Research leader: Franck Sgard
Coordinator: Jacqueline Caboret

  • Research projects
  • IRSST Publications
  • Scientific publications and communications
  • Prévention au travail articles

Context
Many workers are exposed daily to noise and vibration in the context of their work. It is well known that prolonged exposure to high noise levels leads to hearing loss and significant deafness. Regarding prevention, action can be taken either on the source of the noise, or on the environment where the sound propagation occurs, or even on the worker through the use of personal protective equipment. Vibration can be transmitted by portable vibrating tools (ex., grinders, chipping hammers, drills) or when vehicles (e.g., logging equipment, lift trucks, trucks, buses) are driven on more or less uneven surfaces. The first case involves exposure to hand-arm vibration, whose main effects come under the heading of hand-arm vibration syndrome, which includes vascular effects (Raynaud’s syndrome) and neurological and musculoskeletal disorders affecting the upper limbs. The second case more specifically involves exposure to whole-body vibration, which is a risk factor in the etiology of low back pain and degenerative lesions of the spine.

Objective
Noise and vibration research focuses mainly on the technical aspects of exposure to industrial noise and to hand-arm and whole-body vibration. In the case of noise, it entails parallel actions on all links of the chain (source, propagation environment, and worker). This involves proposing metrological tools or simulations to help workplace professionals better diagnose problems and evaluate sound exposure, implement good noise reduction solutions, and finally, improve communication in a noisy environment in order to prevent accident risks. In the case of vibration, it entails a better characterization of the risks produced by portable tools, by the operation of industrial machines, as well as by the driving of different categories of vehicles. The object of the research is also a better evaluation, selection and design of anti-vibration solutions, while including some aspects related to biodynamics in order to better understand the behaviour of the human body when exposed to a vibrating environment. The research is conducted in the laboratory or in the field with both experimental and modeling components. Its aim is primarily to reduce exposed workers’ risks of health impacts (ex., deafness, hand-arm vibration syndrome, low back pain).

Research orientations

Vibrations:

• Characterization of vibration exposure and vibrating environments;
• Support tools for the selection and design of less vibrating machines and anti-vibration products (seats, gloves, anti-vibration handle);
• Dose-effect relationship and biodynamics of the human body.
 

Favoured orientations
Emphasis is on tools for diagnosing noise and vibration exposure in workplaces as well as on support tools for evaluating and designing the technical means to be implemented to limit exposure. In particular, more fundamental research efforts are being undertaken in order to better understand the interaction between the worker and the surrounding sound field (acoustical behaviour of hearing protection coupled to the ear, communication in a noisy environment) and the body's reactions when exposed to vibration, to elucidate exposure-response relationships, and to evaluate the effect of independent variables (ex., posture, gripping strength) on the vibration dose.

This field’s thematic programs address noise and vibration in a balanced way. They are based on reflection originating from colloquia on noise and hand-arm vibration organized in March 2007 and September 2008, respectively. In addition to the dissemination of knowledge, these colloquia in fact identified the community’s needs and led to the proposal of priority research orientations and themes consistent with these needs. The noise-related thematic programs cover the three levels of the noise chain (source, propagation environment, and the worker). The vibration-related thematic program addresses hand-arm vibration exposure. Another program pertaining to whole-body vibration, and suspension seats in particular, is currently being defined.

The field has three thematic programs:

• Portable tools (noise and vibration);
• Sound propagation in the workplace (noise);
• Hearing protection (noise)

Our means 
For the noise area, the team has standard measurement tools: dosimeters, sound level meters, and microphones; the latter can be connected to the B&K PULSE analysis system or to the 01dB system. The team also has a B&K intensity probe. One research project that has just begun will enable the IRSST to obtain an acoustical intensity mapping system with an integrated position sensor for identifying noise sources and for measuring their acoustical power. The researchers have access to a reduced scale anechoic chamber used for calibrating noise dosimeters and microphones. These calibrations are performed for all occupational hygienist in the Québec OHS network. The laboratory that manages this chamber has CLAS accreditation (Calibration Laboratory Assessment Service) from the Standards Council of Canada, thus attesting to high standard of precision and quality in its equipment and methodologies. Finally, a partnership with the École de Technologie Supérieure (ÉTS) is currently being developed in order to implement a common IRSST/ÉTS experimental infrastructure for conducting IRSST and ÉTS acoustical research studies, particularly on noise and the mechanical vibrations generating it or resulting from it (structural acoustics). This infrastructure, consisting of a semi-anechoic chamber (100 m3) paired with a reverberant chamber (216 m3), will be located on ÉTS’s premises. The researchers have developed several research software programs:

• code for vibroacoustic calculation based on SEA
• code for predicting acoustical performances of machine enclosures
• code for predicting the acoustical field in rooms based on the image source methode
• code for calculating diffuse field transmission loss of rectangular and circular apertures

They also have access to numerical tools based on the finite element and boundary element methods.

For whole-body vibration exposure, the laboratory is equipped with a vibration simulator that reproduces the vertical vibration of various categories of vehicles. The simulator is used to evaluate the efficiency of suspension seats, and to study the behaviour of the human body when exposed to vibration. The simulator consists of a platform mounted on two hydraulic actuators providing a total range of ±100 mm. The system's useful low frequency response is up to 25 Hz. The team also benefits from two multichannel vibration and acoustic signal acquisition and analysis systems (PULSE and 01dB).

For research on hand-arm vibration exposure, an electrodynamic shaker capable of reproducing the vibrations of different categories of tools is used. Test benches are available for evaluating the effectiveness of anti-vibration gloves and handle-covering materials, and for evaluating the vibration emission values of different categories of tools (e.g., chipping hammers, riveting hammers, etc.). A laser vibrometer system is also available for performing measurements without contact. Furthermore, the team has a pressure distribution measuring system that includes a matrix of 176 sensors and an instrumented handle with sensors for measuring the pushing and gripping forces in studies evaluating the biodynamic behaviour of the hand-arm system.

In addition to standard software for analyzing and processing vibration signals, internal software has been specially developed to automate signal processing according to the methods defined in the current international standards for hand-arm and whole-body vibration exposure assessments.

Our Partners
The IRSST has ties with academic, institutional, as well as industrial partners.

Regarding academic partners, the Acoustical Group at Université de Sherbrooke (GAUS) has for a long time been contributing to the IRSST’s research, and has even held an Industrial Chair in this area. This group continues to have a strong association with the IRSST by collaborating on research activities and projects of common interest. Concordia University’s Department of Mechanical and Industrial Engineering is also an important partner in the IRSST’s research activities in the field of vibration. The École de Technologie Supérieure is another important collaborator, particularly in research on hearing protection. This partnership is currently being reinforced by the establishment of shared IRSST/ÉTS experimental research infrastructures. The University of Ottawa is collaborating with the IRSST on communication problems in noisy environments. Laurentian University, the University of Western Ontario, and Guelph University are also collaborators in the field of whole-body vibration. Researchers in this field are all associate professors in at least one of the universities, such as the Université de Sherbrooke, the École de Technologie Supérieure, and Concordia University. These partnerships allow expertise to be shared in the training of highly qualified personnel via the co-mentoring of doctoral or master’s students.

Furthermore, several companies (Sonomax, SoftdB, Canmet, Soredem, Optisplit, Chicago Pneumatic, Audeval, Part Headquarters) have contributed to the development of sound diagnostic tools and technical solutions for reducing workers’ exposure to noise and vibration. These solutions are being or have been the subject of collaborative activities with the IRSST or have been evaluated by the researchers in this field in the context of expertise.

Finally, scientific collaboration has been established with institutional partners such as the INRS in France in the field of noise. Several OHS associations have collaborated over the years in making studies possible, by providing access to sites necessary for data collection, and by allowing the results of the research to be applied to the workplaces.

Impacts 
In addition to the direct impacts in workplaces for the purpose of identifying risks and reducing exposure, research in the noise and vibration area is aimed at generating new knowledge and increasing the pool of researchers in this area. Consequently, the results of the studies are being widely published in research reports, theses and scientific journals, as well as being disseminated at large-scale scientific events. Based on the needs expressed by the users, guides and technical fact sheets are developed and made available to companies and professionals in occupational health and safety. In the context of scientific activities in this area, events are periodically organized in order to make the actors in this area of interest aware of the research work being done, to determine the community’s needs, and to identify new avenues of research and partnerships. Active participation on the international standardization committee on vibration (ISO TC 108/SC4) and on hearing protection (ISO TC 159 WG5) are also allowing the research results to be integrated into the development of new standards. The researchers are also involved in the organizing committees of international conferences (Vibrations 2009, INTER-NOISE 2009, Congrès Français d’Acoustique 2010). By welcoming trainees and students participating in certain research activities, knowledge can be transferred and highly specialized resources can be developed. In addition to research projects and activities being carried out, technical expertises are occasionally performed,allowing a direct link with the workplaces, while providing them with solutions to certain problems where a lack of specialized resources may exist.