According to the World's Health Organization (WHO), occupational noise represents one of the most important source of Noise-Induced Hearing Losses and deafness, leading more generally to severe losses of productivity. Thus, the social costs associated with occupational noise is among the most important, worldwide. Some activities are associated with particularly high noise levels, such as the construction industry.
More specifically, the caterpillar industry is facing critical noise issues, likely to be dominant in the low-frequency range, especially affecting the operators inside the cabin of manned construction vehicles. Since some of the internal noise problems are likely to be dominated by cabin and structural resonances, an active modal control solution is expected to provide some interesting noise reduction benefit.
The concept of electroacoustic absorber, developped in the Acoustic Group at LTS2 is one interestng candidate for such problem. It consists of loudspeakers, used as membrane absorbers, the acoustic impedance of which can be modified to target optimal absorption for cavity modes in the low-frequency regime, in a broadband manner (almost one frequency decade between 20 Hz and 200 Hz).
After a quick review of the existing noise problem occurring in excavators, the work will consist in:
developing a FEM model on COMSOL Multiphyiscs to identify the possible sources of noise inside the cabin (cavity resonance, structural resonance of the windows, etc.)
developing a model of the excavator cabin to measure noise immission inside the cabin
developing electroacoustic absorber prototypes to fit the constraints of the application (size, weight, etc.) and assess their noise reduction performance.
Profile: Mechanical engineering, Electrical engineering, Micro-engineering, Physics
Prerequisites: Audio Engineering (MA1)
Context: Theory (20%), design (60%), experiments (20%)