GaAs layers were grown by MBE. The layers were then damaged by 3 MeV proton irradiation and later annealed. We performed Hall effect and low-frequency noise measurements at temperatures between 77 K and 300 K after each step. Several generation - recombination noise components created by proton irradiation disappeared completely after the annealing. The 1/f noise created by proton irradiation did not depend on the measurement temperature. It could be reduced systematically by annealing at temperatures in the range of 543 - 563 K. In an isochronal annealing procedure, annealing at different temperature for a constant length of time, we found annealing effects on the free charge carrier concentration but not on the 1/f noise. 1/f noise is a fluctuation in mobility originating from clusters of defects. The annealing of damaged GaAs characterizes these noise generating defects by an activation energy of 1 eV.