OTTAWA – Health Canada says it has tweaked its methods for a study on the possible link between wind farms and the adverse health effects reported by those living near them.

Ottawa announced last summer it would conduct the study, a decision that was lauded by opponents of the towering turbines.

The department says revisions to the plan were informed by more than 950 comments submitted by residents during a public consultation.

It says changes were made to the assessment of infrasound and a questionnaire to be administered by Statistics Canada.

Turbine opponents contend that exposure to low-frequency noise and vibrations from wind turbines _ in particular, inaudible infrasound _ can lead to sleep disorders, headaches, depression, anxiety and even blood pressure changes.

The $1.8-million study will initially focus on residents in 2,000 dwellings near eight to 12 wind-turbine installations.

There are about 140 such land-based wind farms in Canada, most of them in Ontario and Quebec.

The study is being conducted by a team of more than 25 experts in acoustics, health assessment and medicine, including four international advisers.

Results are expected in late 2014.