Special Test(TDT,SISI)

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Hearing Aid Centre Chennai Special Test(TDT,SISI)

Tone Decay Test (TDT)
The tone decay test (also known as the threshold tone decay test or TTDT) is used to detect and measure auditory fatigue.
In people with normal hearing, a tone whose intensity is only slightly above their absolute threshold of hearing can be heard continuously for 60 seconds. The tone decay test produces a measure of the “decibels of decay”, i.e. the number of decibelsabove the patient’s absolute threshold of hearing that are required for the tone to be heard for 60 seconds. A decay of between 15 and 20 decibels is indicative of cochlear hearing loss and the decay more than 25 decibels is indicative of damage to the vestibulocochlear nerve.

SHORT INCREMENT SENSITIVITY INDEX TEST (SISI)
The SISI test is still widely used to determine cochlear pathology in patients. This test is based on a phenomenon known as recruitment (abnormal loudness growth).

Clinical Procedure for TDT

  1. The patient will be made to relax on a reclining chair, with earphones attached.
  1. A tone at the frequency of 4000 Hertz will be passed for 60 seconds at an intensity of 5 dB above the patient’s absolute threshold of hearing.
  1. If the patient stops hearing the tone before 60 seconds, the intensity level is increased by another 5dB. This procedure will be repeated until we reach the decibel level where the tone can be heard for the full 60 seconds.
  1. The highest intensity will be recorded if no decibel level can be found where the tone can be heard for the full 60 seconds.
  1. Thus the resultant measure is given as the decibels of decay.
Hearing Aid Centre Chennai Special Test(TDT,SISI)
Hearing Aid Centre Chennai Special Test(TDT,SISI)

Clinical Procedure for SISI

Hearing Aid Centre Chennai Special Test(TDT,SISI)

  1. The patient will be made to relax on a reclining chair, with earphones attached.
  1. A pure tone at an intensity of 20dB will be passed into the ear.
  1. A small increase in intensity is superimposed upon the steady state tone at periodic intervals. The size of intensity increment varies form 5dB-1dB.
  1. The ability to detect the 1 dB increments is present only in patients with cochlear pathology and is absent in patients with normal hearing or with a conductive hearing loss.

Average Testing Time

For an effective Special Test(TDT,SISI) testing session it fetches around 45mins to 1hr for completion. Clinical reports will be provided immediately after test.

Hearing Aid Centre Chennai Special Test(TDT,SISI)
Hearing Aid Centre Chennai Special Test(TDT,SISI)

 

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