Page 2
This deafferentation (or cochlear synaptopathy, as it has been called has been described as “hidden hearing loss”, since it is not possible to detect it with the standard measurements of hearing, namely audiometry. In addition to this alteration, there is bound to be observed a probable malfunction in the medial olivocochlear system (MOCS), which plays a fundamental role in the recognition of target tones in the presence of noise.Thus, the hypothesis is that individuals with normal audiometric thresholds and a complaint of tinnitus present with more difficulties in speech recognition in acoustically unfavorable environments as compared to those who do not present with the symptom. Accordingly, the purpose of the present study was to investigate the performance in the LSP test (list of sentences in Portuguese) of individuals with normal audiometric thresholds, with and without tinnitus.
Twenty individuals of both genders, who met the following inclusion criteria, were evaluated: aged between 18 and 45 years (the age limit was established so that the aging process did not interfere in the results); normal hearing (from 0 to 20 dB dB HL), at frequencies from 250 to 8000 Hz by air conduction; presence or absence of tinnitus symptoms; presence of distortion product otoacoustic emissions (DPOAE) (3 dB S/N above background noise, in all f2 surveyed). Individuals presenting with hearing loss, a complaint of neurological dysfunctions and problems in the middle and/or external ear were excluded from the study.
The patients were divided into a tinnitus group (TG), comprising seven individuals with tinnitus symptoms, bilaterally, and a control group (CG), comprising 13 individuals without a complaint of tinnitus. All participants in the tinnitus group presented with a complaint for at least the previous six months, always bilaterally. Importantly, all the patients in the tinnitus group were referred from medical care settings, through which an in-depth investigation of their complaint had been made and any possible confounding factors in this study had been ruled out.