Intentional Yaw Misalignment and the Effects on Wind Turbine Noise


  • Ian Bonsma HGC Engineering
  • Nathan Gara HGC Engineering
  • Brian Howe HGC Engineering


A case study will be presented where a number of wind turbines in a project were intentionally yaw misaligned to investigate various effects. This paper investigates changes in sound level and special characteristics of wind turbine noise (amplitude modulation) due to the intentional yaw misalignment.

Author Biographies

Ian Bonsma, HGC Engineering

Ian Bonsma, PEng, INCE, has been involved with wind turbine noise issues for many years, beginning with HGC Engineering’s assessment of the Pubnico Point Wind Project in 2004. He has completed acoustic modeling and measurements for many wind energy projects and has extensive on-the-ground experience completing measurement campaigns as part of acoustic audits of entire wind energy facilities in Canada, the US and Honduras. He is actively involved with research associated with various aspects of wind turbine noise, and has prepared presentations for the MOECC, the Canadian Acoustical Association, the Canadian Wind Energy Association, the American Wind Energy Association, and is an active participant at International Wind Turbine Noise conferences. Ian is the technical lead for HGC Engineering’s ISO 17025 Accreditation for IEC 61400-11 (sound power level testing of wind turbines).

Nathan Gara, HGC Engineering

Nathan Gara is responsible for the procurement, deployment, and maintenance of any instrumentation related to the measurement of wind turbine noise and associated meteorology. He has extensive experience building and troubleshooting equipment for a variety of projects, including several wind farms. Since the beginning of his tenure with HGC Engineering, he has designed and implemented a remote-accessible sound monitoring system for wind farms that has improved both equipment reliability and measurement efficiency. Nathan managed the instrumentation of a research project and co-authored a paper that was presented at the International Wind Turbine Noise Conference in Rotterdam in 2017.

Brian Howe, HGC Engineering

Brian Howe is the Chairman of the Canadian Standards Association (“CSA”) Technical Subcommittee on Acoustic Noise Measurements of Wind Turbines, providing Canadian input to the international standards committee for IEC 61400. He currently sits on the Council of Canadian Academies’ Wind Turbine Noise and Human Health Panel. He prepared a study on behalf of the Ontario Ministry of the Environment, “Low Frequency Noise and Infrasound Associated with Wind Turbine Generation Systems, A Literature Review”, dated December 10, 2010 and has peer reviewed wind project studies and testified at Environmental Review Tribunals on their behalf. He has also made many presentations on the topic of wind turbine noise over the years to municipalities, to Professional Engineers Ontario, at CanWEA, Canadian Acoustical Association, and Inter-noise conferences, to the Ontario Government’s Engineer’s Professional Development Day, to the Rotman School of Management, at the International Wind Turbine Noise Conference in Lyon in 2007, Aalborg in 2009, and Rome in 2011, and at the International Low Frequency Noise Conference in Stratford-upon-Avon. Brian served on the organizing committee for the International Wind Turbine Noise Conferences in Denver in 2013, Glasgow in 2015, and Rotterdam in 2017, and sits on the organizing committee for the 2019 International Wind Turbine Noise Conference in Lisbon.




How to Cite

Bonsma I, Gara N, Howe B. Intentional Yaw Misalignment and the Effects on Wind Turbine Noise. Canadian Acoustics [Internet]. 2019 Oct. 16 [cited 2023 Dec. 1];47(3):66-7. Available from:



Proceedings of the Acoustics Week in Canada