Use of laser in diagnosis of hearing disorders

number: 
2771
English
Degree: 
Author: 
Niaam Khalid Hameed Majeed
Supervisor: 
Dr. Munqith S. Dawood
year: 
2012
Abstract:

Hearing loss is a common problem that can occur at any age and makes verbal communication difficulties. The hearing loss may be caused by a pathology in one or more sections of the human ear. This work concentrates on the study of the dynamics of eardrum membrane by using laser interferometric technique as a hearing diagnostic tool.The experimental and mathematical study of how the changes in membrane homogeny and it's physical properties can affect its vibration in response to the impact of the sound waves are achieved in this study. A Michelson laser interferometer was used in the practical study part to measure the frequency response of loudspeaker membrane and rabbits eardrums. A mathematical model for circular drum membrane vibration was used also to simulate the eardrum membrane vibrations.The results showed a similarity in shapes of the response curves over the presented frequencies range (500 – 3500Hz) for both of the loudspeaker membrane and the rabbit eardrum in normal cases. The loudspeaker membrane response loose it's linearity with the input frequencies due to some changes in the physical properties of its surface. The laser interferometer is a reliable method for measuring eardrum vibrations.