Services on Demand
Revista Brasileira de Otorrinolaringologia
Print version ISSN 0034-7299
FERRAZ, Orley Baena; FREITAS, Sérgio Vaz de and MARCHIORI, Luciana Lozza de Moraes. Analisys of normal hearing subjects steady-state auditory responses. Rev. Bras. Otorrinolaringol. [online]. 2002, vol.68, n.4, pp.480-486. ISSN 0034-7299. http://dx.doi.org/10.1590/S0034-72992002000400005.
Introduction: Auditory steady-state are electrophysiologic responses elicited by continuous tones, modulated in amplitude that can be recorded by surfaces electrodes, and allows a more detailed, and objective auditory evaluation due to frequency-specific and objective responses analysis. Objective: To evaluate if auditory steady-state (recently infiltrated in Brazil) is really an efficient and trustworthy new technique that might be useful as a routine test in objective audiometry. Study design: clinical prospective. Material and Method: This present paper has analyzed normal-hearing auditory steady-state responses at frequencies of 500, 1000, 2000 e 4000Hz, recorded from a group of 25 subjects between 21 and 40 years of age. The subjects had hearing thresholds of 0 to 15dB HL, and none of them had any personal history of hearing impairment. Results: Steady-state evoked responses in the frequency-domain were easily detected bilaterally, using statistical techniques, in all of the subjects with intensities varying between 20 and 40dB HL, in at least six of eight studied frequencies, corresponding to 97% of 200 waited responses. A high concentration of the responses (85%) were obtained at intensities down to 30dB HL, of which 80% to tones of 500Hz; 84% to tones of 1KHz; 90% to tones of 2KHz, and 86% to tones of 4KHz. Conclusion: Auditory steady-state evoked responses reported here were quite similar to several studies done in other countries, that is, nearly 15 to 20dB HL from behavioral thresholds. The main advantages over other electrophysiologic auditory evaluation techniques were confirmed as: the recording analysis objectiveness, and steady-state frequency-specific responses, so it is believed to be a technique that will soon play an important role in the clinical objective audiometry.
Keywords : auditory responses; steady-state; objective audiometry.