A fitting method is provided for a multichannel hearing aid with at least one low frequency channel having an individually adjustable compressor. The method comprises the steps of first adjusting the characteristic of the compressor according to the hearing loss to be compensated by the hearing aid, followed by the step of increasing the compression ratio of the characteristic of the compressor in the at least one low frequency band. The at least one low frequency channel may further comprise an offset amplifier adding an offset gain to the compressor characteristic, and the method may further comprise the step of adjusting the offset gain in the range from -20 dB to 20 dB. After adjustment according to the method, compressors operating at low frequencies enhance low level signals and attenuate high level signals whereby perception of occlusion is suppressed.