Many industrial processes emit infrasound or ultrasound (wind turbines, heat pumps, ultrasonic cleaning systems, etc.). However, the mechanism for perceiving sounds outside the audible range is not currently well understood. Manufacturers and operators of installations that emit this type of sound need noise emission regulations to be well-founded and not unnecessarily restrictive: it is therefore necessary to define rational, evidence-based criteria to prevent the risks associated with these sounds.

In order to define criteria for limiting exposure and protecting the population, it is necessary to have a metrological infrastructure with reference standards, calibration methods and appropriate measuring equipment to quantify the harmful effects of ultrasound and infrasound.

OBJECTIVES

Understanding human perception of non-audible sounds.

Define the metrological structure necessary to apply safety criteria based on sound perception thresholds.

Provide traceability to national standards through the development of a universal ear simulator to model human ear impedance for both adults and children.

SUMMARY AND RESULTS

This European project comprised five technical work packages:

1 - Measurement technology for determination of brain responses to non-audible sound

2 - Measurement requirements for non-audible sound

3 - Brain response thresholds and hearing thresholds for non-audible sound

4 - Design of a wideband universal ear simulator

5 - Test and validation of the universal ear simulator and determination of reference data

LNE participated in the fourth work package, which focused on developing a tool to simulate the acoustic behaviour of the ears of newborns, children and adults. The aim was to be able to calibrate audiometers, adjust hearing aids (prostheses) and detect hearing loss from an early age.

Initially, the work consisted of establishing specifications in line with user needs, developing a design methodology to highlight the key parameters, and gathering the information necessary for this design through an extensive literature review. Based on the results of the literature review, five age groups were established: newborns, 1-3 months, 3-6 months, 3-24 months, 2-7 years, and adults.

Vue en coupe du simulateur d'oreille pour nouveaux nés.
Cross-sectional view of the newborn ear simulator. 𝘛𝘩𝘦 𝘶𝘱𝘱𝘦𝘳 𝘰𝘱𝘦𝘯𝘪𝘯𝘨 𝘳𝘦𝘱𝘳𝘦𝘴𝘦𝘯𝘵𝘴 𝘵𝘩𝘦 𝘳𝘦𝘧𝘦𝘳𝘦𝘯𝘤𝘦 𝘱𝘭𝘢𝘯𝘦 𝘰𝘧 𝘵𝘩𝘦 𝘦𝘢𝘳 𝘤𝘢𝘯𝘢𝘭, 𝘢𝘯𝘥 𝘢 ¼″ 𝘮𝘪𝘤𝘳𝘰𝘱𝘩𝘰𝘯𝘦 𝘪𝘴 𝘯𝘰𝘳𝘮𝘢𝘭𝘭𝘺 𝘱𝘰𝘴𝘪𝘵𝘪𝘰𝘯𝘦𝘥 𝘰𝘯 𝘵𝘩𝘦 𝘶𝘯𝘥𝘦𝘳𝘴𝘪𝘥𝘦 𝘵𝘰 𝘮𝘦𝘢𝘴𝘶𝘳𝘦 𝘢𝘤𝘰𝘶𝘴𝘵𝘪𝘤 𝘱𝘳𝘦𝘴𝘴𝘶𝘳𝘦 𝘴𝘪𝘨𝘯𝘢𝘭𝘴, 𝘴𝘪𝘮𝘶𝘭𝘢𝘵𝘪𝘯𝘨 𝘵𝘩𝘦 𝘦𝘢𝘳𝘥𝘳𝘶𝘮.

Following completion of this initial task, ear simulators were designed for each of the five age groups. This task was accomplished using both analytical and numerical acoustic modelling.

For cost reasons, only the prototype for the newborn group was manufactured. The prototypes were qualified in parallel by four national metrology laboratories, including the LNE. This qualification mainly consisted of measuring the acoustic transfer impedance of the simulator (ratio between the input flow and the acoustic pressure on the simulator's microphone) and comparing it with that calculated by the LNE during the design phase. The results of this qualification show measurements that are well aligned with the theoretical curve over a wide frequency range, except at high frequencies (above 6 kHz).

 

Prototypes de simulateurs d'oreille néonatal
Prototypes of neonatal ear simulators (photo from the Ears project)

PUBLICATIONS ET COMMUNICATIONS

BARHAM R., OLSEN E.S., RODRIGUES D., BARRERA-FIGUEROA S., SADIKOGLU E. and KARABÖCE B., “The calibration of a prototype occluded ear simulator designed for neonatal hearing assessment applications”, The Journal of the Acoustical Society of America, 2016, 140, 2, DOI: 10.1121/1.4960517.

RODRIGUES D., LAVERGNE T., OLSEN E.S., FEDTKE T., BARHAM R. and DUROCHER J., “Methodology of Designing an Occluded Ear Simulator”, Acta Acustica, 2015, 101, 5, DOI: 10.3813/AAA.918895.

RODRIGUES D., LAVERGNE T., OLSEN E.S., BARHAM R., FEDTKE T. and DUROCHER J., “Design of a new ear simulator”, Inter-Noise 2015, San Francisco, United States, 9-12 August 2015.

RODRIGUES D., LAVERGNE T., FEDKE T., SANDERMANN OLSEN E., BARHAM R. and DUROCHER J.-., “Methodology of designing an ear simulator”, Internoise 2013, Innsbruck, Austria, 15-18 September 2013.

LAVERGNE T., RODRIGUES D., NEIMANNS V., SANDERMANN OLSEN E. and BARHAM R., “Universal ear simulator: Specifications and artificial ear canal design”, Internoise 2013, Innsbruck, Austria, 15-18 September 2013.

PARTNERS

National metrology institutes:

  • PTB (project coordinator),
  • NPL,
  • LNE,
  • DFM,
  • Tubitak UME,
  • BKSV-DPLA.

The noise produced by machinery or equipment is a technical characteristic generally expressed in terms of acoustic power (power level in dB relative to a reference acoustic power of 10-12 watts). When this project was started, the experimental determination of power was based on acoustic pressure measurements taken using microphones. The acoustic power was then evaluated by calculation, under various assumptions and conditions that were not perfectly met. As a result, the connection to the international system of units was achieved by linking pressure levels through microphone sensitivity measurements. This resulted in a ‘true’ assessment of acoustic power being marred by all kinds of biases, uncorrected influencing factors and methodological errors. The situation was made even more complex by the fact that some of the acoustic power measurements used a method of comparison with reference sound sources, which were themselves calibrated using the pressure method and were quite sensitive to environmental conditions.

The aim of this project was therefore to develop and characterise a primary standard sound source and then disseminate it via transfer standards (which are the sound sources that were previously used as references). The application to machine noise was then to be carried out by developing new procedures for measuring sound power in different environments and evaluating the associated measurement uncertainties.

OBJECTIVES

Develop a reference sound source whose acoustic power can be calculated from measurements of vibration velocity, dimensions, and environmental air properties, with an uncertainty of 0.5 dB.

Measure the acoustic power of this reference sound source using sound intensity instruments calibrated in accordance with IEC 61043 and explain any deviation from the expected behaviour. This is necessary to distinguish the phase shift between the speed of sound and the acoustic pressure on the surrounding surface.

Develop methods for calibrating non-calculable sound sources by comparison with the reference sound source. The focus will be primarily on broadband sources, which generate sounds aerodynamically. Another aspect addressed is the development of a new concept for tonal sound sources.

Develop qualification procedures for measuring devices, analyse uncertainties associated with determining sound power in practice, and develop a substitute method using sound intensity for machine noise.

SUMMARY AND RESULTS

Exemple de source sonore de référence utilisée au LNE
Example of a reference sound source used as a transfer standard at the LNE.

Primary standard sound source

The objective of this part was to produce a primary standard for the acoustic watt in air. This is based on a baffled vibrating solid body (piston). The sound power of this device can be determined from the vibration speed of the body's surface, measured by laser interferometry, and several other variables such as static pressure and temperature. The various candidates for primary sources are based on two techniques: an electrodynamic pot or a loudspeaker ‘motor’. The electrodynamic pot is a vibration source commonly used in laboratories. It drives the movement of a metal piston. The latter must have as much overall movement as possible and as little parasitic movement as possible, due to its lack of rigidity and its natural modes/frequencies at high frequencies. The other method involves using a loudspeaker ‘motor’ that drives a lighter piston. Guiding the piston in a unidirectional and free movement is difficult to achieve. In this project, primary sources were developed by PTB, SP, INRiM and TUBITAK UME.

Diffusion of the ‘acoustic watt’ unit

The objective of this part was to develop a system for disseminating the acoustic watt unit using appropriate transfer standards. This made it possible to examine whether existing aerodynamic reference sound sources could be used as transfer standards. The answer was positive, provided that their sensitivity to atmospheric conditions was known. The uncertainty of the sound power emitted by the transfer standards was determined. The objective was for this uncertainty to be only slightly greater than the uncertainty of the primary standard. The LNE developed a scanning apparatus for automated measurement of acoustic power by measuring the acoustic pressure on a 2 m radius hemisphere centred on a reference source flush with the ground.

At LNE, unlike other partners, a single microphone is used, moved to each position by an automatic device and controlled by software that manages both the scanning device and the acoustic signal analyser acquisition. The first movement is made along a rail describing a 90° vertical arc. The second movement consists of moving this arc around a vertical axis to cover the entire hemispherical surface. A third movement moves the microphone along a 1 cm radius to evaluate the intensity in two stages.

"Scanning apparatus" du LNE : vue d'ensemble et détail de la tête de mesure
LNE scanning apparatus: overview (left) and detail of the measuring head (right)

Project website:

http://www.ptb.de/emrp/sib56-home.html

PUBLICATIONS AND COMMUNICATIONS

BREZAS S., CELLARD P., ANDERSSON H., GUGLIELMONE C. and KIRBAS C., “Dissemination of the unit Watt in airborne sound: aerodynamic reference sound sources as transfer standards”, INTER-NOISE 2016, Hamburg, Germany, 21-24 August 2016.

CELLARD P., ANDERSSON H., BREZAS S. and WITTSTOCK S., “Automatic sound field sampling mechanisms to disseminate the unit watt in airborne sound”, INTER-NOISE 2016, Hamburg, Germany, 21-24 August 2016.

Partners

The work was carried out as part of the European project JRP SIB56, which included the following national metrology laboratories:

  • PTB (DE),
  • INRIM (IT),
  • LNE (FR),
  • SP (SE),
  • TUBITAK (TK).

The European project, coordinated by the SFI-Davos (Switzerland), aims to develop methods for measuring direct, diffuse and global solar spectral irradiance between 290 nm and 400 nm with an uncertainty of 1% to 2% and new instruments for rapid measurement of spectral irradiance (UV to TF spectroradiometers) to take into account rapid variations in atmospheric conditions (measurement duration less than 10 s and repetition time less than 1 min).

Objectives

Improved measurements of UV radiation from the solar spectrum reaching the ground

Estimation of uncertainties of matrix spectroradiometers

Development of a photodiode array spectroradiometer optimized for spectrum measurement between 290 nm and 400 nm and with minimization of stray light

Summary

Find here the detailled description of the project:

http://projects.pmodwrc.ch/env03/

Publications and communications

DUBARD J. et  ETIENNE R., “Monte Carlo uncertainty evaluation of UV solar spectral irradiance measurements using array spectroradiometer”, 7th Workshop on Ultraviolet radiation measurements (UVNET), Davos, Suisse, 27-28 août 2013.

DUBARD J., VALIN T., ETIENNE R. et EBRARD G., “EMRP-ENV03: Traceability for surface  spectral solar ultraviolet radiation”, 16e Congrès International de Métrologie, Paris, France, 7-10 octobre 2013, DOI: 10.1051/METROLOGY/201318001.

Partners

JRP-ENV03 partners:

  • SFI Davos (Switzerland),
  • EJPD/METAS (Switzerland),
  • PTB (Germany),
  • VSL (Netherlands),
  • CMI (Czech Republic),
  • LNE (France),
  • INRIM (Italy),
  • Aalto (Finland),
  • CMS (Austria),
  • Kipp&Zonen (Netherlands),
  • IMU (Austria).

At micro and nano-scale liquid flow rates, calibration is critical, especially for applications such as volumetric dosing and drug delivery. In particular, for drugs with a very short half-life (in the order of one minute), or for drugs that require a very low blood concentration for toxicity reasons, such as vasoactive or anaesthetic drugs, the exact amount of volume administered as well as the stability of the flow rate are crucial.

OBJECTIVES

Establishment of an infrastructure for calibration of drug delivery systems for flows up to 10-100 nl/min

Development of transfer standards for on-site calibration of drug delivery equipment

Performance evaluation of drug delivery devices, dependence on operating conditions and clinical characteristics

Provision of a good practice guide for drug dispensing and improved calibration services for drug delivery devices

SUMMARY AND RESULTS

Until 2012, however, metrological traceability for these very low flow ranges was only validated in Europe from 16 l/min upwards.

 

Banc de microdébitmétrie liquide du Cetiat
CETIAT microflow reference

The national metrology laboratories LNE-CETIAT, DTI, IPQ, METAS, and VSL developed primary calibration methods covering a range of liquid flow rates from 10 l/h to 10 nl/min as part of the European metrology research project “HLT07 Metrology for Drug Delivery – MeDD.” These national references have been validated by comparing the measurement results obtained with a Coriolis mass flow meter and a syringe pump (see figure opposite). These results have led to the submission of new calibration possibilities (CMC, Calibration and Measurement Capabilities) that are unprecedented for these flow ranges.

 

Comparison de mesures de débits avec un pousse-seringue
Validation of developed national references (comparison of measurements with a syringe pump)

The influence of several physical parameters such as temperature, back pressure, viscosity, and flow pulsations was studied. It was thus demonstrated that Coriolis mass flow meters are less sensitive to the physical parameters studied and therefore constitute transfer standard flow meters suitable for establishing metrological traceability for medical devices.

 

With regard to infusion devices, several characteristics were tested: start-up time, flow stability, and response time to occlusion, depending on the presence of accessories such as valves, needles, and tubing, and depending on physical parameters such as temperature and liquid viscosity.

 

The results obtained showed that infusion drug delivery devices are sensitive to conditions of use, particularly at low flow rates and for larger volume syringes. In addition, the start-up time under certain conditions (very low flow rates) can be as long as several tens of minutes.

 

Throughout this project, the results and knowledge acquired were disseminated to the scientific and medical communities via various media. Initially, a website (www.drugmetrology.com) was created, providing direct and public access to communications related to the project. A workshop organized by the “MeDD” consortium and bringing together members of the scientific and medical communities was held in Utrecht (Netherlands) in May 2015, providing an opportunity to present the results of this project and discuss the implementation of traceable metrological approaches for infusion devices. A guide to good infusion practices was also drafted and made available on the project website.

PUBLICATIONS AND COMMUNICATIONS

BATISTA E., FILIPE E., BISSIG H., PETTER H.T., LUCAS P., OGHEARD F. and NIEMANN A.K., “European research project on microflow measurements – MEDD”, 9th International Symposium on Fluid Flow Measurement, Arlington, United States of America, April 14th-17th 2015.

BISSIG H., PETTER H.T., LUCAS P., BATISTA E., FILIPE E., ALMEIDA N., RIBEIRO L.F., GALA J., MARTINS R., SAVANIER B., OGHEARD F., NIEMANN A.K., LÖTTERS J. and SPARREBOOM W., “Primary standards for measuring flow rates from 100 nl/min to 1 ml/min – gravimetric principle”, Biomedical Engineering / Biomedizinische Technik, 60, 4, 2015, 301–316, DOI: 10.1515/bmt-2014-0145.

DAVID CH., MELVAD C., BISSIG H. and BATISTA E., “Research interlaboratories comparison for small liquid flow rates (2g/h to 600g/h)”, 16th Flow Measurement Conference (FLOMEKO), Paris, France, September 24th-26th 2013.

OGHEARD F., BATISTA E., BISSIG H., PETTER H.T., LUCAS P. and NIEMANN A.K., “Metrological assessment of micro flow-meters and drug delivery devices in the scope of the "MeDD" EMRP project”, 17e Congrès international de métrologie, Paris, France, September 21st-24th 2015, DOI: 10.1051/metrology/20150009004.

LUCAS P., SNIJDER R.A., TIMMERMAN A.M.D.E., BATISTA, E., BISSIG H. and OGHEARD F., “Best Practice Guide”, Version: 13-05-2015.

PARTNERS

  • VSL,
  • CETIAT,
  • CMI,
  • DTI,
  • IPQ,
  • METAS,
  • TUBITAK,
  • FH Lubeck,
  • UMC Utrecht