Tone decay is a legacy test on the GSI AudioStar Pro and the GSI Pello that evaluates abnormal adaptation to sound caused by a retrocochlear pathology, such as an acoustic neuroma. This is a subjective evaluation that can add diagnostic value to an audiometric evaluation. The general procedure is to measure the ability to perceive and maintain a pure tone presented continuously, for about one minute. Patients with retrocochlear pathology of the eighth nerve exhibit a rapid “abnormal auditory adaption” or “temporary threshold drift” in response to a continuous pure tone presentation.



Presentation Levels

Establish the patient’s hearing threshold for the test ear using earphones or insert phones using a pulsed tone. Set the level for the selected channel to 0 dB SL (or 20 dB SL to present an easier listening task). The Interrupt push button may be selected, or the Present bar may be manually depressed for the duration of the test.


Test Instructions

“Instruct the patient to depress the hand switch as soon as a tone is heard, and to release the hand switch only when the tone becomes inaudible.”

Tone Decay Test Procedure with AudioStar Pro and Pello

1. Select Tone Decay from the More Tests Menu. 

2. Present the continuous tone at the selected level.

3. When the patient responds by pressing the patient response button, the timer will start. The timer may be manually started by pressing the Start push button of the scorer/timer.

4. When the patient releases the patient response button, the timer will pause. If the patient pushes the response button again, the timer will resume.

5. Record the number of seconds the tone sustains audibility. 

6. If the tone becomes inaudible before the minute criteria is met, without interrupting the tone presentation, raise the level in 5 dB steps until the tone is heard for a full minute.

7. Reset the time at each increase in level. Continue this procedure until the tone is heard for a full minute, or until a level of 40 dB SL is reached.


Interpreting Tone Decay Test Results

A normal response should be maintained for about a minute of stimulation. If the patient responds for the full 60-second test period, the result is negative. If the patient fails to respond for the full 60 seconds, the result is considered positive for eighth-nerve site.