We auditorily stimulated patients affected by subjective tinnitus with broadband noise containing a notch around their tinnitus frequency. We assessed the long-term effects on tinnitus perception in patients listening to notched noise stimuli (referred to as windowed sound therapy [WST]) by measuring the variation of subjects' tinnitus loudness over a period of 2-12 months. We tested the effectiveness of WST using non-notched broadband noise and noise of water as control sound therapies. We found a significant long-term reduction of tinnitus loudness in subjects treated with notched noise but not in those treated with control stimulations. These results point to the importance of the personalized sound treatment of tinnitus sufferers for the development of an effective tinnitus sound therapy.