A method for fitting a hearing aid device with active occlusion control to a user, said hearing aid device comprising • An outside microphone for sensing sound of an environment of said user; • A receiver configured for emitting sound into an ear canal of said user; • Means for active occlusion control (8, 9); Said means for active occlusion control (8, 9) comprising: • A canal microphone configured for sensing a sound pressure in said ear canal of said user; • An occlusion control compensator filter arranged in a feedback loop and configurable by a compensator filter dataset; Said method comprising the steps of: A) Inserting said hearing aid device at least partially into said ear canal and establishing a communication connection (26, 27, 28) between said hearing aid device and a fitting device and switching said hearing aid device into a fitting mode; B) Obtaining a complex frequency-dependent plant transfer function defined as a transfer function from an input of said receiver to an output of said canal microphone by obtaining a plant stimulus and presenting it by said receiver, sensing a resulting sound in said ear canal by said canal microphone and analyzing said resulting sound in regard to said plant stimulus by plant measurement analysis means; C) Obtaining an objective frequency-dependent occlusion effect function (OE, |OE|) and/or at least one property of it by measuring said objective frequency-dependent occlusion effect function (OE, |OE|) and/or said at least one property of it while said user's voice is active and/or while said user's body is vibrated by a vibration means, by sensing a canal sound in said ear canal by said canal microphone, by obtaining a reference sound by said outside microphone or other reference microphone or from said vibration means, respectively, and by analyzing said canal sound in regard to said reference sound by occlusion measurement analysis means (13, 14, 16); D) Carrying out a determination of said compensator filter dataset by using said complex frequency-dependent plant transfer function and by using said objective frequency-dependent occlusion effect function (OE, |OE|) and/or said at least one property of it; E) Configuring said occlusion control compensator filter with said compensator filter dataset. • An outside microphone for sensing sound of an environment of said user; • A receiver configured for emitting sound into an ear canal of said user; • Means for active occlusion control (8, 9); • A canal microphone configured for sensing a sound pressure in said ear canal of said user; • An occlusion control compensator filter arranged in a feedback loop and configurable by a compensator filter dataset; A) Inserting said hearing aid device at least partially into said ear canal and establishing a communication connection (26, 27, 28) between said hearing aid device and a fitting device and switching said hearing aid device into a fitting mode; B) Obtaining a complex frequency-dependent plant transfer function defined as a transfer function from an input of said receiver to an output of said canal microphone by obtaining a plant stimulus and presenting it by said receiver, sensing a resulting sound in said ear canal by said canal microphone and analyzing said resulting sound in regard to said plant stimulus by plant measurement analysis means; C) Obtaining an objective frequency-dependent occlusion effect function (OE, |OE|) and/or at least one property of it by measuring said objective frequency-dependent occlusion effect function (OE, |OE|) and/or said at least one property of it while said user's voice is active and/or while said user's body is vibrated by a vibration means, by sensing a canal sound in said ear canal by said canal microphone, by obtaining a reference sound by said outside microphone or other reference microphone or from said vibration means, respectively, and by analyzing said canal sound in regard to said reference sound by occlusion measurement analysis means (13, 14, 16); D) Carrying out a determination of said compensator filter dataset by using said complex frequency-dependent plant transfer function and by using said objective frequency-dependent occlusion effect function (OE, |OE|) and/or said at least one property of it; E) Configuring said occlusion control compensator filter with said compensator filter dataset.