Underwater acoustics - Hydrophones - Properties of hydrophones in the frequency range 1 Hz to 500 kHz

IEC 60500:2017 specifies the relevant characteristics and properties of hydrophones in the frequency range 1 Hz to 500 kHz, and specifies how to report these characteristics. Provides guidance on the choice of a hydrophone with appropriate performance for a specific application. This standard is applicable to: - hydrophones employing piezoelectric sensor elements, designed to respond to sound pressure in water and measure underwater acoustical signals; - hydrophones with or without an integral pre-amplifier. This new edition includes the following significant technical changes with respect to the previous edition: - the format and scope of IEC 60500 have been changed to be compatible with other IEC standards; - the upper limit of the frequency range of hydrophones has been expanded.

Unterwasserakustik - Hydrophone - Eigenschaften von Hydrophonen im Frequenzbereich von 1 Hz bis 500 kHz

Acoustique sous-marine - Hydrophones - Propriétés des hydrophones dans la bande de fréquences de 1 Hz à 500 kHz

L'IEC 60500:2017 spécifie les caractéristiques et les propriétés pertinentes des hydrophones dans la bande de fréquences de 1 Hz à 500 kHz, ainsi que la manière de déclarer ces caractéristiques. Cette norme donne des lignes directrices relatives au choix d’un hydrophone présentant des performances appropriées pour une application spécifique. Le présent document est applicable aux: - hydrophones employant des éléments sensibles piézoélectriques conçus pour répondre à la pression acoustique dans l’eau et mesurer les signaux acoustiques sous-marins; - hydrophones avec ou sans préamplificateur intégré. Cette nouvelle édition inclut les modifications techniques majeures suivantes par rapport à l’édition précédente: - le format et le domaine d’application de l’IEC 60500 ont été modifiés de manière à les rendre compatibles avec d'autres normes IEC; - la limite supérieure de la bande de fréquences des hydrophones a été étendue.

Podvodna akustika - Hidrofoni - Lastnosti hidrofonov v frekvenčnem območju od 1 Hz do 500 kHz (IEC 60500:2017)

Ta dokument določa ustrezne značilnosti in lastnosti hidrofonov v frekvenčnem območju od 1 Hz do 500 kHz in določa, kako poročati o teh značilnostih. Ne zajema zahtev glede zmogljivosti za določene vrste hidrofonov ali za njihovo specifično uporabo. Kljub temu so v informativnem dodatku opredeljene smernice za izbiro hidrofona z ustrezno zmogljivostjo za določeno uporabo.
Ta dokument se uporablja za:
• hidrofone s piezoelektričnimi senzornimi elementi, ki so zasnovani tako, da reagirajo na zvočni tlak v vodi in merijo podvodne zvočne signale;
• hidrofone z vgrajenim predojačevalnikom ali brez njega.

General Information

Status
Published
Publication Date
27-Jul-2017
Technical Committee
Drafting Committee
Current Stage
6060 - Document made available
Due Date
26-Jun-2017

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SLOVENSKI STANDARD
SIST EN 60500:2017
01-oktober-2017
3RGYRGQDDNXVWLND+LGURIRQL/DVWQRVWLKLGURIRQRYYIUHNYHQþQHPREPRþMXRG
+]GRN+] ,(&

Underwater acoustics - Hydrophones - Properties of hydrophones in the frequency range

1 Hz to 500 kHz (IEC 60500:2017)
Ta slovenski standard je istoveten z: EN 60500:2017
ICS:
17.140.99 Drugi standardi v zvezi z Other standards related to
akustiko acoustics
SIST EN 60500:2017 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60500:2017
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SIST EN 60500:2017
EUROPEAN STANDARD EN 60500
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2017
ICS 17.140.50
English Version
Underwater acoustics - Hydrophones -
Properties of hydrophones in the frequency range
1 Hz to 500 kHz
(IEC 60500:2017)
Acoustique sous-marine - Hydrophones - Unterwasserakustik - Hydrophone -

Propriétés des hydrophones dans la bande de fréquences Eigenschaften von Hydrophonen im Frequenzbereich

de 1 Hz à 500 kHz von 1 Hz bis 500 kHz
(IEC 60500:2017) (IEC 60500:2017)

This European Standard was approved by CENELEC on 2017-05-15. 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 CEN-CENELEC

Management Centre 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 CEN-CENELEC Management Centre has the

same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,

Switzerland, Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2017 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN 60500:2017 E
---------------------- Page: 3 ----------------------
SIST EN 60500:2017
EN 60500:2017
European foreword

The text of document 87/644/FDIS, future edition 2 of IEC 60500, prepared by IEC/TC 87 "Ultrasonics"

was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 60500:2017.

The following dates are fixed:
• latest date by which the document has to be implemented at (dop) 2018-02-15
national level by publication of an identical national
standard or by endorsement
• latest date by which the national standards conflicting with (dow) 2020-05-15
the document have to be withdrawn

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice

The text of the International Standard IEC 60500:2017 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 60565:2006 NOTE Harmonized as EN 60565:2007 (not modified).
IEC 62127-3:2007 NOTE Harmonized as EN 62127-3:2007 (not modified)
+ A1:2013 + A1:2013 (not modified).
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SIST EN 60500:2017
EN 60500:2017
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod),

the relevant EN/HD applies.

NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is

available here: www.cenelec.eu.
Publication Year Title EN/HD Year
ISO 266 1997 Acoustics - Preferred frequencies EN ISO 266 1997
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SIST EN 60500:2017
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SIST EN 60500:2017
IEC 60500
Edition 2.0 2017-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Underwater acoustics – Hydrophones – Properties of hydrophones in the
frequency range 1 Hz to 500 kHz
Acoustique sous-marine – Hydrophones – Propriétés des hydrophones dans la
bande de fréquences de 1 Hz à 500 kHz
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.140.50 ISBN 978-2-8322-4049-6

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 7 ----------------------
SIST EN 60500:2017
– 2 – IEC 60500:2017 © IEC 2017
CONTENTS

FOREWORD ........................................................................................................................... 3

1 Scope .............................................................................................................................. 5

2 Normative references ...................................................................................................... 5

3 Terms and definitions ...................................................................................................... 5

4 Symbols ........................................................................................................................ 11

5 Hydrophone characteristics ........................................................................................... 12

5.1 General ................................................................................................................. 12

5.2 Basic requirements ............................................................................................... 12

5.3 Sensitivity ............................................................................................................. 12

5.4 Frequency response ............................................................................................. 13

5.4.1 Stated operating frequency band ................................................................... 13

5.4.2 Frequency dependence ................................................................................. 13

5.5 Directional response ............................................................................................. 13

5.6 Dynamic range ...................................................................................................... 13

5.6.1 Linearity and overload sound pressure level .................................................. 13

5.6.2 Equivalent noise pressure spectral density level ............................................ 14

5.6.3 Conditions required ....................................................................................... 14

5.7 Electrical requirements ......................................................................................... 14

5.7.1 Electromagnetic interference ......................................................................... 14

5.7.2 Electrical characteristics ................................................................................ 14

5.8 Mechanical requirements ...................................................................................... 14

5.9 Environmental aspects .......................................................................................... 15

5.10 Stability of the sensitivity ...................................................................................... 15

5.10.1 Temperature stability ..................................................................................... 15

5.10.2 Depth stability ................................................................................................ 15

5.10.3 Time stability ................................................................................................. 15

6 Information to be supplied by the manufacturer ............................................................. 16

Annex A (informative) Recommendations for selecting hydrophones .................................... 18

A.1 General ................................................................................................................. 18

A.2 Sensitivity ............................................................................................................. 18

A.3 Self–noise performance ........................................................................................ 19

A.4 Frequency response ............................................................................................. 19

A.5 Directional response ............................................................................................. 20

A.6 Dynamic range ...................................................................................................... 20

A.7 Electrical connection ............................................................................................. 21

A.8 Stability of the sensitivity ...................................................................................... 21

A.8.1 Temperature stability ..................................................................................... 21

A.8.2 Depth stability ................................................................................................ 21

A.8.3 Time stability ................................................................................................. 21

Bibliography .......................................................................................................................... 22

Figure 1 – Angular co-ordinate system .................................................................................... 6

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SIST EN 60500:2017
IEC 60500:2017 © IEC 2017 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
UNDERWATER ACOUSTICS – HYDROPHONES – PROPERTIES OF
HYDROPHONES IN THE FREQUENCY RANGE 1 Hz TO 500 kHz
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

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 60500 has been prepared by IEC technical committee 87:

Ultrasonics.

This second edition cancels and replaces the first edition published in 1974. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition.
a) The format and scope of IEC 60500 have been changed to be compatible with

IEC 62127-3:2007 in accordance with ISO/IEC Directives, and has a good conformity with

IEC 60565:2006, making the suite of available standards for underwater sound a more

coordinated and coherent system.

b) The upper limit of the frequency range of hydrophones has been expanded from 100 kHz

to 500 kHz.

c) Technical requirements of hydrophone selecting are provided in Annex A, and the depth

range of the static pressure range of hydrophones has been expanded from 10 m to 100 m.

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SIST EN 60500:2017
– 4 – IEC 60500:2017 © IEC 2017
The text of this International Standard is based on the following documents:
FDIS Report on voting
87/644/FDIS 87/649/RVD

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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SIST EN 60500:2017
IEC 60500:2017 © IEC 2017 – 5 –
UNDERWATER ACOUSTICS – HYDROPHONES – PROPERTIES OF
HYDROPHONES IN THE FREQUENCY RANGE 1 Hz TO 500 kHz
1 Scope

This document specifies the relevant characteristics and properties of hydrophones in the

frequency range 1 Hz to 500 kHz, and specifies how to report these characteristics. It does

not cover performance requirements for specific hydrophone types, or for specific hydrophone

applications. However, guidance on the choice of a hydrophone with appropriate performance

for a specific application is given in an informative annex.
This document is applicable to:

• hydrophones employing piezoelectric sensor elements, designed to respond to sound

pressure in water and measure underwater acoustical signals;
• hydrophones with or without an integral pre-amplifier.
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 266:1997, Acoustics – Preferred frequencies
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
angular co-ordinate system
system used to designate the directional response pattern of the hydrophone

Note 1 to entry: The terms “horizontal directional response” and “vertical directional response” are often used for

representation of directional response in the xy-plane, and xz- (or yz-) planes respectively.

Note 2 to entry: “+z” is coincident with an axis of the hydrophone, and “−z” is in the direction of the hydrophone

cable.
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SIST EN 60500:2017
– 6 – IEC 60500:2017 © IEC 2017
IEC
Key
r radial distance
θ polar angle
ϕ azimuthal angle
Figure 1 – Angular co-ordinate system
3.2
end-of-cable capacitance

electrical capacitance measured at the end of the integral cable of a

hydrophone at a frequency well below any pronounced resonance
Note 1 to entry: End-of-cable capacitance is expressed in farad, F.

Note 2 to entry: The frequency is stated along with the value of end-of-cable capacitance. The end-of cable

capacitance is typically measured at a frequency of 1 kHz.
3.3
diffraction factor

ratio of the root-mean-square sound pressure averaged over the part of the hydrophone

designed to receive an incident plane wave sound pressure from a given direction to the free-

field root-mean-square sound pressure that would exist at the reference centre of the

hydrophone if the hydrophone was removed

[SOURCE: IEC 60565:2006 [1] , 3.4, modified – Replace “averaged pressure” with “root-

mean-square sound pressure averaged”, “receive sound” with “receive an incident plane wave

sound pressure from a given direction”, “free-field sound pressure” with “free-field root-mean-

square sound pressure”, and add “if the hydrophone was removed”.]
3.4
directional response

description, generally presented graphically, of the response of a

hydrophone, as a function of the direction of propagation of the incident plane sound wave, in

a specified plane through the reference centre, at a specified frequency

Note 1 to entry: The directional response pattern is usually presented in the form of a two dimensional polar

graph. The scale of the polar may be in terms of sensitivity level or as relative values normalized to the sensitivity

in a specified direction (often the direction of the principal axis). The relative values are sometimes presented in

decibels as a relative directional response level. See Figure 1 for description of angular co-ordinate system.

___________
Numbers in square brackets refer to the Bibliography.
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SIST EN 60500:2017
IEC 60500:2017 © IEC 2017 – 7 –
[SOURCE: IEC 62127-3:2007 [2], 3.1, modified – Add the specific context " hydrophone>" and Note 1 to entry.]
3.5
dynamic range

twenty times the logarithm to the base 10 of the ratio of the overload sound pressure in a

specified frequency band that produces an undistorted hydrophone output to the equivalent

bandwidth noise pressure at the hydrophone
Note 1 to entry: Dynamic range is expressed in decibel, dB.

[SOURCE: IEC 60565:2006 [1], 3.6, modified – Replace “ratio” with “twenty times the

logarithm to the base 10 of the ratio”, “maximum free-field sound pressure” with “overload

sound pressure in a specified frequency band”, and “equivalent noise pressure” with

“equivalent bandwidth noise pressure”.]
3.6
electrical impedance

complex valued quantity, the modulus of which is the ratio of the root-

mean-square voltage applied across the electrical terminals of a hydrophone to the resulting

root-mean-square current, and the argument of which is the phase difference between voltage

and current, at a specified frequency
Note 1 to entry: Electrical impedance of a hydrophone is expressed in ohm, Ω.

Note 2 to entry: Because the electrical impedance depends on the hydrostatic pressure, water temperature and

the length of the cable attached to the hydrophone, these parameters, as well as the frequency and the electrical

terminals where the electrical impedance is measured, should be specified.
3.7
electrical terminals

terminals across which the open-circuit voltage of a hydrophone is

measured
3.8
end-of-cable

specification that relates to the end of the integral cable of a hydrophone with or without an

integral pre-amplifier

Note 1 to entry: If the hydrophone is not provided with an integral cable, the specification relates to the output

connector firmly connected with the hydrophone, not any additional extension cable.

[SOURCE: IEC 62127-3:2007 [2], 3.4, modified – Replace “integral output cable if the

hydrophone or hydrophone assembly is provided with such a cable; if the hydrophone or

hydrophone assembly is not provided with an integral output cable, the specification relates to

the output connector firmly connected with the hydrophone or hydrophone assembly, not to an

extra cable” with “integral cable of a hydrophone with or without an integral pre-amplifier”. Add

Note 1 to entry.]
3.9
end-of-cable leakage resistance

ratio of the root-mean-square voltage across the end-of-cable electrical terminals of a

hydrophone to the direct root-mean-square current flowing through these terminals

Note 1 to entry: End-of-cable leakage resistance is expressed in ohm, Ω.

Note 2 to entry: The value of the voltage used during the determination of the end-of-cable leakage resistance

should be stated.
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SIST EN 60500:2017
– 8 – IEC 60500:2017 © IEC 2017

[SOURCE: IEC 60866:1987 [3], 3.13, modified – Replace “voltage across the electrical

terminals at the end of the hydrophone cable to the direct current” with “root-mean-square

voltage across the end-of-cable electrical terminals of a hydrophone to the direct root-mean-

square current”.]
3.10
equivalent bandwidth noise pressure

ratio of the root-mean-square noise voltage in the relevant frequency band present at the

electrical terminals of the hydrophone, in the absence of sound pressure or pressure

fluctuations at the hydrophone input, to its sensitivity in a specified frequency band

Note 1 to entry: Equivalent bandwidth noise pressure is expressed in pascal, Pa.
3.11
equivalent noise pressure spectral density
equivalent bandwidth noise pressure when its bandwidth is 1 Hz

Note 1 to entry: Equivalent noise pressure spectral density is expressed in pascal per square root of hertz,

-1/2
Pa ⋅ Hz .
3.12
equivalent noise pressure spectral density level

twenty times the logarithm to the base 10 of the ratio of the equivalent noise pressure spectral

density of a hydrophone, p , to a reference pressure spectral density, p
s s0

Note 1 to entry: Equivalent noise pressure spectral density level of a hydrophone is expressed in decibel, dB.

-1/2

Note 2 to entry: The value of reference pressure spectral density, p , is 1 µPa ⋅ Hz .

3.13
free field

sound field in a homogeneous and isotropic medium in which the effects of the boundaries are

negligible
[SOURCE: IEC 60565:2006 [1], 3.13]
3.14
free-field open-circuit complex sensitivity

complex valued quantity, the modulus of which is the free-field open-circuit sensitivity and the

argument of which is the sensitivity phase angle, for specified frequency and specified

direction of sound incidence at the position of the reference centre of the hydrophone if the

hydrophone was removed from the sound field
3.15
free-field open-circuit sensitivity

modulus of the free-field open-circuit complex sensitivity, which is equal to the ratio of the

open-circuit root-mean-square voltage at the end-of-cable of a hydrophone to the root-mean-

square sound pressure for specified frequency and specified direction of plane wave sound

incident on the position of the reference centre of the hydrophone in the undisturbed free field

if the hydrophone was removed

Note 1 to entry: Free-field open-circuit sensitivity is expressed in volt per pascal, V/Pa.

Note 2 to entry: The term ‘response’ is sometimes used instead of ‘sensitivity’.
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SIST EN 60500:2017
IEC 60500:2017 © IEC 2017 – 9 –
3.16
free-field open-circuit sensitivity level

twenty times the logarithm to the base 10 of the ratio of the free-field open-circuit sensitivity,

M , to a reference sensitivity, M
f ref

Note 1 to entry: Free-field open-circuit sensitivity level is expressed in decibel, dB.

Note 2 to entry: The value of reference sensitivity, M , is 1 V/µPa.
ref
3.17
hydrophone

electroacoustic transducer that produces electrical signals in response to water borne

pressure signals

Note 1 to entry: A hydrophone is designed to respond principally to underwater sound pressure.

Note 2 to entry: In general, a hydrophone may also produce a signal in response to non-acoustic pressure

fluctuations (for example, those existing in a turbulent boundary layer during conditions of high water flow).

Note 3 to entry: Hydrophone types include reference hydrophones and measuring hydrophones. Measuring

hydrophones are used in general measurements of sound fields, and reference hydrophones are principally used

for calibration purposes (for example in comparison calibrations with measuring hydrophones).

Note 4 to entry: Hydrophones are principally used for listening devices, but in reciprocity calibration, a

hydrophone is used as reciprocal transducer, not only acting as a hydrophone, but also as a projector (sound

source).

Note 5 to entry: A hydrophone which is integrated with a digital acquisition system is sometimes termed a “digital

hydrophone”, but the combination is best considered as a measuring system, not a hydrophone alone.

Note 6 to entry: If a hydrophone is connected to a charge amplifier, the sensitivity of the hydrophone is

sometimes described in terms of charge sensitivity, which is related to the voltage sensitivity of the hydrophone by

its electrical capacitance.

[SOURCE: IEC 60565:2006 [1], 3.16, modified – Replace “transducer” with “electroacoustic

transducer”, and “water borne acoustic signals” with “water borne pressure signals”. Replace

the note with Notes 1 to 6 to entry.]
3.18
open-circuit voltage

voltage appearing at the electrical terminals of a hydrophone when no current passes through

the terminals
Note 1 to entry: Open-circuit voltage at hydrophone is expressed in volt, V.

[SOURCE: IEC 60565:2006 [1], 3.19, modified – Delete "at hydrophone" from the term.]

3.19
overload sound pressure

ratio of the maximum root-mean-square sound pressure applied at the hydrophone to cause a

distorted voltage output with specified criteria (linearity) to a reference sound pressure at a

specified frequency
Note 1 to entry: Overload sound pressure is expressed in pascal, Pa.
Note 2 to entry: The distortion tolerance criteria should be specified.
3.20
overload sound pressure level

twenty times the logarithm to the base 10 of the ratio of the overload sound pressure, p , to a

reference sound pressure, p
Note 1 to entry: Overload sound pressure level is expressed in decibel, dB.
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SIST EN 60500:2017
– 10 – IEC 60500:2017 © IEC 2017
Note 2 to entry: The value of reference sound pressure, p , is 1 µPa.
3.21
phase angle

argument of the free-field open-circuit complex sensitivity, which is equal to the phase

difference between open-circuit voltage at the end-of-cable of a hydrophone and sound

pressure for specified frequency and specified direction of plane-wave sound incident on the

position of the reference centre of the hydrophone in the undisturbed free field if the

hydrophone was removed
3.22
pre-amplifier

active electronic device, often integrated into a particular hydrophone design, reducing the

hydrophone output impedance and amplifying the hydrophone output signal
Note 1 to entry: A pre-amplifier requires an electrical power supply voltage.

Note 2 to entry: The pre-amplifier may have a forward voltage transmission factor of less than one, i.e. it need not

necessarily be a volta
...

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