Present wind turbine gearbox design usually includes one or two planetary gear stages and at least one high
speed helical gear stage, which play an important role regarding noise and vibration behaviour. Next to the
overall noise of the gearbox and the structure–born noise on the gearbox housing also tonal noise is
becoming a much more important issue in recent years. Since tonal noise is problematic due to the human
perception as “uncomfortable”, avoidance is important. Conventional theories regarding low noise gear
design are not developed in view of tonal noise. This leads to the question: How to deal with tonal noise in the
design stage and which gear parameters can be used for an optimisation regarding good tonal noise
behaviour?