📏 Sound level meters — specifications and accuracy classes, PN-EN 61672-1

Metrology PN-EN 61672-1

Overview

THREE KINDS OF INSTRUMENT, ONE DEVICE MAY COMBINE THEM ALL. The PKN catalogue card in the POLISH version gives the distinction verbatim: "This part of IEC 61672 gives requirements for the electroacoustic performance of three kinds of sound measuring instrument: • the time-weighted sound level meter, which measures the frequency-weighted sound level with exponential time weighting; • the integrating-averaging sound level meter, which measures the frequency-weighted equivalent continuous sound level; • the integrating sound level meter, which measures the frequency-weighted sound exposure level." These are three different QUANTITIES measured, but not three mutually exclusive products — the card states plainly: "It is recognised that a single instrument may measure any or all of the three quantities specified." A modern meter usually gives all of them; the point is to know WHICH one is being read for the purposes of exposure assessment. That purpose is served by the equivalent continuous level; the time-weighted level, though also expressed in decibels, is not the quantity that exposure assessment requires.

WHY REQUIREMENTS FOR THE INSTRUMENT ARE A SEPARATE STANDARD. Noise measurement methods — such as PN-EN ISO 9612, described in a separate entry — refer to the class of instrument in a single sentence instead of repeating dozens of pages of electroacoustic requirements. As a result, a change in the requirements for meters does not require amending every method standard, and a laboratory has one place in which to check what "class 1" means.

TWO ACCURACY CLASSES AND WHAT THE DIFFERENCE BETWEEN THEM ACTUALLY IS. The Polish card states this plainly, and differently from the way it is usually repeated: "This standard specifies two accuracy classes: class 1 and class 2. In general, the requirements for class 1 and class 2 sound level meters specify the same target values, and the differences relate mainly to the acceptance limits and the range of operating temperatures. The acceptance limits specified for class 2 are equal to or greater than the corresponding values specified for class 1." A practical consequence follows that is easy to overlook: the classes do not differ in WHAT the instrument aims at, but in how far it may depart — and in WHAT TEMPERATURE it retains its declared performance. A class 2 meter used outdoors in winter may therefore fall outside its requirements for a reason that has nothing to do with acoustics. The choice of class is not a matter of diligence but of what the method requires: if a method standard or a regulation demands class 1, a class 2 instrument does not become admissible by being sound and calibrated.

EDITION AND LANGUAGE VERSIONS. The edition in force, PN-EN 61672-1:2014-03, is available BOTH in Polish and in English — both cards were retrieved on 15 September 2026 and neither has a "Date of withdrawal" row. It superseded PN-EN 61672-1:2005 together with its corrigendum Ap1:2007 — the "Supersedes" field lists both documents, so the replacement covered the standard together with its corrigendum. We note the availability of the Polish version because with some standards described in this knowledge base it is the other way round (e.g. PN-EN 482, PN-EN 933-2, PN-EN 12390-4): newer editions cease to be translated.

RELATION TO CALIBRATION. Conformity with the requirements of the standard is a property of the TYPE of instrument, confirmed by testing, whereas the soundness of an individual item is the subject of calibration. A class 1 meter after a fall, or after years of service, is still "class 1" in the sense of its type, but its errors may fall outside the permissible limits. A check with an acoustic calibrator before and after a measurement does not replace calibration — it detects a change of sensitivity at one point, not across the whole band.

WHAT WE DO NOT GIVE. We do not have the text of the standard — PKN supplies it for a fee (TC 105, ICS 17.140.50). We therefore DO NOT GIVE the values of the tolerances for any class, the frequency ranges or the time constants. Such values are sometimes quoted from memory or from manufacturers’ materials; an entry presenting them as the content of the standard would claim more than we have verified.

Method principle

A sound level meter converts acoustic pressure into an indication in decibels, applying along the way frequency weighting filters and time averaging. The standard specifies how far the actual characteristic of an instrument may depart from the reference characteristic — separately for each accuracy class and separately for the three kinds of instrument, since each of them gives a different quantity: the time-weighted level, the equivalent continuous level or the integrated level.

Applications

• Selecting an instrument for noise measurements at workplaces and in the environment
• Checking whether an available meter corresponds to the class required by a method standard or a regulation
• Purchasing specifications for measuring equipment in an acoustics laboratory
• Reviewing another laboratory's report: whether the kind and class of instrument match the quantity measured

Key parameters

Standard

Standard number

PN-EN 61672-1:2014-03 (dostępna w wersji POLSKIEJ i angielskiej; wprowadza EN 61672-1:2013 [IDT] oraz IEC 61672-1:2013 [IDT])

Title (PL)

Elektroakustyka -- Mierniki poziomu dźwięku -- Część 1: Wymagania

Title (EN)

Electroacoustics — Sound level meters — Part 1: Specifications

Step-by-step procedure

1. Establish the quantity to be measured

   Decide whether what is needed is the time-weighted level, the equivalent continuous level or the sound exposure level. One instrument may give all three — make sure WHICH one you are reading.

2. Establish the required class

   Check in the method standard or the regulation which class of instrument is required. A lower class does not become admissible through the soundness of the item.

3. Verify type conformity

   Conformity with the requirements of this standard is declared by the manufacturer on the basis of type testing — check that the declaration covers the correct edition of the standard.

4. Calibrate the item

   A current calibration certificate. The declaration of class concerns the type, not the condition of a particular instrument after years of service.

5. Check with a calibrator

   Before and after the series of measurements. A discrepancy between the initial and final check invalidates the series.

6. Record in the report

   Give the kind and class of instrument, the number of the calibration certificate and the full designation of the standard with its year.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Measurement is carried out in noise — the same hearing protection measures apply as to the workers at the workplace being measured
• TECHNICAL NOTE: reading the time-weighted level instead of the equivalent continuous level yields a quantity that exposure assessment does not provide for — a modern meter gives both, and it is the choice of reading that decides, not the instrument itself
• TECHNICAL NOTE: a check with a calibrator confirms sensitivity at a single point of the band, not conformity with the requirements of the class

Frequently asked questions