In a method for adapting a hearing aid, and a hearing aid arrangement for improving the directivity of a hearing aid with a number of microphones that are connected to one another for generating a directional characteristic, the hearing aid is exposed to acoustic waves in a room for precision measuring while the user is wearing it, and the directional characteristic is registered. The filter parameters that arise therefrom are supplied to parameterizable filters in the hearing aid that are connected downstream from the microphones, and the desired ideal directional characteristic can be approximated taking the individual conditions into account when the hearing aid is worn.