Excessive noise exposure is probably the most prevalent of occupational exposures. Work-related hearing loss is the greatest source of occupational-disease claims. Noise exposure can be controlled by the use of hearing protection, and by administrative and engineering measures. Engineering control traditionally involves 'passive' methods, which are not cost-effective at low frequency. Recently, a new technique of noise control - Active Noise Control (ANC) - has been developed. This involves using noise to cancel existing noise, and is particularly effective at low frequencies. The objective of the proposed research project is to determine the feasibility of applying ANC to the control of workplace noise exposure. Industries with workers exposed to significant low-frequency noise have been identified and have agreed to support the project. These industries work in fuel production (Westcoast Energy, BC Gas), electrical-power generation (BC Hydro) and sea transportation (ship engine rooms - BC Ferries). For active noise control to be effective, the noise to which workers are exposed must have particular characteristics. Measurements will be made of the relevant characteristics of the noise in the target workplaces. These will be analyzed to determine to what extent they have the required characteristics. Using computer models, workrooms in the target sites will be modeled theoretically and possible ANC implementations evaluated. Lab-based experiments will be performed to confirm and fine-tune the optimum configurations. One or more workplaces will be chosen as demonstration projects. In each, an optimized ANC system will be implemented and the resulting noise reduction and cost-effectiveness will be evaluated. The results of the research will be generalized to produce guidelines allowing the feasibility of reducing noise exposure using ANC, and the expected associated noise reductions and costs, to be evaluated in other workplaces.
