tailieunhanh - Science to practice in audiology (Third edition): Part 2

(BQ) Continued part 1, part 2 of the document Science to practice in audiology (Third edition) has contents: Masking for pure-tone and speech audiometry, outer and middle ear assessment, evoked physiologic responses, disorders of the auditory system, screening for hearing loss, hearing aids, implantable devices, vestibular system. Invite you to refer. | 9 Masking for Pure-Tone and Speech Audiometry After reading this chapter you should be able to 1. Understand why the non-test ear NTE needs to be masked in some cases in order to obtain true thresholds in the test ear TE . 2. Know what is meant by interaural attenuation IA and the minimum IA values used for each transducer when making decisions about the need to obtain masked thresholds. 3. Recognize from the unmasked thresholds when masked thresholds must be obtained apply the decision-making rules for masking when testing by air conduction AC using supra-aural earphones or insert earphones and by bone conduction BC . 4. Describe the types of maskers used for pure-tone and speech testing. 5. Define effective masking EM and how the maskers are calibrated and used with the audiometer. 6. Describe the occlusion effect OE and why this needs to be considered when masking for BC. 7. Describe two advantages of insert earphones over supra-aural earphones as they relate to masking. 8. Define what is meant by a masking plateau and how much of a plateau is appropriate. Discuss why the width of the plateau is smaller when there is a potential bilateral moderate conductive loss. 9. Define overmasking and masking dilemma and recognize situations in which these may occur. 10. Apply the specific steps for AC and BC masking using the plateau method for a variety of unmasked audiograms. 11. Apply the rules for determining if masking is needed for speech testing and select adequate amounts of maskers for speech testing. 177 178 AUDIOLOGY SCIENCE TO PRACTICE The process of putting noise called a masker into the non-test ear NTE while measuring responses from the test ear TE is called masking or clinical masking . The threshold obtained in the TE is called the masked threshold and implies that the masker was delivered to the NTE. In order to be able to deliver a masker into the NTE a two-channel audiometer is needed so that the test sound tones or speech can be routed to the TE .