EN 61012:1998

Filters for the measurement of audible sound in the presence of ultrasound

This standard specifies the electrical characteristics of a U-weighting filter mainly for use with sound level meters meeting the requirements of IEC 651 for the measurement of audible sound in the presence of ultrasound.

Filter für die Messung von hörbarem Schall im Beisein von Ultraschall

Filtres pour la mesure des sons audibles en présence d'ultrasons

Spécifie les caractéristiques électriques d'un filtre de pondération U, à utiliser principalement avec des sonomètres satisfaisant aux prescriptions de la CEI 651 pour la mesure des sons audibles en présence d'ultrasons.

Filters for the measurement of audible sound in the presence of ultrasound (IEC 61012:1990)

General Information

• Status: Published
• Publication Date: 16-Apr-1998
• Withdrawal Date: 28-Feb-1999
• ICS: 17.140.50 - Electroacoustics
• Technical Committee: CLC/SR 29 - Electroacoustics
• Drafting Committee: IEC/TC 29 - IEC_TC_29
• Parallel Committee: IEC/TC 29 - IEC_TC_29
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 17-Apr-1998
• Completion Date: 17-Apr-1998
• Ref Project: SIST EN 61012:2002 - Filters for the measurement of audible sound in the presence of ultrasound

Overview

EN 61012:1998 (CLC adoption of IEC 61012:1990) specifies the electrical characteristics of a U‑weighting filter for use with sound level meters that comply with IEC 651. The standard addresses measurement of audible sound in the presence of ultrasound by defining a low‑pass filter response (U‑weighting) - and the combined response when used with A‑weighting (designated AU‑weighting) - to prevent ultrasonic energy from inflating audible sound readings.

Key topics and technical requirements

• Purpose: Define a sharp low‑pass characteristic to remove ultrasonic components above ≈20 kHz so IEC 651 instruments give reproducible audible measurements.
• Designation: Filter labeled "U‑weighting"; combined A + U is "AU‑weighting". Quoted weighted levels must indicate the weighting used (U or AU).
• Nominal AU values: Example AU nominal values include –50.0 dB at 25 000 Hz, –65.4 dB at 31 500 Hz and –81.1 dB at 40 000 Hz (as given by the standard).
• Construction: Filter may be separate accessory or built into a sound level meter. If built‑in, AU switch position must be marked.
• Frequency response and poles: The standard gives the U‑weighting relative frequency response and permissible tolerances, plus filter pole locations (table of real/imaginary parts) to realize the characteristic.
• Environmental sensitivity:
  • Magnetic field test: filter tested at 80 A/m (≈1 oersted) at 50/60 Hz; orientation giving maximum indication must be stated.
  • Temperature: insertion gain/loss at 1 kHz must not vary > ±0.5 dB relative to 20 °C over the stated operating range; if it does, manufacturer must provide corrections.
  • Humidity: sensitivity shall not change by more than ±0.5 dB when RH varies from 30% to 90% (test at 40 °C, 1 kHz).
• Marking and documentation: Separate filters must be marked with standard number, manufacturer, model and serial. Manuals must state compatible meter models, input/output impedances, nominal insertion loss at 1 kHz, maximum input voltage and include test results for magnetic, temperature and humidity effects.

Applications and users

• Primary use: Measuring the audible portion of noise emitted by ultrasonic equipment (e.g., ultrasonic cleaners, welders, mechanical tools) without contamination from ultrasound.
• Who uses it:
  • Acoustical consultants and test labs performing environmental or occupational noise assessments near ultrasonic sources.
  • Manufacturers of sound level meters and filter accessories who need to design/verify U‑weighting filters to IEC/EN requirements.
  • Quality control and R&D teams evaluating ultrasonic equipment noise emissions.
• Practical benefit: Enables reproducible, Type‑1 comparable measurements of audible noise in environments where ultrasonic energy is present.

Related standards

• IEC 651 (Sound level meters) - defines A‑weighting and Type‑1 tolerances relevant when combining with U‑weighting.
• ISO 266 - preferred frequencies for measurements (referenced for nominal frequency points).

Keywords: U‑weighting, AU‑weighting, sound level meters, ultrasound, low‑pass filter, IEC 651, Type 1 tolerances, frequency response, electroacoustics.

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Filters for the measurement of audible sound in the presence of ultrasound (IEC 61012:1990)Filter für die Messung von hörbarem Schall im Beisein von UltraschallFiltres pour la mesure des sons audibles en présence d'ultrasonsFilters for the measurement of audible sound in the presence of ultrasound17.140.50ElektroakustikaElectroacousticsICS:Ta slovenski standard je istoveten z:EN 61012:1998SIST EN 61012:2002en01-september-2002SIST EN 61012:2002SLOVENSKI
STANDARD
IEC•CODE PRIXPRICE CODEGNORMECEIINTERNATIONALEIECINTERNATIONAL61012STANDARDPremière éditionFirst edition1990-01Filtres pour la mesure des sons audiblesen présence d'ultrasonsFilters for the measurement of audiblesound in the presence of ultrasound© IEC 1990 Droits de reproduction réservés — Copyright - all rights reservedAucune partie de cette publication ne peut être reproduite niNo part of this publication may be reproduced or utilized inutilisée sous quelque forme que ce soit et par aucunany form or by any means, electronic or mechanical,procédé, électronique ou mécanique, y compris la photo-including photocopying and microfilm, without permission incopie et les microfilms, sans l'accord écrit de l'éditeur.writing from the publisher.International Electrotechnical Commission3, rue de Varembé Geneva, SwitzerlandTelefax: [phone]e-mail: [e-mail] web site http: //www.iec.chCommission Electrotechnique InternationaleInternational Electrotechnical CommissionMemuyHaponHaa 3neliTpoTexHH4ecHaR HOMHCCHHPour prix, voir catalogue en vigueur•For price, see current catalogueSIST EN 61012:2002

1012 (D IE C- 3INTERNATIONAL ELECTROTECHNICAL COMMISSIONFILTERS FOR THE MEASUREMENT OF AUDIBLE SOUNDIN THE PRESENCE OF ULTRASOUNDFOREWORD1)The formal decisions or agreements of the IEC on technical matters,prepared by Technical Committees on which all the National Committeeshaving a special interest therein are represented, express, as nearlyas possible, an international consensus of opinion on the subjectsdealt with.2)They have the form of recommendations for international use and theyare accepted by the National Committees in that sense.3)In order to promote international unification, the IEC expresses thewish that all National Committees should adopt the text of the IECrecommendation for their national rules in so far as national condi-tions will permit. Any divergence between the IEC recommendation andthe corresponding national rules should, as far as possible, be clearlyindicated in the latter.4)The IEC has not laid down any procedure concerning marking as anindication of approval and has no responsibility when an item ofequipment is declared to comply with one of its recommendations.PREFACEThis standard has been prepared by IEC Technical Committee No. 29:Electroacoustics.The text of this standard is based on the following documents:Six Months'RuleReport on Voting29(C0)14129(CO)154Full information on the voting for the approval of this standard can befound in the Voting Report indicated in the above table.The following IEC publication is quoted in this standard:Publication No. 651 (1979): Sound level meters.Other publication quoted:ISO Standard 266 (1975): Acoustics-Preferredfrequenciesformeasurements.SIST EN 61012:2002

1012©IEC-5FILTERS FOR THE MEASUREMENT OF AUDIBLE SOUNDIN THE PRESENCE OF ULTRASOUNDINTRODUCTIONThe frequency response characteristics of sound level meters described inIEC 651 are not specified above 20 000 Hz. Consequently these instrumentsare not suitable for measuring the ultrasonic airborne energy emitted, forexample, by ultrasonic cleaners, mechanical tools and welders whichoperate at frequencies above 20 000 Hz. Moreover, these instruments arealso unsuitable for measuring the audio-frequency part of the soundemitted by such equipment, because the ultrasound will give rise toinflated readings if the frequency response of a particular sound levelmeter happens to extend to the operating frequency of the ultrasonicequipment.The noise which is usually of interest with ultrasonic equipment arisesfrom audible sounds produced by the ultrasonic process, for example, thecavitation noise which is audible in ultrasonic cleaners. To achieve repro-ducible measurements of the audible sound with existing sound level meterswhich comply with IEC 651, the practice is to use the A-weighting res-ponse in conjunction with a low-pass filter which has a very sharp cut-offabove 20 000 Hz. The purpose of this standard is to specify the charac-teristics of such a low-pass filter.When the filter characteristic is used with the sound level meter A-weight-ing specified in IEC 651, the resulting nominal values of the overallfrequency response fall within the scope of Type 1 tolerances.Where the measurement of the ultrasonic component frequencies is requir-ed, the practice is to measure the unweighted sound pressure level usinga microphone system which is known to have a frequency response extend-ing sufficiently, for example, to at least the operating frequency of theultrasonic equipment. A narrow band or one-third octave band filter isusually included in the measuring chain. However, this standard is notconcerned with the measurement of such components, nor with any possiblehazard from them.1. ScopeThis standard specifies the electrical characteristics of a U-weightingfilter mainly for use with sound level meters meeting the requirementsof IEC 651 for the measurement of audible sound
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