under periodic excitation.
Note 2 to entry: In the case of non-harmonic vibration, driving-point mechanical impedance is determined from
the force and velocity spectra.
3.3
seat-to-head transmissibility
complex non-dimensional ratio of the response motion of the head to the forced vibration motion at the
buttocks (seat-body interface)
Note 1 to entry: The ratio can be one of displacements, velocities or accelerations.
Note 2 to entry: The seat-to-head transmissibility is a complex quantity (i.e. it possesses real and imaginary
parts) from which the non-dimensional modulus and the phase can be computed.
Note 3 to entry: In the case of non-harmonic vibration, seat-to-head transmissibility is determined from the
motion spectra.
2 © ISO 2019 – All rights reserved

4 Definition of values of apparent mass of the human body under vibration
4.1 Apparent mass of the seated body under x-axis vibration
The modulus and phase of the apparent mass of the seated body with and without a back support are
given in Tables 1 and 2, respectively, and (for illustration) in Figures 1 and 2 as a function of frequency,
for the x-axis direction of excitation. According to the definitions, the modulus is given in terms of
kilograms for apparent mass. The table and diagram contain three values of modulus and phase at each
frequency. Numerical values are quoted up to four significant figures for the purpose of calculation,
and do not reflect the precision of knowledge of the apparent mass. Linear interpolation is permitted to
obtain values at frequencies other than those listed in Tables 1 and 2 at one-third-octave band centre
frequencies.
The upper and lower limiting values at each one-third-octave band centre frequency encompass the
mean values of all data sets selected, and are shown by continuous curves in Figures 1 and 2. The
central value at each frequency, shown by dashed curves in Figures 1 and 2, provides an estimate of the
weighted mean of all data sets selected, and forms the target value for all applications. The standard
deviations computed with respect to the weighted mean (target) values are also listed in Tables 1 and 2.
Applications shall generate/employ values of apparent mass between the upper and lower limits given
in Tables 1 and 2 at any frequency, and represent “to the body” transfer functions applicable to the
seated human body under the conditions specified and over the frequency range of 0,5 Hz to 10 Hz.
If an application only satisfies the requirements of this document at certain frequencies, then those
frequencies should be stated in any description of the application.
4.2 Applicability of values of apparent mass of the seated body under x-axis vibration
The values of apparent mass are applicable to the seated human body, subjected to sinusoidal or broad-
band random fore-aft vibration, while seated on a rigid surface with the feet resting flat on the base
platform and the back being supported and unsupported. The limits of applicability approximately
correspond to the range of measurement conditions over which data were obtained, as follows:
a) the posture is described as erect seated with or without backrest support, while the feet are
supported and vibrated;
b) the angle for the back support is ranging from 90° to 102° for the condition with a backrest support;
c) the mass of the subjects ranges from 57 kg to 92 kg for the condition with a backrest support, and
from 55 kg to 103,6 kg for the condition without a backrest support;
2 2
d) the RMS amplitude of unweighted sine and random excitation is between 0,4 m/s and 1,0 m/s
within the frequency range of 0,5 Hz to 10 Hz.

Table 1 — Modulus and phase of the mean (target) and range of idealized apparent mass of the
seated body with a back support under x-axis vibration
Modulus Phase
Frequency
kg °
Hz
Upper Lower Standard Upper Lower Standard
Mean Mean
limit limit deviation limit limit deviation
0,5 65,3 68,8 62,8 2,4 −0,1 1,8 −2,8 1,9
0,63 65,6 68,5 63,8 1,8 −0,3 1,2 −2,7 1,6
0,8 68,2 70,0 66,7 1,2 −1,2 −0,9 −1,8 0,4
1 69,5 72,1 67,8 1,7 −1,8 −1,2 −2,4 0,5
1,25 71,5 74,9 68,9 2,3 −4,7 −3,8 −5,9 0,8
1,6 74,8 78,3 71,1 2,7 −8,2 −7,3 −9,4 0,9
2 78,7 83,4 73,8 3,8 −12,2 −10,3 −14,6 1,9
2,5 85,2 92,5 79,3 5,3 −20,1 −15,0 −24,7 4,5
3,15 87,5 92,5 82,8 3,9 −31,4 −24,0 −38,4 6,6
4 86,4 90,8 78,9 4,9 −49,2 −40,6 −60,7 8,5
5 76,1 83,8 60,1 9,4 −69,7 −58,5 −80,8 8,9
6,3 56,7 67,3 47,8 7,4 −87,1 −77,4 −101,3 9,7
8 39,4 47,8 33,3 6,8 −100,6 −90,7 −115,2 9,5
10 28,4 35,3 23,6 5,6 −107,6 −100,3 −122,2 8,9

4 © ISO 2019 – All rights reserved

Key
X frequency in Hz
Y1 modulus in kg
Y2 phase in °
NOTE For an explanation of the curves, see 4.1.
Figure 1 — Mean (target) and range of idealized values for the apparent mass of the seated body
with a back support under x-axis vibration

Table 2 — Modulus and phase of the mean (target) and range of idealized apparent mass of the
seated body without a back support under x-axis vibration
Modulus Phase
Frequency
kg °
Hz
Upper Lower Standard Upper Lower Standard
Mean Mean
limit limit deviation limit limit deviation
0,5 62,9 70,3 48,6 8,2 −12,8 1,4 −20,1 9,8
0,63 63,6 71,0 48,5 8,7 −13,6 1,2 −21,6 10,3
0,8 61,7 68,2 48,5 7,1 −19,7 −1,0 −34,0 14,2
1 58,5 66,9 46,8 7,0 −25,3 −1,2 −40,1 17,4
1,25 49,5 62,7 40,2 8,5 −28,7 −4,3 −45,5 16,7
1,6 46,3 58,5 39,1 6,4 −33,5 −9,3 −48,4 14,0
2 48,7 60,1 41,8 6,8 −39,3 −14,6 −50,1 13,0
2,5 47,9 59,4 38,8 7,3 −54,9 −24,6 −72,9 16,9
3,15 40,3 51,5 28,6 6,9 −71,1 −33,7 −97,5 21,1
4 31,4 45,3 19,1 8,4 −87,5 −49,3 −113,8 22,1
5 23,8 36,3 13,6 8,0 −105,6 −71,6 −124,8 19,2
6,3 14,5 21,2 8,5 4,3 −122,6 −92,0 −137,9 16,8
8 8,2 12,0 5,4 2,3 −129,1 −103,7 −145,5 15,1
10 5,7 7,5 3,6 1,3 −130,2 −108,6 −147,2 14,3

6 © ISO 2019 – All rights reserved

Key
X frequency in Hz
Y1 modulus in kg
Y2 phase in °
NOTE For an explanation of the curves, see 4.1.
Figure 2 — Mean (target) and range of idealized values for the apparent mass of the seated body
without a back support under x-axis vibration
4.3 Apparent mass of the seated body under y-axis vibration
The modulus and phase of the apparent mass of the seated body with and without a back support are
given in Tables 3 and 4, respectively, and (for illustration) in Figures 3 and 4 as a function of frequency,
for the y-axis direction of excitation. According to the definitions, the modulus is given in terms of
kilograms for apparent mass. The table and diagram contain three values of modulus and phase at each
frequency. Numerical values are quoted up to four significant figures for the purpose of calculation,
and do not reflect the precision of knowledge of the apparent mass. Linear interpolation is permitted to
obtain values at frequencies other than those listed in Tables 3 and 4 at one-third-octave band centre
frequencies.
See 4.1 for more details.
4.4 Applicability of values of apparent mass of the seated body under y-axis vibration
The values of apparent mass are applicable to the seated human body, subjected to sinusoidal or broad-
band random lateral vibration, while seated on a rigid surface with the feet resting flat on the base
platform and the back being supported and unsupported. The limits of applicability approximately
correspond to the range of measurement conditions over which data were obtained, and are identical to
those described in 4.2.
Table 3 — Modulus and phase of the mean (target) and range of idealized apparent mass of the
seated body with a back support under y-axis vibration
Modulus Phase
Frequency
kg °
Hz
Upper Lower Standard Upper Lower Standard
Mean Mean
limit limit deviation limit limit deviation
0,5 65,3 72,9 59,7 5,3 −19,8 −9,8 −26,7 6,5
0,63 65,6 74,0 59,8 5,8 −19,6 −10,6 −25,7 5,7
0,8 67,8 77,0 63,0 5,7 −23,4 −17,1 −28,1 4,2
1 70,6 79,1 64,6 5,6 −29,7 −22,8 −34,8 4,7
1,25 70,9 82,7 63,0 7,4 −39,7 −33,8 −44,8 4,7
1,6 67,1 83,3 55,2 11,7 −56,9 −52,8 −61,5 3,9
2 58,9 80,1 46,4 13,5 −71,5 −66,6 −79,4 5,0
2,5 43,3 52,0 36,0 6,4 −80,7 −73,0 −92,1 7,1
3,15 30,5 34,4 26,2 3,2 −86,9 −77,5 −98,7 8,0
4 21,7 26,5 16,7 3,3 −91,4 −85,3 −101,1 6,6
5 17,3 21,7 11,5 3,6 −95,3 −88,4 −101,9 5,6
6,3 13,4 17,6 7,7 3,6 −103,1 −96,0 −110,0 5,6
8 9,2 12,8 4,1 3,2 −109,5 −104,4 −113,6 3,7
10 6,5 9,1 1,8 2,7 −110,7 −104,5 −114,3 3,9

8 © ISO 2019 – All rights reserved

Key
X frequency in Hz
Y1 modulus in kg
Y2 phase in °
NOTE For an explanation of the curves, see 4.1.
Figure 3 — Mean (target) and range of idealized values for the apparent mass of the seated body
with a back support under y-axis vibration

Table 4 — Modulus and phase of the mean (target) and range of idealized apparent mass of the
seated body without a back support under y-axis vibration
Modulus Phase
Frequency
kg °
Hz
Upper Lower Standard Upper Lower Standard
Mean Mean
limit limit deviation limit limit deviation
0,5 64,5 72,0 56,7 6,5 −23,1 −15,1 −29,6 7,4
0,63 64,9 73,0 56,7 6,9 −23,8 −17,6 −29,4 5,9
0,8 64,7 74,0 56,7 7,1 −27,5 −25,4 −29,0 1,9
1 62,5 72,0 55,8 6,7 −30,5 −26,5 −35,7 4,6
1,25 59,2 70,1 50,6 7,3 −34,0 −27,8 −43,8 6,4
1,6 58,6 68,6 50,5 6,8 −46,3 −30,2 −63,0 14,8
2 52,8 66,2 41,7 7,7 −61,9 −33,6 −86,6 23,3
2,5 39,2 50,9 30,3 6,5 −76,7 −38,4 −102,0 29,0
3,15 26,3 33,3 22,4 3,6 −83,7 −44,0 −107,6 30,1
4 18,3 22,1 15,5 2,4 −86,4 −50,9 −111,6 27,0
5 14,9 17,8 11,8 2,2 −92,3 −60,0 −117,5 24,6
6,3 11,6 14,4 9,3 1,9 −103,6 −77,6 −127,7 20,7
8 8,4 10,3 6,9 1,3 −113,8 −93,8 −135,2 16,9
10 6,7 8,8 5,2 1,3 −116,9 −93,7 −138,4 18,7

10 © ISO 2019 – All rights reserved

Key
X frequency in Hz
Y1 modulus in kg
Y2 phase in °
NOTE For an explanation of the curves, see 4.1.
Figure 4 — Mean (target) and range of idealized values for the apparent mass of the seated body
without a back support under y-axis vibration
4.5 Apparent mass of the seated body under z-axis vibration
The modulus and phase of the apparent mass of the seated body with and without a back support are
given in Tables 5 and 6, respectively, and (for illustration) in Figures 5 and 6 as a function of frequency,
for the z-axis direction of excitation. According to the definitions, the modulus is given in terms of
kilograms for apparent mass. The table and diagram contain three values of modulus and phase at each
frequency. Numerical values are quoted up to four significant figures for the purpose of calculation,
and do not reflect the precision of knowledge of the apparent mass. Linear interpolation is permitted to
obtain values at frequencies other than those listed in Tables 5 and 6 at one-third-octave band centre
frequencies.
Applications shall generate/employ values of apparent mass between the upper and lower limits given
in Tables 5 and 6 at any frequency, and represent “to the body” transfer functions applicable to the
seated human body under the conditions specified and over the frequency range of 0,5 Hz to 20 Hz.
See 4.1 for more details.
4.6 Applicability of values of apparent mass of the seated body under z-axis vibration
The values of apparent mass are applicable to the seated human body, subjected to sinusoidal or broad-
band random vertical vibration, while seated on a rigid surface with the feet resting flat on the base
platform and the back being supported and unsupported. The limits of applicability approximately
correspond to the range of measurement conditions over which data were obtained, as follows:
a) the posture is described as erect seated with or without backrest support, while the feet are
supported and vibrated;
b) the angle for the back support is ranging from 90° to 102° for the condition with a backrest support;
c) the mass of the subjects ranges from 62 kg to 106 kg for the condition with a backrest support, and
from 49 kg to 107 kg for the condition without a backrest support;
d) the RMS amplitude of unweighted sine and random excitation within the frequency range of 0,5 Hz
2 2
to 20 Hz is between 0,63 m/s and 1,0 m/s for the condition with a backrest support and between
2 2
0,8 m/s and 2,0 m/s for the condition without a backrest support.
Table 5 — Modulus and phase of the mean (target) and range of idealized apparent mass of the
seated body with a back support under z-axis vibration
Modulus Phase
Frequency
kg °
Hz
Upper Lower Standard Upper Lower Standard
Mean Mean
limit limit deviation limit limit deviation
0,5 58,6 62,4 52,5 3,6 0,2 0,8 −0,3 0,4
0,63 58,8 62,5 52,6 3,6 0,1 0,9 −0,5 0,5
0,8 58,7 62,6 53,0 3,4 −0,9 0,7 −8,5 2,7
1 58,8 63,2 54,0 3,2 −0,8 0,4 −6,7 2,1
1,25 59,2 64,1 53,9 3,4 −0,8 0,2 −5,3 1,6
1,6 60,6 66,5 56,7 3,5 −1,2 −0,2 −4,6 1,2
2 62,6 69,4 58,1 3,8 −1,7 −0,4 −5,0 1,2
2,5 66,1 74,9 60,5 4,5 −2,9 −0,9 −6,0 1,4
3,15 71,8 83,2 65,5 5,8 −5,4 −1,7 −9,8 2,6
4 81,5 95,9 74,0 6,8 −14,5 −5,2 −26,2 7,3
5 83,9 97,6 72,0 8,0 −30,8 −15,3 −51,0 12,3
6,3 72,5 89,5 56,2 10,6 −47,1 −35,0 −62,2 9,7
8 54,3 67,9 40,4 7,9 −57,9 −49,4 −68,6 6,2
10 45,1 52,6 34,7 5,8 −62,8 −50,5 −72,6 8,0
12,5 37,5 46,3 24,9 7,0 −71,1 −57,3 −80,0 8,9
16 26,4 34,2 13,9 6,9 −78,9 −64,8 −89,2 8,6
20 21,1 27,2 11,8 5,4 −79,0 −62,8 −90,0 9,2

12 © ISO 2019 – All rights reserved

Key
X frequency in Hz
Y1 modulus in kg
Y2 phase in °
NOTE For an explanation of the curves, see 4.1.
Figure 5 — Mean (target) and range of idealized values for the apparent mass of the seated body
with a back support under z-axis vibration

Table 6 — Modulus and phase of the mean (target) and range of idealized apparent mass of the
seated body without a back support under z-axis vibration
Modulus Phase
Frequency
kg °
Hz
Upper Lower Standard Upper Lower Standard
Mean Mean
limit limit deviation limit limit deviation
0,5 60,4 66,1 56,2 3,7 −1,1 2,8 −7,4 3,5
0,63 60,5 66,3 56,1 3,8 −1,4 3,5 −9,0 4,2
0,8 58,0 67,0 40,1 6,7 −1,3 2,8 −8,1 3,7
1 58,8 68,1 40,7 6,8 −2,5 2,2 −11,1 4,0
1,25 59,8 69,8 42,7 6,7 −2,8 1,1 −10,4 3,5
1,6 61,0 73,4 45,3 7,1 −3,7 −0,3 −10,1 3,1
2 61,8 77,1 47,9 8,2 −5,1 1,2 −11,6 3,4
2,5 65,9 83,0 51,6 8,8 −7,7 −1,4 −12,8 3,2
3,15 71,9 89,9 56,6 9,5 −11,5 −2,5 −20,2 4,3
4 81,2 105,8 60,3 12,5 −23,8 −6,9 −38,7 8,2
5 76,8 98,8 49,7 13,8 −46,3 −18,8 −64,2 12,9
6,3 55,5 74,1 36,3 10,4 −60,3 −43,5 −70,8 7,8
8 40,8 57,9 29,9 7,3 −63,9 −51,8 −72,9 5,8
10 32,7 47,7 22,5 6,3 −67,3 −50,9 −79,2 8,6
12,5 24,6 37,9 14,6 6,6 −74,3 −57,5 −85,6 8,8
16 17,2 28,9 8,4 5,4 −76,5 −64,8 −85,8 7,2
20 14,5 24,6 7,2 4,6 −73,6 −62,8 −84,7 7,5

14 © ISO 2019 – All rights reserved

Key
X frequency in Hz
Y1 modulus in kg
Y2 phase in °
NOTE For an explanation of the curves, see 4.1.
Figure 6 — Mean (target) and range of idealized values for the apparent mass of the seated body
without a back support under z-axis vibration
4.7 Apparent mass of the standing body under z-axis vibration
The modulus and phase of the apparent mass of the standing body are given in Table 7 and (for
illustration) in Figure 7 as a function of frequency, for the z-axis direction of excitation. According to
the definitions, the modulus is given in terms of kilograms for apparent mass. The table and diagram
contain three values of modulus and phase at each frequency. Numerical values are quoted up to four
significant figures for the purpose of calculation, and do not reflect the precision of knowledge of the
apparent mass. Linear interpolation is permitted to obtain values at frequencies other than those listed
in Table 7 at one-third-octave band centre frequencies.
Applications shall generate/employ values of apparent mass between the upper and lower limits given
in Table 7 at any frequency, and represent “to the body” transfer functions applicable to the standing
human body under the conditions specified and over the frequency range of 0,5 Hz to 20 Hz.
See 4.1 for more details.
4.8 Applicability of values of apparent mass of the standing body under z-axis vibration
The values of apparent mass are applicable to the standing human body on a rigid platform, subjected
to sinusoidal or broad-band random vertical vibration. The limits of applicability approximately
correspond to the range of measurement conditions over which data were obtained, as follows:
a) the posture is described as standing upright erect or relaxed;
b) the mass of the subjects ranges from 63 kg to 102 kg;
2 2
c) the RMS amplitude of unweighted sine and random excitation is between 0,5 m/s and 1,0 m/s
over the frequency range of 0,5 Hz to 20 Hz.
Table 7 — Modulus and phase of the mean (target) and range of idealized apparent mass of the
standing body under z-axis vibration
Modulus Phase
Frequency
kg °
Hz
Upper Lower Standard Upper Lower Standard
Mean Mean
limit limit deviation limit limit deviation
0,5 78,3 86,8 73,5 7,4 −0,1 0,0 −0,3 0,2
0,63 78,3 86,8 73,5 7,4 −0,1 0,0 −0,3 0,2
0,8 79,8 88,6 75,0 7,6 −0,2 0,0 −0,4 0,2
1 79,8 87,1 75,7 6,4 −0,4 −0,2 −0,6 0,2
1,25 80,0 85,7 76,3 5,0 −1,6 −1,0 −2,7 1,0
1,6 81,2 87,3 77,3 5,3 −4,4 −1,7 −9,4 4,3
2 82,3 90,5 78,2 5,8 −6,3 −2,2 −15,3 6,4
2,5 86,1 95,3 81,6 6,2 −8,7 −3,8 −21,0 8,2
3,15 88,3 103,4 71,5 11,7 −12,3 −6,0 −28,8 11,1
4 99,3 120,3 77,4 15,8 −20,6 −11,2 −44,9 16,2
5 114,7 142,0 92,3 18,8 −33,1 −23,3 −56,1 15,5
6,3 111,0 131,9 97,1 14,4 −55,2 −46,4 −76,5 14,3
8 79,1 99,9 67,0 12,8 −63,3 −53,6 −84,8 14,5
10 61,9 68,3 52,1 6,4 −62,4 −55,6 −74,5 8,6
12,5 54,7 60,8 43,1 7,2 −71,5 −61,7 −89,2 12,2
16 43,8 49,0 36,5 5,6 −88,2 −74,5 −114,2 18,2
20 36,4 41,5 27,0 6,2 −95,5 −82,9 −115,9 15,1

16 © ISO 2019 – All rights reserved

Key
X frequency in Hz
Y1 modulus in kg
Y2 phase in °
NOTE For an explanation of the curves, see 4.1.
Figure 7 — Mean (target) and range of idealized values for the apparent mass of the standing
body under z-axis vibration
5 Seat-to-head transmissibility of the seated human body under vertical
vibration
5.1 Definition of values of seat-to-head transmissibility
The modulus and phase of the seat-to-head transmissibility of the seated body are given in Table 8
and (for illustration) in Figure 8 as a function of frequency, for the vertical direction of excitation. In
accordance with the definition, the modulus is non-dimensional and represents the ratio of acceleration
transmitted to the head to the acceleration measured at the buttocks. The table and diagram contain
three values of modulus and phase at each frequency. Numerical values are quoted up to four significant
figures for the purpose of calculation, and do not reflect the precision of knowledge of the seat-to-head
transmissibility. Linear interpolation is permitted to obtain values at frequencies other than those
listed in Table 8 at one-third-octave band centre frequencies.
The upper and lower limiting values at each one-third-octave band centre frequency encompass the
mean values of all data sets selected, and are shown by continuous curves in Figure 8. The central value
at each frequency, shown by dashed curves in Figure 8, provides an estimate of the weighted mean of
all data sets selected, and forms the target value for all applications. The standard deviations computed
with respect to the weighted mean (target) values are also listed in Table 8.
Applications shall generate/employ values of seat-to-head transmissibility between the upper and
lower limits given in Table 8 at any frequency, and represent “through the body” transfer functions
applicable to the seated human body under the conditions specified and over the frequency range of
0,5 Hz to 20 Hz.
If an application only satisfies the requirements of this document at certain frequencies, then those
frequencies should be stated in any description of the application.
Table 8 — Modulus and phase of the mean (target) and range of idealized seat-to-head
transmissibility of the seated body under z-axis vibration
Phase
Modulus
Frequency
°
Hz
Upper Lower Standard Upper Lower Standard
Mean Mean
limit limit deviation limit limit deviation
0,5 0,97 1,02 0,87 0,06 0,0 0,0 −0,1 0,01
0,63 0,98 1,02 0,87 0,06 −0,1 −0,1 −0,1 0,02
0,8 0,98 1,03 0,87 0,06 −1,5 −0,1 −3,0 2,1
1 1,00 1,04 0,86 0,07 −1,7 0,0 −5,0 2,9
1,25 1,02 1,09 0,86 0,08 −2,7 −0,1 −6,0 3,0
1,6 1,06 1,15 0,87 0,10 −3,2 −0,2 −6,3 3,1
2 1,10 1,24 0,93 0,11 −4,2 −0,2 −7,8 3,8
2,5 1,19 1,38 1,04 0,12 −5,2 −1,1 −10,1 4,1
3,15 1,30 1,50 1,10 0,15 −6,4 −2,6 −13,8 5,1
4 1,54 1,80 1,31 0,19 −11,8 4,3 −21,1 11,5
5 1,59 2,05 1,26 0,27 −23,4 1,8 −37,7 18,1
6,3 1,18 1,47 0,92 0,22 −45,6 −31,3 −57,6 12,4
8 0,94 1,27 0,61 0,25 −61,9 −44,9 −73,2 12,6
10 0,88 1,08 0,62 0,17 −71,3 −46,7 −88,8 17,9
12,5 0,74 0,90 0,47 0,17 −82,7 −64,1 −95,9 14,0
16 0,64 0,75 0,48 0,11 −97,0 −87,1 −105,7 9,1
20 0,57 0,66 0,42 0,11 −108,2 −98,3 −119,7 9,9
5.2 Applicability of values of seat-to-head transmissibility
The values of seat-to-head transmissibility are applicable to the seated human body subjected to
sinusoidal or broad-band random vertical vibration, while seated on a rigid surface with the back
being unsupported. Both conditions of feet being supported on a vibrating platform and hanging freely
are integrated for the purpose of defining seat-to-head transmissibility. The limits of applicability
approximately correspond to the range of measurement conditions over which data were obtained, as
follows:
a) the posture is described as erect seated without backrest support, while the feet may be
supported or not;
b) the mass of the subjects ranges from 58 kg to 99 kg;
18 © ISO 2019 – All rights reserved

2 2
c) the RMS amplitude of unweighted sine and random excitation is between 1,0 m/s and 2,8 m/s
over the frequency range of 0,5 Hz to 20 Hz.
Key
X frequency in Hz
Y1 modulus
Y2 phase in °
NOTE For an explanation of the curves, see 5.1.
Figure 8 — Mean (target) and range of idealized values for the seat-to-head transmissibility of
the seated body under z-axis vibration
Annex A
(informative)
Identification of the data used to define the range of idealized
apparent mass and seat-to-head transmissibility
[36]
A set of selection rules are defined for selecting the published data to be used for the synthesis . Only
those data sets satisfying all of the following conditions were considered:
a) data sets reporting either the magnitude or the magnitude and phase of the biodynamic response
function;
b) data sets derived using adult subjects with body mass ranging from approximatively 55 kg to 110 kg;
c) data sets reported under either sinusoidal or random vibration within the 0,5 Hz to 20 Hz frequency
range for the vertical direction, while those for the horizontal direction were limited up to 10 Hz;
d) data sets acquired under vibration of unweighted RMS magnitude lower than or equal to 2 m/s ;
e) data sets acquired with clearly defined subject while those reporting a single subject data were
carefully examined;
f) head acceleration data for seat-to-head transmissibility were acquired using an accelerometer
positioned either on a bite-bar or at the top of the skull.
A set of rejection criteria has been added:
1) data sets with unsupported feet (for data involving apparent mass/driving-point mechanical
impedance only), with feet not vibrated or with the feet condition not clearly identified;
2) data sets involving children;
3) data sets for automotive posture;
4) data sets not reporting the total body mass;
5) studies involving only one subject, except for the standing body posture, where the number of
available data sets is limited;
6) studies where the mean response could not be obtained from individual data;
7) studies reporting response at a few discrete frequencies;
8) data sets that are considered outliers (large variation in the standard deviation of the idealized
apparent mass magnitude or phase when the outlier is removed from the data set).
Tables A.1 to A.7 identify the data sets considered for driving-point mechanical impedance and apparent
mass, while Table A.8 identifie
...