Project background:
Individual hearing protection remains the most common short-term solution to protect workers exposed to high noise levels because of its ease and speed of implementation and its relatively low cost. Nevertheless, wearing hearing protectors is still associated with several problems: (i) their use may be a cofactor for the risk of accidents, (ii) their actual performances are often very different from the one obtained in the laboratory, which may lead to an under protection of workers, (iii) the standardized attenuation measurement techniques to assess protectors individual performances, like REAT (real ear attenuation at threshold) or IL (insertion loss), are difficult to implement in the workplace, (iv) the new F-MIRE (field microphone-in-real-ear) measurement technique, while more appropriate for on-site use, does not yet provide an individual performance estimate, and (v) the recommended wearing time of hearing protection devices to reduce the exposure to harmful noise is often not enforced because of problems of discomfort and, unfortunately, comfort is often forgotten in the protector design process which is generally based on an empirical approach or very simplified models.
The project main objective is to address the issues outlined above by developing modeling tools and measurement methods to better evaluate and to improve the performances of hearing protectors while integrating some parameters that may affect comfort.
This is a collaborative research project between IRSST (Robert-Sauvé research institute in occupational health and safety) and ÉTS (a school of engineering in the University of Quebec). The research team includes two researchers from IRSST (Franck Sgard and Hugues Nélisse, in acoustics) and two professors from ÉTS (Frédéric Laville, in acoustics and Yvan Petit, in biomechanics) that will direct the thesis work of the three students. The team includes also a full time and a part time post-doctoral research associates and scientific support personnel from the two institutions. Funding is contingent on the official project approval by the IRSST management.

Subject description : Study of the biomechanical parameters and of the occlusion effect of the system "earplug / ear canal" : numerical modeling and experimental validation

* Develop a measurement set-up to assess ear canal biomechanical parameters.
* Develop a measurement set-up to assess occlusion effect.
* Based on the model developed in parallel under thesis topic #2, develop a numerical model of structure-borne transmission through the head - both internal and external paths should be considered - allowing for the assessment of the occlusion effect together with the bone conduction path in double protection hearing protectors (earplug + earmuff).
* Validate the bone conduction model for the occlusion effect (using experimental measurements based on a microphone doublet and audiometric tests on human subjects) and for the double protection (using literature results).
* Use the results obtained with this model in order to supplement the results obtained under thesis topics #1 and #2 and provide guidelines for the design of an earplug with minimum occlusion effect or a double protection set with maximum attenuation.

Background prerequisites : one of the two domains, acoustics or biomechanics, with an interest for the other domain.

Start date: 31 August 2009; duration : 4 years.

Details of the PhD students' financial support are to be discussed with the contact persons

For information or to submit your application (CV + two references + university transcripts) : please contact

Frédéric Laville, Professor
Département de génie mécanique
Ecole de technologie supérieure
Montréal, QC, H3C 1K3 CANADA
Tél : +1(514)396-8662
Fax: +1(514)396-8530


Yvan Petit, Associate Professor
Département de génie mécanique
Ecole de technologie supérieure
Montréal, QC, H3C 1K3 CANADA
Tél : +1(514)396-8691
Fax: +1(514)396-8530