CHIRP AUDITORY STEADY -STATE RESPONSE AS A HEARING SCREENING TOOL IN HIGH- RISK INFANTS

Background:Newborn hearing screening with automated procedures usually uses broad band stimuli, such as click. Studies using the Auditory Steady-State Response (ASSR) that used specific frequency chirps named narrow band CE-chirps have shown obvious diagnostic results. Objective:To assess the value of the binaural multi-frequency chirp ASSR as a hearing screening tool. To compare chirp ASSR and click ABR as a tool for early diagnosis of hearing loss in infants with risk factors for hearing loss.Methodology: Two groups of infants were studied, group I (28 infants with risk factors) with one or more risk factor for permanent hearing loss, group II (ten infants without risk factors). Their age ranges from one to six months. Assessment of middle ear pressure using immittancemetry, and hearing threshold estimation using Click ABR and Chirp ASSR were done. Results: When comparing hearing threshold of [group (I) infants with risk factors], and [group (II) infants without risk factors] it was found that there was no statistically significant difference when hearing was evaluated by using click ABR or Chirp ASSR.By comparing average ASSR (Average thresholds of1000, 2000 and 4000 HZ) threshold with ABR threshold, there was no statistically significant difference. There was high positive correlation between ABR threshold and average ASSR. Conclusion: Chirp ASSR can be used for assessment of hearing thresholds in infants with the same accuracy of Click ABR thresholds, with more advantage perceived by ASSR in the form of frequency specific threshold estimation. The binaural multi-frequency chirp ASSR can be used as a hearing screening tool.