Why This Information?

The amount of noise a machine emits is no longer just a matter of comfort; it's a condition for the product to enter the European market. Under the EU Machinery Regulation (EU) 2023/1230, declaring the noise emission values of machines has become an integral part of the CE technical file. For Turkish machinery exporters, this means characterizing the acoustic behavior of the product using defined and repeatable methods.

This page is an informational text designed to conceptually explain the three fundamental standards used in determining the sound power level (noise emission) of machinery and equipment: ISO 3744, ISO 9614, and ISO 11202. The aim is not to provide precise numerical limits, but rather to contribute to a correct understanding of the concepts, methods, and declaration obligations.

The Critical Concept: The Difference Between Sound Power and Sound Pressure

The most common confusion regarding noise emissions is the mixing of sound power and sound pressure. These are two different physical quantities, and confusing them leads to misrepresentations.

Sound power is an inherent characteristic of the source itself: the total acoustic energy the machine radiates in all directions per unit time. It is independent of location, distance, or medium; it is an intrinsic quantity defining the source and is expressed as sound power level (LW or, in its A-weighted form, LWA).

Sound pressure is a property of space at a point: it varies depending on distance, the reflectivity of the medium, obstacles, and the measurement location. What a person actually 'hears' at a particular point is sound pressure, and it is expressed as emission sound pressure level (LpA).

The practical result is this: the same machine, even with the same sound power, may give a low sound pressure reading at a distance in an open field, and a higher reading in a workshop with reverberation. Therefore, while sound power levels derived under standard conditions are used for objective comparison and declaration of products, the acoustic environment to which the operator is exposed is defined by the workplace emission sound pressure.

• Sound power (LWA): total energy emitted by the source; location independent; a key metric for product comparison and declaration.
• Sound pressure (LpA): the magnitude of a field at a specific point; dependent on distance and environment; the level experienced by the operator.
• Sound power is not measured directly; according to ISO 3744 and ISO 9614, it is calculated from measurements of sound pressure or sound intensity.

This measurement differs from occupational safety and health (OSH) environmental exposure measurement.

An important distinction: the measurements discussed on this page are characterizations of the machine's noise emissions — that is, to determine the acoustic properties of the product for the manufacturer's declaration. This serves a different purpose than workplace noise exposure measurements within the scope of occupational health and safety (OHS).

Occupational safety and health (OSH) exposure measurements typically assess the daily noise exposure level (e.g., LEX,8h) an employee experiences during a shift; this is aimed at protecting an employee in a given workplace and encompasses multiple sources, environments, and durations. Machine emission standards (ISO 3744, ISO 9614, ISO 11202), on the other hand, isolate the emission of a single machine under defined operating conditions, producing a comparable value for the product.

In short: emission characterization answers the question 'what is this machine emitting?', while exposure measurement answers 'how much of it is this worker exposed to?'. The two fields complement each other, but their methods and purposes are different.

ISO 3744 — Determination of Sound Power from Sound Pressure (Engineering Grade)

ISO 3744 is an engineering-grade (class 2/accuracy) method for determining the sound power levels of noise sources using sound pressure. The full title of the standard refers to the conditions of 'essentially free space over a reflective plane'.

The basic principle of the method is to define a measuring surface (envelope surface) surrounding the machine and to measure sound pressure levels at designated microphone locations on this surface. Using the measured sound pressure values and the area of the measuring surface, the sound power level of the source is calculated. The measuring surface is usually chosen in the form of a hemisphere or rectangular prism (box) surrounding the machine.

A suitable measurement environment is one that approximately provides acoustic free space near one or more reflective planes (e.g., a qualified quasi-anechoic chamber or a suitable open space). For non-ideal environments, the standard includes procedures for applying environmental corrections. The method is applicable to continuous, discontinuous, and fluctuating noise types. ISO 3744 is frequently referred to as the basic noise emission standard under EU Machinery legislation.

ISO 9614 — Sound Power Determination by Intensity Method

The ISO 9614 series determines sound power level from sound intensity measurements. Unlike sound pressure methods, it directly measures the sound intensity component perpendicular to the measurement surface; this requires a special sound intensity probe (with two microphones).

A significant advantage of the sound intensity method is its relative resistance to background noise and reflections, and its ability to allow in situ (on-site) measurements in many cases. This makes it a valuable option for sites where large or immovable machines are used and an ideal acoustic environment cannot be achieved.

The series includes different procedures: ISO 9614-1 defines measurement at discrete points, ISO 9614-2 measurement by scanning, and ISO 9614-3 precision measurement by scanning. The validity of the measurement is evaluated using field indicators and criteria defined in the standard; these indicators are a measure of whether the result is reliable.

ISO 11202 — Workplace Emission Sound Pressure Level

ISO 11202 is intended for determining the noise emitted by machinery and equipment in situ conditions, as the emission sound pressure level (LpA) at a workplace (operator position) and other specified locations. This standard targets the emission sound pressure at the operator's position, not the sound power.

The work area is the location occupied by the operator; it may be in an open area, in the room where the machine is operating, in a cabinet attached to the machine, or in a separate enclosure from the machine. Emission sound pressure levels are determined as A-weighted (dB(A)); levels in frequency bands and C-weighted peak values can also be determined if required.

The standard provides methods for determining approximate environmental correction, subject to a defined upper limit, to be applied to values measured in less than ideal environments. When this correction limit is exceeded, a more controlled environment or a different method may be required. ISO 11202, along with sound power standards (ISO 3744 / ISO 9614), produces operator position information that complements the machine's noise declaration.

Measurement Environment, Accuracy Classes, and A-Weighted Level

The reliability of noise emission measurements depends largely on the measurement environment and the accuracy class of the chosen method. Standards generally define methods at laboratory (precision/class 1), engineering (engineering/class 2), and survey (survey/class 3) levels; ISO 3744 is an engineering-class method. Higher accuracy requires a more controlled environment and stricter measurement conditions.

Environmental requirements include sufficient free-field conditions, sufficiently low background noise relative to the measured signal, and—in the relevant method—the environmental correction values remaining within defined limits. Failure to meet these conditions may render the measurement invalid or increase its uncertainty.

Emission values are typically expressed as A-weighted levels (dB(A)). A-weighting is a frequency weighting that approximately models the sensitivity of the human ear to different frequencies; thus, a single number better correlates with perceived noise. Since precise numerical thresholds vary depending on the machine type, operating conditions, and method applied, no specific dB limits are given on this page; the final assessment should be made by a qualified engineer.

• Accuracy classes: laboratory (precision), engineering, survey.
• Environmental conditions: sufficiently free space, low background noise, limited ambient correction.
• A-weighted level dB(A): a single numerical indicator weighted according to human hearing.

EU Machinery Regulation (EU) 2023/1230 and Noise Emission Declaration

EU Machinery Regulation (EU) 2023/1230 strengthens the requirements for noise reduction at the source and the explicit declaration of noise emission levels of machinery as essential health and safety requirements. The regulation replaces the previous Machinery Directive 2006/42/EC.

In practice, the manufacturer declares the noise emission values of the machine in the operating instructions and technical file. This declaration usually includes the emission sound pressure level (LpA) at the workplace and—when certain thresholds are exceeded—the sound power level (LWA) emitted by the machine. Basic noise emission standards such as ISO 3744 are used to determine the sound power level; emission sound pressure standards such as ISO 11202 are used for the operator's position.

For Turkish machinery exporters, this requires that the acoustic characterization of the product be carried out using defined, repeatable, and traceable methods, and that the results be accurately recorded in the CE technical file. Accurate reporting of declared values, measurement conditions, and uncertainties is critical for ensuring compliance and sustainable access to the market.

Which sectors? All areas involved in machinery manufacturing and export are included: metalworking machines, plastics and injection molding machines, food and packaging machinery, textile machinery, compressors and pumps, generators, agricultural and construction machinery, HVAC equipment, and electrical/electronic equipment manufacturers. For certain types of equipment used outdoors, relevant outdoor noise regulations must also be considered.

Information Note

This content is for informational purposes only and is subject to the technical assessment of a qualified engineer. The measurement method to be applied to a machine (ISO 3744, ISO 9614 or ISO 11202), the relevant accuracy class, the quantities to be declared and the measurement uncertainty must be determined by a qualified engineer according to the type of machine, the operating conditions and the applicable legislation.

AES is NOT a Notified Body or certification body. AES is a Type A inspection body accredited by TÜRKAK only under the scope of '6.1 Electrical Installations'. This page does not imply accreditation, certification, or CE marking; it provides general technical information.

Related Services

• Machine CE Conformity and Risk Assessment
• Occupational Health and Safety Environmental Measurements

Frequently Asked Questions

Are sound power level and sound pressure level the same thing?

No. Sound power (LWA) is the total acoustic energy emitted by the source and is location-independent; it is used to compare and describe the machine. Sound pressure (LpA), on the other hand, is the magnitude at a specific point, varying depending on distance and environment, and describes the level actually heard by the operator. Sound power is not measured directly; it is calculated from sound pressure or sound intensity measurements under standard conditions.

What is the difference between ISO 3744, ISO 9614, and ISO 11202?

ISO 3744 is an engineering-grade method that determines sound power levels by measuring sound pressure on an envelope surface surrounding the machine. ISO 9614 determines sound power from sound intensity measurements and is generally more suitable for in situ conditions. ISO 11202 determines the emission sound pressure level (LpA) at the operator's workspace, not sound power. Together, the three complete the machine's noise emission profile.

Are these measurements the same as workplace noise exposure (OHS) measurements?

No. These standards characterize the noise emission of the machine, that is, they determine the acoustic properties of the product for declaration. Exposure measurements within the scope of occupational health and safety, on the other hand, assess the noise level to which an employee is exposed during a shift (e.g., LEX,8h) and are aimed at protecting the employee in the current workplace. Their purposes and methods are different; they complement each other.

What does the EU Machinery Regulation (EU) 2023/1230 require regarding noise?

The regulation requires noise reduction at the source and clear declaration of the machine's noise emission values. The manufacturer declares the emission sound pressure level at the workplace and the sound power level when certain thresholds are exceeded in the operating instructions and the CE technical file. Basic emission standards such as ISO 3744 are used as a basis for determining sound power.

Which sectors are required to make this declaration?

This includes all manufacturers and exporters supplying machinery or equipment to the European market: metalworking, plastics, food and packaging, textiles, compressor and pump, generator, agricultural and construction machinery, HVAC and electrical/electronic equipment manufacturers, etc. The applicable method and scope of declaration vary according to the type of machinery and are determined by the authorized engineer.

Does AES provide certification or CE marking related to these measurements?

No. AES is not a Notified Body or certification body, and this content is for informational purposes only. AES is a Type A inspection body accredited by TÜRKAK only under the scope of '6.1 Electrical Installations'. The assessments on this page are within the framework of authorized engineer technical assessments.