Types of Hearing Loss testing - Dr. Sreenivasa Murthy T. M

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Hearing tests are of various types, we classify tem as subjective ad objective, subjective tests are those tests which will be dependent only the use, that is he person who is undergoing the test his or her response will determine the end result and the objective tests doesn't depend on the subject, that is irrespective of whether the subject responds to the stimulus that the manner gives, we will be able to tell whether the patient is hearing or not hearing. The commonly performed subjective test is free field audiometry in children, which cannot give us proper responses in an age group that is less than 2 years of age. In this what we do is the free field audiometry. In this we give the sound either from the left side or the right side and we see whether the child is responding to those sounds by turning their head or not. So that is a rough estimate. It is not easy to tell what is the exact amount of hearing. But it is a screening tool like device. Then there is a pure tone audiometry, which is a purely subjective test, which would require some amount of cooperation form the patient or the subject who is undergoing the test. They have to be intelligent enough to tell them what the examiner wants them to respond and that way they will be able to assess hearing by giving stimulus of various decibels and various frequencies and then chart it put on a graph. This is the most commonly performed audiometry test. It is a pure tone audiometry. Other than that the middle ear functions and the acoustic pathway reflux can be tested by tympanometry and acoustic reflex, this gives us information in the middle ear as well as movement in the ear drum, as well acoustic reflux pathway is intact or has it been interfered with. Other than this there are some other tests like brainstem evolved response audiometry which is an objective test. In this test what we do is we connect the patient to a computer and we give a stimulus to the ear in the form of a noise and we trace a pathway of the entire auditory pathways on the computer. So this is something like the EEG or the electroencephalogram which will chart out the activity in the brain and here the activity in the brain is charted out by the auditory pathway. So this is what is commonly done where we will not able to assess hearing in people who are not able to respond well or who are young and who cannot respond to what we need this is called as BERA. There are other test called as ASSR and other tests which are also objective, as a screening objective hearing, we use what is called as OAE or Otoacoustic Emissions.