Document Type : Review Articles

Authors

• Aliakbar Nasr Esfahani ¹
• Elham Rajabpour ¹
• Mohamad Hussein Nilforoush ²
• Mahsa Sepehrnejad ³
• Parisa Rasoulifard ¹

¹ Audiology Department, School of Rehabilitation Sciences, Tehran University of Medical Sciences, Tehran, Iran

² Audiology Department, School of Rehabilitation Sciences, Isfahan University of Medical Sciences, Isfahan, Iran

³ Isfahan Cochlear Implant Center, Isfahan University of Medical Sciences, Isfahan, Iran

Abstract

Introduction: Cochlear dead zones are defined as areas where the inner hair cells have been destroyed. Thresholds on the audiograms show the integrity of those parts of the ear that are tested. Care must be taken in interpretating audiograms. Thanks to the advances in understanding of cochlear functions, it is now possible to spot false responses that come from dead zones of the cochlea. Recently, cochlear dead regions have been detected via TEN (Threshold Equalizing Noise) test in which ipsilateral broadband noise and threshold shifting are used.Materials and Methods: A review of the literature on the subject of dead zones published from 1993 to 2003 was performed using PUBMED, EBSCO, SCIENCE DIRECT, GOOGLE SCHOLAR THIEME PROQUEST databases and library sources. Keywords were “cochlear dead zone”, “traveling wave”, “ten (threshold equalizing noise) test”, “ipsilateral noise” and “real-ear measurement for hearing aids prescription”.Conclusion: The identification of cochlear dead zones involves understanding the traveling wave of the cochlea. In this study, we will discuss dead zones and their warning signs and will represent a test strategy in identifying cochlear dead zones that was formerly developed by Moore. Knowing this procedure can help audiologists improve their hearing tests and their hearing aid fittings.Keywords: Cochlear Dead zone, Traveling wave, TEN (Threshold equalizing noise) test