Acoustic stimulation treatments against tinnitus could be most effective when tinnitus pitch is within the stimulated frequency range.Hear Res. 2010 Oct 01; 269(1-2):95-101.HR
Acoustic stimulation with hearing aids or noise devices is frequently used in tinnitus therapy. However, such behind-the-ear devices are limited in their high-frequency output with an upper cut-off frequency of approximately 5-6 kHz. Theoretical modeling suggests that acoustic stimulation treatments with these devices might be most effective when the tinnitus pitch is within the stimulated frequency range. To test this hypothesis, we conducted a pilot study with 15 subjects with chronic tinnitus. Eleven subjects received hearing aids and four subjects noise devices. Perceived tinnitus loudness was measured using a visual analog scale, and tinnitus-related distress was assessed using the Tinnitus Questionnaire. After six months of device usage, reductions of perceived tinnitus loudness were seen only in subjects with a tinnitus pitch of less than 6 kHz. When subjects were grouped by tinnitus pitch, the group of patients with a tinnitus pitch of less than 6 kHz (n = 10 subjects) showed a significant reduction in perceived tinnitus loudness (from 73.4 +/- 6.1 before to 56.4 +/- 7.4 after treatment, p = 0.012), whereas in subjects with a tinnitus pitch of 6 kHz or more (n = 5 subjects) tinnitus loudness was slightly increased after six months of treatment (65.0 +/- 4.7 before and 70.6 +/- 5.9 after treatment), but the increase was not significant (p = 0.063). Likewise, tinnitus-related distress was significantly decreased in the low-pitch group (from 31.6 +/- 4.3 to 20.9 +/- 4.8, p = 0.0059), but not in the group with high-pitched tinnitus (30.2 +/- 3.3 before and 30.0 +/- 5.1 after treatment, p = 1). Overall, reductions in tinnitus-related distress in our study were less pronounced than those reported for more comprehensive treatments. However, the differences we observed between the low- and the high-pitch group show that tinnitus pitch might influence the outcome of acoustic stimulation treatments when devices with a limited frequency range are used.