Reduction of Gearbox Tonalities with Active or Passive Damping Devices

Vibrations in the gearbox of a wind turbine can cause tonalities (noise with a fixed frequency, e.g. whistling noise). These tonalities are particularly unpleasant for people and thus they have to be specifically considered in the evaluation of noise emissions. In accordance with legal standards, surcharges are therefore assigned to the determined sound power level of the wind turbine. With this surcharge, the authorized limits for noise emissions or the contractually agreed noise levels may be exceeded.

Therefore, tonalities have to be reduced. In the wind energy sector, Wölfel has many years of experience in the application of active and passive absorbers, which compensate the vibrations at their source before they can spread. This is achieved by precisely applied counter-vibrations.

By moving the black dots you can calculate your individual payback period with our interactive tool:



Amortisation after


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Noise-reduced operation of your WTG can massively reduce the yield of your wind farm. With ADD.Sound you minimize tonality and can return to the normal operation mode. This calculation includes all costs including installation.

With more than 1.000 systems in the market, we are proud to be the technology leader in the field of active damping devices for the reduction of gearbox tonalities.

  • ADD.Sound compensates several orders of tonal gearbox vibrations at variable speed (over the entire speed range of the wind turbine)
  • One active absorber ADD.Sound each is mounted on the torque supports (can also be retrofitted; small installation space required)
  • A compact control cabinet is installed in the nacelle
  • Due to the speed-adaptive control algorithm, ADD.Sound generates active forces which eliminate the tonal excitation forces in the gearbox
  • Tonal sound is cancelled over the entire range of speed (broadband effect, simultaneous compensation of several tonalities)

Solution for mastering tonalities with fixed frequency: Passive damper – TMD.Sound

  • Compensation of one order of tonal gearbox vibrations at one fixed speed (mostly the rated speed of the wind turbine)
  • One passive absorber TMD.Sound each is mounted on the torque supports (can also be retrofitted)
  • TMD.Sound is exactly adjusted to the tonality frequency at rated speed
  • TMD.Sound applies a force that is exactly opposite to the excitation
  • Tonal sound at rated speed is cancelled – no energy supply is required

Please contact us personally


We would be pleased to support you in solving your problem concerning "Wind turbine vibrations" and advise you on questions regarding our system and service offerings in the areas of structural health monitoring, vibration reduction, sound and noise as well as structural design.

Timo Klaas

+49 40 524715-265

Dipl.-Ing. Bernd Wölfel

Lorena Sproll-Astorquiza

+49 931 49708-761