Thirty-three of 36 neighbours of the proposed wind farm, east of Palmerston North, oppose an extension because of noise concerns.

New Zealand Windfarms yesterday defended its record on turbine noise as it sought the right to add 56 turbines on the eastern side of the Tararua Ranges. The company, which already has consent for 97 turbines on the Palmerston North side of the ranges, also confirmed 32 of them could instead be used for the extension, if approved.

Horizons Regional Council and Tararua District Council started a joint hearing in Palmerston North yesterday on the proposal.

New Zealand Windfarms has built 65 turbine towers at Te Rere Hau, but is awaiting the outcome of the hearing before deciding its next move.

Despite a series of complaints about noise, the company argued it could show it was complying with consent conditions. Landscape and visual effects were the second most common objection.

Project manager Alison van Polanen said the company had "demonstrated a commitment to better understanding acoustic emissions" by getting experts to conduct tests.

Part of the Te Rere Hau hearing will coincide with a hearing for the proposed 121-turbine Turitea Wind Farm, also near Palmerston North.

Commissioner David McMahon said next week's clash was unfortunate, but decided the Te Rere Hau hearing should not be delayed.

New Zealand Windfarms lawyer Mike Holm described the plan as a "relatively modest extension of an existing wind farm".

Mr Holm said the three commissioners should not take the impact of the planned Turitea project into consideration.

However, cumulative noise effects were unlikely to present a problem for the company if both projects went ahead, he said.

New Zealand Windfarms chief executive Steve Cross confirmed there was doubt the 32 turbines initially intended for the western side of the ranges would go there.

Those turbines had already been ordered from Christchurch turbine supplier Windflow Technology, but the wind resource at the eastern extension would be better, he said.