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.

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This document provides descriptive statistics of the hearing threshold deviation for populations
of otologically normal persons of various ages under monaural earphone listening conditions. It
specifies the following, for populations within the age limits from 18 years to 80 years for the range of
audiometric frequencies from 125 Hz to 8 000 Hz:
a) the expected median value of hearing thresholds given relative to the median hearing threshold at
the age of 18 years;
b) the expected statistical distribution above and below the median value.
For the frequencies from 3 000 Hz to 8 000 Hz, the median and statistical distribution for populations
above 70 years are presented for information only.
This document also provides for information the expected median values at audiometric frequencies
from 9 000 Hz to 12 500 Hz within the age limits from 22 years to 80 years.
The data are applicable for estimating the amount of hearing loss caused by a specific agent in a
population. Such a comparison is valid if the population under study consists of persons who are
otologically normal except for the effect of the specific agent. Noise exposure is an example of a specific
agent and for this application, selected data from this document are referred to as “database A” in
ISO 1999.
NOTE 1 ISO 1999:2013, Database A is based on a previous edition of ISO 7029.
The data may also be used to assess an individual’s hearing in relation to the distribution of hearing
thresholds which is normal for the person’s age group. However, it is not possible to determine for
an individual precisely which part of an observed hearing loss is attributable to an accumulation of
detrimental effects on the hearing which increase with age, and which part has been caused by other
factors such as noise.
The hearing threshold deviation as defined herein and the hearing threshold level as defined in other
International Standards (ISO 389-1, ISO 389-2, ISO 389-5, ISO 389-8, ISO 8253-1, ISO 8253-2, IEC 60645-
1) express the hearing threshold of an individual or an individual ear, respectively, relative to
— the expected median hearing threshold of 18-year-old age group of the same gender, or
— a reference zero level specified in various parts of ISO 389.
To the extent that the reference zero level represents the median of the 18-year-old population, the
values of the two terms will be the same.
NOTE 2 The values of these two are not always the same for some reasons. One reason is that the reference
zero level has been determined based on the hearing threshold levels of persons older than 18 years, including
those aged up to 25 years or to 30 years, who have slightly worse hearing sensitivity on average.
NOTE 3 ISO 28961 specifies the expected statistical distribution of hearing thresholds, expressed in sound
pressure level in decibels, for populations of otologically normal persons of the age from 18 years to 25 years
under binaural, free-field listening conditions. It enables the calculation not only at audiometric frequencies, but
also for other frequencies at one-third-octave intervals from 20 Hz to 16 000 Hz.

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This European Standard specifies the general principles required for Leak Detection by the acoustic emission (AE) testing. The Standard is addressed to the application of the methodology on structures and components, where a leak flow as result of pressure differences appears and generates AE.
It describes phenomena of the AE generation and influence of the nature of fluids, shape of the gap, wave propagation and environment.
The different application methods, instrumentation and presentation of AE results will be discussed. It also includes the guidelines for the preparation of application documents, which describe specific requirements for the application of the AE method.
Different application examples will be given.
Unless otherwise specified in the referencing documents, the minimum requirements of this standard are applicable.

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ISO 7029:2017 provides descriptive statistics of the hearing threshold deviation for populations of otologically normal persons of various ages under monaural earphone listening conditions. It specifies the following, for populations within the age limits from 18 years to 80 years for the range of audiometric frequencies from 125 Hz to 8 000 Hz:
a) the expected median value of hearing thresholds given relative to the median hearing threshold at the age of 18 years;
b) the expected statistical distribution above and below the median value.
For the frequencies from 3 000 Hz to 8 000 Hz, the median and statistical distribution for populations above 70 years are presented for information only.
ISO 7029:2017 also provides for information the expected median values at audiometric frequencies from 9 000 Hz to 12 500 Hz within the age limits from 22 years to 80 years.

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Describes a laboratory method and in situ methods for the determination of the sound insulation performance of sound-protecting cabins. Applicable to sound-protecting cabins with a leak ratio smaller than 2 %.

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ISO 7235:2003 specifies methods for determining
the insertion loss, in frequency bands, of ducted silencers with and without airflow,
the sound power level, in frequency bands, of the flow noise (or regenerated sound) generated by ducted silencers,
the total pressure loss of silencers with airflow, and
the transmission loss, in frequency bands, of air-terminal units.
The measurement procedures are intended for laboratory measurements at ambient temperature. Measurements on silencers in situ are specified in ISO 11820.
It is to be noted that the results determined in a laboratory according to ISO 7235:2003 will not necessarily be the same as those obtained in situ (installation), as different sound and flow fields will yield different results. For example, the pressure loss will be lower under laboratory conditions than in situ, but will be comparable between different laboratories.
ISO 7235:2003 is applicable to all types of silencer including silencers for ventilating and air-conditioning systems, air intake and exhaust of flue gases, and similar applications. Other passive air-handling devices, such as bends, air-terminal units or T-connectors, can also be tested using this International Standard.
It is not applicable to reactive silencers used for motor vehicles.

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Applies to loudspeakers conforming to IEC 61305-5 and intended for home use to establish standards for comparison of the sound characteristics of various loudspeakers with each other. Two test procedures are described: single stimulus ratings; paired comparisons.

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Applies to measurements on silencers in practical applications for acoustic analysis, acceptance tests and similar evaluations. Depending on the method used, the measurement is either of insertion loss or transmission loss.

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Cancels and replaces ISO 3743 (1988). Specifies a relatively simple engineering method for determining the sound power levels of small, movable noise sources. In this direct method the A-weighted sound power level of the source under test is determined from a single A-weighted sound pressure level measurement at each microphone position, rather than from a summation of octave-band levels. This method eliminates the need for a reference sound source, but requires the use of a special reverberation test room.

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Specifies a laboratory substitution method to determine the insertion loss of ducted circular and rectangular silencers without flow, as well as other duct elements for use in ventilating and air-conditioning systems.

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This International Standard specifies a laboratory substitution method to determine the insertion loss without flow of ducted, mainly absorbent, circular and rectangular silencers as well as other duct elements for use in ventilating and air-conditioning systems.  Note 1: Laboratory measurement procedures for ducted silencers with superimposed flow are described in ISO 7235.  This International Standard is applicable to silencers where the design velocity does not exceed 15 m/s. As the method does not include self-generated flow noise, this International Standard is not suitable for tests on silencers where this type of noise is of great importance for the evaluation of the silencer performance.  The insertion loss determined according to this International Standard in a laboratory will not necessarily be the same as the insertion loss that will be obtained in an installation in the field. Different sound and flow fields in the duct will yield different results. As this International Standard requires regular test ducts, the results may include some flanking transmission via structural vibrations in the duct walls, that sets an upper limit to the insertion loss that can be determined.  Note 2: ISO 7235 gives methods for determining this limit.  This International Standard is intended to be used for circular silencers with diameters of 80 mm to 2 000 mm or rectangular silencers with cross-sectional areas within the same range.

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This part of ISO 3743 specifies a relatively simple engineering method for determining the sound power levels of small, movable noise sources. The measurements are carried out when the source is installed in a specially designed room having a specified reverberation time over the frequency range of interest. The A-weighted sound power level of the source under test is determined from a single A-weighted sound pressure level measurement at each microphone position, rather than from a summation of octave-band levels. This direct method eliminates the need for a reference sound source, but requires the use of a special reverberation test room. The direct method is based on the premise that the sound pressure level, averaged in space and time in the test room, can be used to determine the sound power level emitted by the source. The properties of the special reverberation test room are chosen so that the room's influence on the sound power output of the equipment under test is small. The number of microphone positions and source locations required in the test room are specified. Guidelines for the design of special reverberation rooms are given in annex B.  In addition to the directi method, a comparison method is also described (see 8.3). However, since the requirements on the test room for the comparison method of ISO 3743-1 are considerably less restrictive, it is recommended that the comparison method of ISO 3743-1 be used if a special reverberation test room is not available.  Note: Precision methods for the determination of the sound power levels of small noise sources are specified in ISO 3741 and ISO 3745.

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This International Standard specifies the substitution method for determining the insertion loss of ducted silencers. It sets out requirements for determining:  - the insertion loss, in frequency bands, of silencers with and without air flow;  - the sound power level, in frequency bands, of the flow noise generated by silencers;  - the total pressure loss of silencers with air flow.  The measurement procedures are intended for laboratory measurements on silencers but may also be used for in situ measurements on silencers if the requirements of this International Standard can be met.  This International Standard applies to silencers for ventilating air-conditioning systems which are usually connected to ducts or splitter absorbers mounted in ducts. Other duct elements, such as bends or T-connectors, may also be tested using this Intenational Standard.  This International Standard does not apply to reactive silencers used for motor vehicles.  [There is a note on the precision of the method]

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Specification for the range of audiometric frequencies from 125 to 8000 Hz and for groups of otologically normal persons of a given age within the age limits of 18 to 70 years inclusive : a) the expected value of the median hearing threshold shift relative to a group of persons 18 years of age; b) the expected statistical distribution above and below the median value.

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