EN 62127-1:2007

SLOVENSKI STANDARD
01-januar-2008
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SIST EN 61101:2002
SIST EN 61220:2002
SIST EN 62092:2002
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Ultrasonics - Hydrophones - Part 1: Measurement and characterization of medical
ultrasonic fields up to 40 MHz (IEC 62127-1:2007)
Ultraschall - Hydrophone - Teil 1: Messung und Charakterisierung von medizinischen
Ultraschallfeldern bis zu 40 MHz (IEC 62127-1:2007)
Ultrasons - Hydrophones - Partie 1: Mesures et caractérisation des champs ultrasonores
médicaux jusqu'a 40 Mhz (IEC 62127-1:2007)
Ta slovenski standard je istoveten z: EN 62127-1:2007
ICS:
11.040.01 Medicinska oprema na Medical equipment in general
splošno
17.140.50 Elektroakustika Electroacoustics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 62127-1
NORME EUROPÉENNE
October 2007
EUROPÄISCHE NORM
ICS 17.140.50 Partially supersedes EN 61101:1993, EN 61102:1993 + A1:1994, EN 61220:1995 and EN 62092:2001

English version
Ultrasonics -
Hydrophones -
Part 1: Measurement and characterization
of medical ultrasonic fields up to 40 MHz
(IEC 62127-1:2007)
Ultrasons -  Ultraschall -
Hydrophones - Hydrophone -
Partie 1: Mesures et caractérisation Teil 1: Messung und Charakterisierung
des champs ultrasonores médicaux von medizinischen Ultraschallfeldern
jusqu'à 40 Mhz bis zu 40 MHz
(CEI 62127-1:2007) (IEC 62127-1:2007)

This European Standard was approved by CENELEC on 2007-09-01. CENELEC 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 Central Secretariat or to any CENELEC 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 CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2007 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62127-1:2007 E
Foreword
The text of document 87/352/CDV, future edition 1 of IEC 62127-1, prepared by IEC TC 87, Ultrasonics,
was submitted to the IEC-CENELEC parallel Unique Acceptance Procedure and was approved by
CENELEC as EN 62127-1 on 2007-09-01.
EN 62127-1, EN 62127-2 and EN 62127-3 are being published simultaneously. Together these European
Standards cancel and replace EN 61101:1993, EN 61102:1993 + A1:1994, EN 61220:1995 and
EN 62092:2001.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2008-06-01
– latest date by which the national standards conflicting
(dow) 2010-09-01
with the EN have to be withdrawn
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 62127-1:2007 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60601-2-37 NOTE  Harmonized as EN 60601-2-37:2001 (not modified).
IEC 61157 NOTE  Harmonized as EN 61157:1994 (not modified).
IEC 61161 NOTE  Harmonized as EN 61161:2007 (not modified).
IEC 62359 NOTE  Harmonized as EN 62359:2005 (not modified).
__________
- 3 - EN 62127-1:2007
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application 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.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

IEC 60050-801 1994 International Electrotechnical Vocabulary - -
(IEV) -
Chapter 801: Acoustics and electroacoustics

1) 2)
IEC 60565 - Underwater acoustics - Hydrophones - EN 60565 2007
Calibration in the frequency range 0,01 Hz
to 1 MHz
IEC/TR 60854 1986 Methods of measuring the performance of - -
ultrasonic pulse-echo diagnostic equipment

1)
IEC 61689 - Ultrasonics - Physiotherapy systems - Field EN 61689 2007
specifications and methods of measurement
in the frequency range 0,5 MHz to 5 MHz

1) 2)
IEC 61828 - Ultrasonics - Focusing transducers - EN 61828 2001
Definitions and measurement methods
for the transmitted fields
1) 2)
IEC 61846 - Ultrasonics - Pressure pulse lithotripters - EN 61846 1998
Characteristics of fields
1) 2)
IEC 61847 - Ultrasonics - Surgical systems - EN 61847 1998
Measurement and declaration of the basic
output characteristics
1) 2)
IEC 62127-2 - Ultrasonics - Hydrophones - EN 62127-2 2007
Part 2: Calibration for ultrasonic fields
up to 40 MHz
1) 2)
IEC 62127-3 - Ultrasonics - Hydrophones - EN 62127-3 2007
Part 3: Properties of hydrophones for
ultrasonic fields up to 40 MHz

ISO 16269-6 2005 Statistical interpretation of data - - -
Part 6: Determination of statistical tolerance
intervals
ISO/IEC Guide 98 1995 Guide to the expression of uncertainty in - -
measurement
1)
Undated reference.
2)
Valid edition at date of issue.

IEC 62127-1
Edition 1.0 2007-08
INTERNATIONAL
STANDARD
Ultrasonics – Hydrophones –
Part 1: Measurement and characterization of medical ultrasonic fields up to
40 MHz
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XC
ICS 17.140.50 ISBN 2-8318-9276-7

– 2 – 62127-1 © IEC:2007(E)
CONTENTS
FOREWORD.5
INTRODUCTION.7

1 Scope and object.8
2 Normative references .8
3 Terms, definitions and symbols .9
4 List of symbols .24
5 Measurement requirements .26
5.1 Requirements for hydrophones and amplifiers .26
5.1.1 Introduction .26
5.1.2 General .26
5.1.3 Sensitivity of a hydrophone.26
5.1.4 Directional response of a hydrophone.26
5.1.5 Effective hydrophone radius .27
5.1.6 Choice of the size of a hydrophone active element .27
5.1.7 Bandwidth .28
5.1.8 Linearity .28
5.1.9 Hydrophone signal amplifier .29
5.1.10 Hydrophone cable length and amplifiers .29
5.2 Requirements for positioning and water baths .29
5.2.1 General .29
5.2.2 Positioning systems.30
5.2.3 Water bath.31
5.3 Requirements for data acquisition and analysis systems .32
5.4 Recommendations for ultrasonic equipment being characterized .32
6 Measurement procedure.32
6.1 General .32
6.2 Preparation and alignment.33
6.2.1 Preparation.33
6.2.2 Aligning an ultrasonic transducer and a hydrophone.33
6.3 Measurement .33
6.4 Analysis .33
6.4.1 Corrections for restricted bandwidth and spatial resolution .33
6.4.2 Uncertainties .33
7 Beam characterization.34
7.1 General .34
7.2 Primary pressure parameters .35
7.2.1 General .35
7.2.2 Peak-compressional acoustic pressure and peak-rarefactional
acoustic pressure .36
7.2.3 Spatial-peak rms acoustic pressure .36
7.2.4 Non-linear propagation parameter .36
7.2.5 Intensity parameters using instantaneous acoustic pressure.37
7.2.6 Intensity parameters using pulse-pressure-squared integral .37
7.2.7 Derived ultrasonic power .39
8 Requirements for specific ultrasonic fields.40

62127-1 © IEC:2007(E) – 3 –
8.1 General .40
8.2 Diagnostic fields.40
8.2.1 Simplified procedures and guidelines.40
8.2.2 Pulsed wave diagnostic equipment .41
8.2.3 Continuous wave diagnostic equipment .41
8.3 Therapy fields .42
8.3.1 Physiotherapy equipment .42
8.3.2 Hyperthermia.42
8.4 Surgical fields .42
8.4.1 Lithotripters and pressure pulse sources for other therapeutic
purposes .42
8.4.2 Low frequency surgical applications .43
8.5 Fields from other medical applications.43
9 Compliance statement .43
9.1 General .43
9.2 Maximum probable values .43
9.3 Sampling .44

Annex A (informative) General rationale .45
Annex B (informative) Hydrophones and positioning .47
Annex C (informative) Acoustic pressure and intensity.53
Annex D (informative) Voltage to pressure conversion .55
Annex E (informative) Correction for spatial averaging.60
Annex F (informative) Acoustic output parameters for multi-mode medical ultrasonic
fields in the absence of scan-frame synchronization .62
Annex G (informative) Propagation medium and degassing .68
Annex H (informative) Specific ultrasonic fields.69
Annex I (informative) Assessment of uncertainty in the acoustic quantities obtained by
hydrophone measurements.72
Annex J (informative) Transducer and hydrophone positioning systems.74
Annex K (informative) Beamwidth midpoint method.75

Bibliography.76

Figure 1 – Schematic diagram of the different planes and lines in an ultrasonic field
(see also IEC 61828) .11
Figure 2 – Schematic diagram of the method of determining pulse duration .35
Figure D.1 – A flow diagram of the hydrophone deconvolution process .56
Figure D.2 – Example of waveform deconvolution.59
Figure J.1 – Schematic diagram of the ultrasonic transducer and hydrophone degrees
of freedom .74

Table 1 – Acoustic parameters appropriate to various types of medical ultrasonic
equipment.34
Table B.1 – Typical specification data for hydrophones, in this case given at 1 MHz .52
Table C.1 – Properties of distilled or de-ionized water as a function of temperature.54
Table D.1 – Method of conversion from a double- to a single-sided spectrum .57

– 4 – 62127-1 © IEC:2007(E)
Table D.2 – Method of conversion from a single- to a double-sided spectrum .58
Table F.1 – Main parameters defined in IEC standards .63
Table F.2 – List of parameters that are to be used or are to be deleted.64
Table K.1 – dB beamwidth levels for determining midpoints .75

62127-1 © IEC:2007(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ULTRASONICS – HYDROPHONES –
Part 1: Measurement and characterization of medical
ultrasonic fields up to 40 MHz

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62127-1 has been prepared by IEC technical committee 87:
Ultrasonics.
IEC 62127-1, IEC 62127-2 and IEC 62127-3 are being published simultaneously. Together
these cancel and replace IEC 60866:1987, IEC 61101:1991, IEC 61102:1991, IEC 61220:1993
and IEC 62092:2001.
The text of this standard is based on the following documents:
Enquiry draft Report on voting
87/352/CDV 87/371/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

– 6 – 62127-1 © IEC:2007(E)
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 62127 series, published under the general title Ultrasonics –
Hydrophones, can be found on the IEC website.
NOTE Words in bold in the text are defined in Clause 3.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC website under "http://webstore.iec.ch" in the
data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition; or
• amended.
A bilingual version of this publication may be issued at a later date.

62127-1 © IEC:2007(E) – 7 –
INTRODUCTION
The main purpose of this part of IEC 62127 is to define various acoustic parameters that can
be used to specify and characterize ultrasonic fields propagating in liquids, and, in particular,
water, using hydrophones. Measurement procedures are outlined that may be used to
determine these parameters. Specific device related measurement standards, for example
IEC 61689, IEC 61157, IEC 61847 or IEC 62359, can refer to this standard for appropriate
acoustic parameters.
The philosophy behind this standard is the specification of the acoustic field in terms of
acoustic pressure parameters, acoustic pressure being the primary measurement quantity
when piezoelectric hydrophones are used to characterize the field. Of course, if other
measurement devices come into use in the future, a new standard with additional definitions
and procedures will be necessary. Examples of such devices would be thermistors,
thermocouples or optical hydrophones.
Intensity parameters are specified in this standard, but these are regarded as derived
quantities that are meaningful only under certain assumptions related to the ultrasonic field
being measured.
– 8 – 62127-1 © IEC:2007(E)
ULTRASONICS – HYDROPHONES –
Part 1: Measurement and characterization of medical
ultrasonic fields up to 40 MHz

1 Scope and object
This part of IEC 62127 specifies methods of use of calibrated hydrophones for the
measurement in liquids of acoustic fields generated by ultrasonic medical equipment operating
in the frequency range up to 40 MHz.
The objectives of this standard are:
– to define a group of acoustic parameters that can be measured on a physically sound
basis;
– to define a second group of parameters that can be derived under certain assumptions
from these measurements, and called derived intensity parameters;
– to define a measurement procedure that may be used for the determination of acoustic
pressure parameters;
– to define the conditions under which the measurements of acoustic parameters can be
made in the frequency range up to 40 MHz using calibrated hydrophones;
– to define procedures for correcting, for limitations caused by the use of hydrophones with
finite bandwidth and finite active element size.
NOTE 1 Throughout this standard, SI units are used. In the specification of certain parameters, such as beam
areas and intensities, it may be convenient to use decimal multiples or submultiples. For example beam area may
2 2 2
be specified in cm and intensities in W/cm or mW/cm .
NOTE 2 The hydrophone as defined may be of a piezoelectric or an optic type. The introduction however implies
that optical hydrophones are not covered.
2 Normative references
The following referenced documents are indispensable for the application 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.
IEC 60050-801:1994, International Electrotechnical Vocabulary – Chapter 801: Acoustics and
electroacoustics
IEC 60565, Underwater acoustics – Hydrophones – Calibration in the frequency range 0,01 Hz
to 1 MHz
IEC/TR 60854:1986, Methods of measuring the performance of ultrasonic pulse-echo
diagnostic equipment
IEC 61689, Ultrasonics – Physiotherapy systems – Performance requirements and methods of
measurement in the frequency range 0,5 MHz to 5 MHz
IEC 61828, Ultrasonics – Focusing transducers – Definitions and measurement methods for
the transmitted fields
IEC 61846, Ultrasonics – Pressure pulse lithotripters – Characteristics of fields

62127-1 © IEC:2007(E) – 9 –
IEC 61847, Ultrasonics – Surgical systems – Measurement and declaration of the basic output
characteristics
IEC 62127-2, Ultrasonics – Hydrophones – Part 2: Calibration for ultrasonic fields up to
40 MHz
IEC 62127-3, Ultrasonics – Hydrophones – Part 3: Properties of hydrophones for ultrasonic
fields up to 40 MHz
ISO 16269-6:2005, Statistical interpretation of data – Part 6: Determination of statistical
tolerance intervals
ISO, Guide to the expression of uncertainty in measurement. Geneva, Switzerland:
International Organization for Standardization (ISO), 1995
NOTE The following standards rely on the proper use of this document.
IEC 61157, Standard means for the reporting of the acoustic output of medical diagnostic ultrasonic equipment
IEC 62359, Ultrasonics – Field characterization – Test methods for the determination of thermal and mechanical
indices related to medical diagnostic ultrasonic fields
IEC 61847, Ultrasonics – Surgical systems – Measurement and declaration of the basic output characteristics.
3 Terms, definitions and symbols
For the purposes of this document, the terms and definitions given in IEC 62127-2, IEC 62127-
3 and the following apply. It also includes definitions related to subjects in this document to be
used in particular medical ultrasound device standards.
3.1
acoustic pulse waveform
temporal waveform of the instantaneous acoustic pressure at a specified position in an
acoustic field and displayed over a period sufficiently long to include all significant acoustic
information in a single pulse or tone-burst, or one or more cycles in a continuous wave
NOTE 1 Temporal waveform is a representation (e.g oscilloscope presentation or equation) of the instantaneous
acoustic pressure.
NOTE 2 Definition adopted from IEC 60469-1.
3.2
acoustic repetition period
arp
pulse repetition period for non-automatic scanning systems and the scan repetition period
for automatic scanning systems, equal to the time interval between corresponding points of
consecutive cycles for continuous wave systems
NOTE The acoustic repetition period is expressed in seconds (s).
3.3
acoustic frequency
acoustic-working frequency
frequency of an acoustic signal based on the observation of the output of a hydrophone
placed in an acoustic field at the position corresponding to the spatial-peak temporal-peak
acoustic pressure
NOTE 1 The signal is analysed using either the zero-crossing acoustic-working frequency technique or a
spectrum analysis method. Acoustic-working frequencies are defined in 3.3.1 and 3.3.2.

– 10 – 62127-1 © IEC:2007(E)
NOTE 2 In a number of cases the present definition is not very helpful or convenient, especially for broadband
transducers. In that case, a full description of the frequency spectrum should be given in order to enable any
frequency-dependent correction to the signal.
NOTE 3 Acoustic frequency is expressed in hertz (Hz).
3.3.1
zero-crossing acoustic-working frequency
f
awf
this is determined according to the procedure specified in IEC/TR 60854
NOTE This frequency is intended for continuous wave systems only.
3.3.2
arithmetic-mean acoustic-working frequency
f
awf
arithmetic mean of the most widely separated frequencies f and f , within the range of three
1 2
times f , at which the magnitude of the acoustic pressure spectrum is 3 dB below the peak
magnitude
NOTE 1 This frequency is intended for pulse-wave systems only.
NOTE 2 It is assumed that f < f .
1 2
3.3.3
peak pulse acoustic frequency
f .
p
arithmetic-mean acoustic-working frequency of the pulse with the largest peak negative
acoustic pressure measured at the point of maximum peak negative acoustic pressure
NOTE Peak pulse acoustic frequency is expressed in hertz (Hz).
3.3.4
time average acoustic frequency
f
t
arithmetic-mean acoustic-working frequency of the time averaged acoustic pressure
spectrum of the acoustic signal measured at the point of maximum temporal average
intensity
NOTE Time average acoustic frequency is expressed in hertz (Hz).
3.4
azimuth axis
axis formed by the junction of the azimuth plane and the source aperture plane
(measurement) or transducer aperture plane (design)
NOTE 1 Definition adopted from IEC 61828:2001.
NOTE 2 See Figure 1.
62127-1 © IEC:2007(E) – 11 –
Z
X
Y
IEC  1638/07
Key
X  azimuth axis
Y  beam axis
Z  elevation axis
1  external transducer aperture plane
2  source aperture plane
3  aperture plane
4  beam area plane
5  beamwidth lines
6  azimuth plane, scan plane
7  elevation plane
8  longitudinal plane
9  principle longitudinal plane
Figure 1 – Schematic diagram of the different planes and lines in an ultrasonic field
(see also IEC 61828)
3.5
azimuth plane
for a scanning ultrasonic transducer: this is the scan plane; for a non-scanning ultrasonic
transducer: this is the principal longitudinal plane
NOTE 1 Definition adopted from IEC 61828:2001.
NOTE 2 See Figure 1.
– 12 – 62127-1 © IEC:2007(E)
3.6
bandwidth
BW
difference in the most widely separated frequencies f and f at which the magnitude of the
1 2
acoustic pressure spectrum becomes 3 dB below the peak magnitude, at a specified point in
the acoustic field
NOTE Bandwidth is expressed in hertz (Hz).
3.7
beam area
A
b
area in a specified plane perpendicular to the beam axis consisting of all points at which the
pulse-pressure-squared integral is greater than a specified fraction of the maximum value of
the pulse-pressure-squared integral in that plane
NOTE 1 If the position of the plane is not specified, it is the plane passing through the point corresponding to the
spatial-peak temporal-peak acoustic pressure in the whole acoustic field.
NOTE 2 In a number of cases, the term pulse-pressure-squared integral is replaced everywhere in the above
definition by any linearly related quantity, for example
a) in the case of a continuous wave signal the term pulse-pressure-squared integral is replaced by mean square
acoustic pressure as defined in IEC 61689,
b) in cases where signal synchronisation with the scanframe is not available the term pulse-pressure-squared
integral may be replaced by temporal average intensity
NOTE 3 Some specified levels are 0,25 and 0,01 for the −6 dB and −20 dB beam areas, respectively.
NOTE 4 Beam area is expressed in metres squared (m ).
NOTE 5 Definition is modified compared to that used in IEC 61828:2001.
3.8
beam axis
straight line that passes through the beam centrepoints of two planes perpendicular to the
line which connects the point of maximal pulse-pressure-squared integral with the centre of
the external transducer aperture
NOTE 1 The location of the first plane is the location of the plane containing the maximum pulse-pressure-
squared integral or, alternatively, is one containing a single main lobe which is in the focal Fraunhofer zone. The
location of the second plane is as far as is practicable from the first plane and parallel to the first with the same two
orthogonal scan lines (x and y axes) used for the first plane.
NOTE 2 In a number of cases, the term pulse-pressure-squared integral is replaced in the above definition by
any linearly related quantity, for example
a) in the case of a continuous wave signal the term pulse-pressure-squared integral is replaced by mean
square acoustic pressure as defined in IEC 61689,
b) in cases where signal synchronisation with the scanframe is not available the term pulse-pressure-
squared integral may be replaced by temporal average intensity.
NOTE 3 See Figure 1.
NOTE 4 Definition is modified compared to that used in IEC 61828:2001.
3.9
beam centrepoint
position determined by the intersection of two lines passing through the beamwidth
midpoints of two orthogonal planes, xz and yz
NOTE Definition adopted from IEC 61828:2001.
3.10
beamwidth midpoint
linear average of the location of the centres of beamwidths in a plane

62127-1 © IEC:2007(E) – 13 –
NOTE 1 The average is taken over as many beamwidth levels given in Table K.1 as signal level permits.
NOTE 2 Definition adopted from IEC 61828:2001.
3.11
beamwidth
w , w , w
6 12 20
greatest distance between two points on a specified axis perpendicular to the beam axis
where the pulse-pressure-squared integral falls below its maximum on the specified axis by
a specified amount
NOTE 1 In a number of cases, the term pulse-pressure-squared integral is replaced in the above definition by
any linearly related quantity, for example
a) in the case of a continuous wave signal the term pulse-pressure-squared integral is replaced by mean square
acoustic pressure as defined in IEC 61689,
b) in cases where signal synchronisation with the scanframe is not available the term pulse-pressure-squared
integral may be replaced by temporal average intensity.
NOTE 2 Commonly used beamwidths are specified at –6 dB, –12 dB and –20 dB levels below the maximum. The
decibel calculation implies taking 10 times the logarithm of the ratios of the integrals.
NOTE 3 Beamwidth is expressed in metres (m).
NOTE 4 Definition slightly modified to that in IEC 61828:2001.
3.12
broadband transducer
transducer that generates an acoustic pulse of which the bandwidth is greater than the
arithmetic-mean acoustic-working frequency
3.13
central scan line
for automatic scanning systems, the ultrasonic scan line closest to the symmetry axis of the
scan plane
3.14
diametrical beam scan
set of measurements of the hydrophone output voltage made while moving the hydrophone in
a straight line passing through a point on the beam axis and in a direction normal to the beam
axis.
NOTE The diametrical beam scan may extend to different distances on either side of the beam axis.
3.15
distance z
r
z
r
distance along the beam axis between the plane containing the peak-rarefactional acoustic
pressure and the external transducer aperture
NOTE The distance z is expressed in metres (m).
r
3.16
distance z
c
z
c
distance along the beam axis between the plane containing the peak-compressional
acoustic pressure and the external transducer aperture
NOTE The distance z is expressed in metres (m).
c
– 14 – 62127-1 © IEC:2007(E)
3.17
distance z
ppsi
z
ppsi
distance along the beam axis between the plane containing the maximum pulse-pressure-
squared integral and the external transducer aperture
NOTE The distance z is expressed in metres (m).
ppsi
3.18
distance z
spta
z
spta
distance along the beam axis between the plane containing the spatial-peak temporal-
average intensity and the external transducer aperture
NOTE 1 In practice, this distance is equal to the distance z .

ppsi
NOTE 2 The distance z is expressed in metres (m).
spta
3.19
distance z
offset
z
offset
distance along the beam axis between the plane containing the active face of the ultrasonic
transducer or ultrasonic transducer element group and the external transducer aperture
NOTE 1 Distance z is expressed in metres (m).
offset
NOTE 2 Definition adopted, with modified symbol, from IEC 61828:2001.
3.20
electric load impedance
Z
L
complex electric input impedance (consisting of a real and an imaginary part) to which the
hydrophone unit output cable is connected or is to be connected
NOTE The electric load impedance is expressed in ohms (Ω).
NOTE 2 Definition adopted from IEC 62127-3.
3.21
effective hydrophone radius
a , a , a
h h3 h6
radius of a stiff disc receiver hydrophone that has a predicted directional response function
with an angular width equal to the observed angular width
NOTE 1 The angular width is determined at a specified level below the peak of the directional response function.
For the specified levels of 3 dB and 6 dB, the radii are denoted by a and a respectively.
h3 h6
NOTE 2 The effective hydrophone radius is expressed in metres (m).
NOTE 3 The radius is usually the function of frequency. For representative experimental data, see [1].
NOTE 4 Definition adopted from IEC 62127-3.
3.22
effective radius of a non-focused ultrasonic transducer
a
t
radius of a perfect disc piston-like ultrasonic transducer that has a predicted axial acoustic
pressure distribution approximately equivalent to the observed axial acoustic pressure
distribution over an axial distance until at least the last axial maximum has passed
NOTE The effective radius of a non-focused ultrasonic transducer is expressed in metres (m).

62127-1 © IEC:2007(E) – 15 –
3.23
elevation axis
line in the source aperture plane (measurement) or transducer aperture plane (design) that
is perpendicular to the azimuth axis
NOTE 1 See Figure 1.
NOTE 2 Definition adopted from IEC 61828:2001.
3.24
elevation plane
longitudinal plane containing the elevation axis
NOTE 1 See Figure 1.
NOTE 2 Definition adopted from IEC 61828:2001.
3.25
end-of-cable loaded sensitivity
end-of-cable loaded sensitivity of a hydrophone (or hydrophone-assembly)
M (f)
L
ratio of the instantaneous voltage at the end of any integral cable or output connector of a
hydrophone or hydrophone-assembly, when connected to a specified electric load
impedance, to the instantaneous acoustic pressure in the undisturbed free field of a plane
wave in the position of the reference centre of the hydrophone if the hydrophone were
removed
NOTE 1 End-of-cable loaded sensitivity is expressed in volts per pascal (V/Pa).
NOTE 2 Definition adopted from IEC 62127-3.
3.26
end-of-cable open-circuit sensitivity
end-of-cable open-circuit sensitivity of a hydrophone
M (f)
c
ratio of the instantaneous open-circuit voltage at the end of any integral cable or output
connector of a hydrophone to the instantaneous acoustic pressure in the undisturbed free
field of a plane wave in the position of the reference centre of the hydrophone if the
hydrophone were removed
NOTE 1 End-of-cable open-circuit sensitivity is expressed in volts per pascal (V/Pa).
NOTE 2 Definition adopted from IEC 62127-3.
3.27
external transducer aperture
part of the surface of the ultrasonic transducer or ultrasonic transducer element group
assembly that emits ultrasonic radiation into the propagation medium.
NOTE 1 This surface is either directly in contact with the patient or is in contact with a water or liquid path to the
patient.
NOTE 2 See Figure 1.
NOTE 3 Definition adopted from IEC 61828:2001.
3.28
far field
acoustic (sound) field at distances from an ultrasonic transducer where the values of the
instantaneous acoustic pressure and particle velocity are substantially in phase (see also
IEV 801-23-30)
– 16 – 62127-1 © IEC:2007(E)
NOTE For the purposes of this standard, although strictly for circular planar ultrasonic transducers, the far field is
λ, where A is the output beam area and λ is the wavelength of the ultrasound
at a distance greater than A /π
ob ob
corresponding to the acoustic frequency.
3.29
hydrophone geometrical radius
a
g
radius defined by the dimensions of the active element of a hydrophone
NOTE The hydrophone geometrical radius is expressed in metres (m).
NOTE 2 Definition adopted from IEC 62127-3.
3.30
hydrophone
transducer that produces electric signals in response to waterborne acoustic signals
[IEV 801-32-26]
3.31
hydrophone assembly
combination of hydrophone and hydrophone pre-amplifier
NOTE Definition adopted from IEC 62127-3.
3.32
hydrophone pre-amplifier
active electronic device connected to, or to be connected to, a particular hydrophone and
reducing its output impedance
NOTE 1 A hydrophone pre-amplifier requires a supply voltage (or supply voltages).
NOTE 2 The hydrophone pre-amplifier may have a forward voltage transmission factor of less than one, i.e. it
need not necessarily be a voltage amplifier in the strict sense.
NOTE 3 Definition adopted from IEC 62127-3.
3.33
instantaneous acoustic pressure
p(t)
pressure minus the ambient pressure at a particular instant in time and at a particular point in
an acoustic field (see also IEV 801-01-19)
NOTE Instantaneous acoustic pressure is expressed in pascal (Pa).
3.34
instantaneous intensity
I(t)
acoustic energy transmitted per unit time in the direction of acoustic wave propagation per unit
area normal to this direction at a particular instant in time and at a particular point in an
acoustic field
NOTE 1 Instantaneous intensity is the product of instantaneous acoustic pressure and particle velocity. It is
difficult to measure intensity in the ultrasound frequency range. For the measurement purposes referred to in this
standard, and if it is reasonable to assume far field conditions, the instantaneous intensity, I is approximated as
p(t)
I(t) = (1)
ρ c
where
p(t) is the instantaneous acoustic pressure;
ρ is the density of the medium;

62127-1 © IEC:2007(E) – 17 –
c is the velocity of sound in the medium.
NOTE 2 Instantaneous intensity is expressed in watts per metre squared (W/m ).
3.35
longitudinal plane
plane defined by the beam axis and a specified orthogonal axis
NOTE 1 Definition adopted from IEC 61828:2001, 4.2.43
NOTE 2 See Figure 1.
3.36
mean peak acoustic pressure
p
m
the arithmetic mean of the peak-rarefactional acoustic pressure and the peak-compressional
acoustic pressure
NOTE Definition adopted from IEC 61949.
3.37
near field
region of the acoustic (sound) field of an ultrasonic transducer where the relative phase of
instantaneous acoustic pressure and the particle velocity is continually changing with
the
position in the acoustic (sound) field
NOTE For circular planar transducers, this is at a distance less than A /πλ, where A is the output beam area
1 1
group and λ is the wavelength of the ultrasound corresponding to the acoustic frequency.
3.38
non-linear propagation parameter
σ
m
index which permits the prediction of non-linear distortion of ultrasound for a specific
ultrasonic transducer, and is given by σ from [2]
m
1/ 2
1/ 2
ln()()F − l + F
ωβl
g g
σ = p (2)
m m
3 1/ 2
ρ c ()F − l
g
where
β is the non-linearity parameter (β = 1 + B/2A = 3,5 for pure water at 20 °C [2]);
ω is the angular frequency (ω =
...