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The normal hearing sensitivity, as evidenced by audiometric thresholds within the normal range up to 8000 Hz, may thus be masking subclinical auditory changes. The hypothesis is that, in the present study, these neural changes would be reflected by the thresholds for the LSP test with speech noise, which were statistically higher in the tinnitus group. In a way, it can be said that the results of this study converge towards other studies in regard to psychoacoustic behavior.
An important limitation to this study is that the high frequency thresholds (> 8000 Hz) were not obtained. Along with the processes described above, it is possible that a significant loss at ultra-high frequencies is also present in the cases of tinnitus, which contributes to worsening the performance. In a recent study investigating deafferentations in young people exposed to noise, a statistical difference was observed in ultra-high frequency audiometric thresholds. The authors concluded that differences between groups (exposed and unexposed) were due to deafferentations. However, the striking differences in the ultra-high frequency thresholds may justify the divergent performance among the evaluations performed.
Regardless of the hypotheses raised, the results presented in this study highlight the importance of investigating subclinical auditory aspects, taking into consideration the complaints brought by the patient. Even with audiometric thresholds within normal ranges, the symptom should be investigated by using instruments that can reproduce and/or reveal facts evidencing any difficulty or dysfunction of the system. This would be the first step towards an appropriate intervention.
CONCLUSION
The performance of individuals with normal hearing and a complaint of tinnitus in speech recognition in the presence of competitive noise was worse than in individuals without the symptom, especially in the step with speech-noise noise.
The analysis sums up that, in fact, the control and tinnitus groups are different in regard to the performance in speech tests in the presence of noise.
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