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How we calibrate at Norsonic Calibration Laboratory | ISO 17025

Norsonic — Mon, 15 Jun 2026 08:37:58 GMT

Before sending equipment for calibration

Contact the laboratory to optimize the time schedule for both you and us.
Wait for an email quotation from the laboratory before sending the equipment. It will be sent quickly.

When submitting equipment for calibration remember

Print and attach the email quotation you received from us. It contains quotation number and information about your equipment. Then you get the right type of calibration, the right price, and the fastest possible service.
Be careful to inform us if the return address or invoice address is different from the sender address.
If you would like us to make adjustments and maintenance of the equipment while it is at Norsonic, then please contact us about this. If there are known defects in your equipment, we can have it repaired at the same time.
Send your instruction manuals with the equipment. (Not necessary for Norsonic equipment.) Many manufacturers change the specifications of their products during the life cycle, and we would like to measure your equipment correctly. If we do not have the necessary information, we must contact the supplier. If information is not available, we cannot calibrate your equipment. Then we cannot guarantee that we keep the agreed delivery time, and an additionally fee may be added. Contact your Customer Adviser to make sure we have the right information about your equipment.
Make sure to send the equipment using a service provider you trust. Preferably get a tracking number of the parcel so both you and we can always know where it is. You can also personally bring your instrumentation to NCL if that is suitable for you. Our opening hours are usually workdays from 08:00 to 15:00. Please call us upfront to be sure.

Calibration of sound calibrators

Sound calibrators are calibrated using a reference microphone. This is done according to an international standard, IEC 60942, which ensures that your certificate contains the values for level, frequency and distortion with very good accuracy.

Calibrators are divided into two accuracy classes. Class 1 is intended for control of precision measuring equipment, while class 2 is intended for control of other sound measuring equipment. The class name must be on the calibrator. Our measurement procedure is called L244-02.

Especially for Norsonic calibrators: If a calibrator comes in out of specifications, the customer will of course be notified immediately. If during the calibration it turns out that only small adjustments are needed, we want to provide the service that the calibrator is adjusted as close to nominal values as is practically possible. This later gives the customer a better control of their sound measurement equipment. The customer can notify the customer supervisor that he does not want this adjustment.

Statement of conformance
For a type approved sound calibrator, the standard (IEC 60942) allows to issue a certificate which includes a “statement of conformance”. This statement is based on the type approval of the object type, and the results of the actual measurements. The statement will tell if the measurement object is working according to the requirements in the standard, or not.

If your type of sound calibrator is type approved, NCL usually includes a statement of conformance.
Please contact the Customer Adviser if you do not want a statement of conformance included on your certificate.

Calibration of pistonphones

A pistonphone is a special version of a mechanical laboratory reference calibrator. The calibration of reference pistonphones is different the calibration of other sound calibrators. This is to obtain an even better precision in the results. Pistonphones are also described in IEC 60942 standard. Our calibration procedure is called L244-40.

Calibration of sound level meters

Calibration of sound level meters is an extensive process. It consists of both acoustic tests and simulation of sound with electrical signals. The sound level meter calibration follows the standard IEC 61672-3. Our procedure is called L244-07. Both frequency response, level linearity and the properties of measuring pulse-shaped signals are tested. Microphone and preamplifier are included in the calibration. The standard has two accuracy classes. Class 1 is used for precision sound level meters and class 2 is for general sound meters. The class is indicated on the sound meter.

Statement of conformance
For a type approved sound level meter, the standard (IEC 61672) allows to issue a certificate which includes a “statement of conformance”. This statement is based on the type approval of the object type, and the results of the actual measurements. The statement will tell if the measurement object is working according to the standard, or not.

NCL usually includes a statement of conformance on the certificate if your type of sound level meter is type approved.
Please contact the Customer Adviser if you do not want this statement to be included on your certificate.

Calibration of microphones and microphone preamplifiers

Some customers want to have their microphones and preamplifiers calibrated separately. These calibrations are more detailed in frequency response than those required for regular sound meter calibration. Our procedures for microphones and preamps are called L244-03 and L244-10 respectively. The standard procedure is to measure absolute sensitivity with a reference calibrator and frequency response using electrostatic actuator.

NCL can also calibrate your microphones and microphone preamplifier combinations (microphone set) in an anechoic chamber. Our free-field procedure L244-12 ensures high accuracy and good resolution of these measurements. The standard for calibrating microphones is called IEC 61094.

Calibration of accelerometers and vibration calibrators

Vibration and sound are often closely related. Many customers have gradually acquired accelerometers for connection to the sound meter. We calibrate the accelerometer’s sensitivity and frequency response by comparison with a reference accelerometer in accordance with ISO 16063-21.

We can also calibrate vibration calibrators. The level, frequency and distortion of the calibrator are controlled with good accuracy. Our procedure is called L244-17.

Calibration of tapping machines

Tapping machines are used to generate simulated step noise. The machine and the use of it is described in ISO 10140-5 and ISO 16283-2. Our calibration procedure is called L244-15. Before calibration, the fall height of the hammers is adjusted.

We also perform cleaning and lubrication maintenance of the machinery prior to the calibration to ensure proper results and a long faultless time of operation.

Statement of conformance
When all measurements are performed and the results (without uncertainty) are within the required tolerance limits, we usually state that the tapping machine is “according to the standards”. This statement appears on your certificate. If you for one or another reason don’t want it there, please inform us and we act accordingly.

Calibration of reference sound sources

The calibration of reference sound sources is described in ISO 6926. Our calibration procedure is L244-16. The calibration is performed in a very large hall simulating free field conditions over a reflecting plane. Since the facilities are also used for other purposes, there can be some longer turnaround time than normal. Be sure to schedule the calibration with your customer advisor to avoid unnecessary waiting time.

Statement of conformance
When the measurement results (without uncertainty) show that the reference sound source is within the requirements of the standard, we usually state that it “conforms to the standard”. A statement appears on your certificate. If you for one or another reason don’t want it there, please inform us and we act accordingly.

Calibration and tests of other equipment

At Norsonic Calibration Laboratory, we have extensive experience in calibrating and testing a wide variety of equipment, both what Norsonic has made and what is made by other manufacturers. Feel free to contact us so we can help you.

We are constantly working on improving our quality and ensure that our calibration procedures are up to date, and that the measurement equipment are regularly calibrated. We
have a continuous focus on education and our calibration technicians are well qualified for the work.

A list of our accredited services can be found at: Norsk Akkreditering.

Norsonic Calibration Laboratory

Why calibrate? Norsonic explain how and why | Norsonic

Norsonic — Mon, 15 Jun 2026 08:37:57 GMT

Checking a measurement system with a sound calibrator

The process of checking a measurement system with a sound calibrator is referred to as calibration in standards such as ISO 1996-2 and the ISO 16283 series. The check is done to ensure that the measurement system, for example a sound level meter, is working as specified. Some of the application standards describing measurement methods require calibration at the beginning and at the end of each measurement session. In this way, the operator can ensure that all data is correctly acquired and that nothing has changed during the measurement session.

Performing and documenting calibration is always important, especially if legal actions are to be taken based on the measurement results.

The starting point of the check is applying a calibrated sound calibrator, generating a known sound pressure level within given uncertainties, to the sound level meter or measurement system. The use of calibrators dates to those days when it was easier to design a stable calibrator than a stable sound level meter. Fortunately, this is no longer the case as sound level meters are as stable as calibrators. However, microphones are delicate devices which can be easily subject to damage unless great care is taken.

NoiseTag is an AI-based source classification in NorCloud | Norsonic

Jorge Paez Rodriguez — Mon, 15 Jun 2026 08:37:56 GMT

Noise source classification in environmental monitoring

Environmental noise measurements rarely contain only the sound of the activity under study. Traffic, nearby industry, weather-related noise and other sources are often captured together with the target noise.

Identifying which events belong to the activity — and which ones do not — is one of the most time-consuming and subjective parts of noise analysis, especially in long-term or unattended monitoring projects.

NoiseTag addresses this challenge by automatically classifying noise sources during environmental monitoring. Integrated into NorCloud, NoiseTag identifies which events are relevant to the activity being studied and which are not. Irrelevant noise—sounds that are not part of the activity—can therefore be excluded from the analysis. By reducing the need for manual review, NoiseTag shortens analysis time and improves the consistency and accuracy of the results.

Swept Sine Method for Reverberation Time Measurement

Jorge Paez Rodriguez — Mon, 15 Jun 2026 08:37:55 GMT

What is the swept sine method?

The swept sine method, also known as swept sine excitation, is one of the procedures accepted for measuring reverberation time (RT) in room acoustics and building acoustics, as described in the ISO 3382 series of standards.

Impact Sound Insulation Measurements

Jorge Paez Rodriguez — Mon, 15 Jun 2026 08:37:54 GMT

What is impact sound insulation?

Impact sound insulation describes the ability of a floor or building structure to reduce the transmission of structure-borne sound generated by mechanical excitation.

Speech Intelligibility Measurement Using STI and STIPA

Jorge Paez Rodriguez — Mon, 15 Jun 2026 08:37:53 GMT

What Is Speech Intelligibility?

Speech intelligibility describes how easily a spoken message can be understood by listeners within a given space.
Speech understanding does not depend solely on sound level.

Factors such as reverberation, background noise, the distance between the source and the listener, and the performance of the sound system can significantly affect message clarity.

In environments such as classrooms, auditoriums, railway stations, airports, or voice evacuation systems, insufficient speech intelligibility can hinder communication and reduce the effectiveness of transmitted messages.

Impulsive Method for Reverberation Time Measurement

Jorge Paez Rodriguez — Mon, 15 Jun 2026 08:37:46 GMT

What is the impulsive method?

The impulsive method is one of the procedures described in the ISO 3382 series of standards for measuring reverberation time (RT) in rooms.

Basic Information about General Acoustics | Norsonic

Norsonic — Mon, 15 Jun 2026 08:37:46 GMT

How does sound travel?

Understanding the fundamental principles of sound is essential in building acoustics and environmental acoustics:

Interrupted Noise Method for Reverberation Time Measurement

Jorge Paez Rodriguez — Mon, 15 Jun 2026 08:37:16 GMT

What is the interrupted noise method?

The interrupted noise method is one of the classical procedures described in the ISO 3382 series of standards for measuring reverberation time in rooms.

Understanding sound in rooms and sound insulation

Jorge Paez Rodriguez — Mon, 15 Jun 2026 08:37:15 GMT

How does sound behave in a room?

Assume that we place a sound level meter at a fixed position in a room and then start a sound source. This source could be a machine, or a combination of a noise generator, power amplifier, and loudspeaker.
At first, one might expect the sound pressure level in the room to keep increasing as long as the sound source continues to emit energy. In reality, this does not happen. Instead, the sound level rises and then stabilizes at a certain value.