[Evaluation test and masking therapy of subjective tinnitus].

Objective: To undergo tinnitus evaluation test and masking therapy of subject tinnitus associated with sensorineural hearing loss as a reference for diagnosis and guiding masking therapy.

Methods: The 66 patients with subject tinnitus were diagnosed as sensorineural hearing loss. Sixty-six patients divide into three groups according to the results of pure tone audiometry, including steep drop type in 28 patients, slow drop type in 20 patients, and flat type in 18 patients. All the patients underwent tinnitus evaluation tests (pitch matching, intensity matching, tinnitus masking curves, residual inhibition) and masking therapy.

Results: Tinnitus with steep drop type manifest was as low intensity [average intensity (5.7 +/- 2.9) dB (x(-) +/- s)] and high frequency (median with 4750 Hz). Residual inhibition was almost positive, but was usually consistent with convergence and congruence tinnitus masking curves. Masking therapy had better effect in the treatment of this type of tinnitus (effective rate 89.3%). Tinnitus with slow drop type manifest was as low intensity [average intensity: (6.2 +/- 4.8) dB] and high frequency (median: 4050 Hz). The distribution of residual inhibition and tinnitus masking curves had no obviously characteristics. The effective rate of masking therapy of this type of tinnitus (55.0%) was higher than tinnitus with flat type but low than that of tinnitus with steep drop type. The intensity of tinnitus with flat type [average intensity: (9.2 +/- 5.0) dB] was higher than that of the previous groups. The distribution of frequency of this type had no obviously characteristics. The residual inhibition was almost negative, and was usually consistent with divergence and persistence tinnitus masking curves. Masking therapy had unsatisfactory curative effect in the treatment of this type of tinnitus (effective rate 11.1%). The effective rate of masking therapy was significant differences among the three groups (chi(2) = 9.127, P < 0.05).

Conclusions: For the tinnitus patients with steep drop type audiometric curve, they are recommended masking therapy. For the tinnitus patients with slow drop type audiometric curve, masking therapy may be attempted to perform. For the tinnitus patients with flat type audiometric curve, they do not recommend the masking therapy.