Welch Allyn TM286 Directions For Use Manual page 33

Directions for Use
2. Familiarize the individual with the test procedure by presenting a tone of 40 dB HL at
1000 Hz.
3. Decrease the intensity in 10 dB steps until the person no longer responds or until you
reach 0 dB HL.
4. When you believe the individual understands the procedure (i.e., raise your hand/
finger when you hear a tone) proceed with the test.
5. Starting at the desired test frequency, present the tone for a period of one or two
seconds.
6. If a response is indicated,
a. Decrease the intensity of this same test frequency by 10 dB and present the tone
b. If no response is indicated, increase the intensity by 5 dB. Present the tone again.
c. If no response is indicated, increase the intensity by another 5 dB.
d. If a response is indicated, this is the second time that the individual responded to
7 . Repeat this test sequence for each frequency to be tested.
8. When the thresholds have been obtained for all the desired frequencies, select the
other ear and repeat the sequence. Note that the display changes to a new screen for
storing the second ear's results. The test protocol follows a down 10 dB and up 5 dB
sequence to establish threshold level.
Automatic Hearing Level
The Automated Hearing Level Procedure (Auto HL) allows the patient to control the
evaluation using the response button. The software determines the presentation level of
the stimulus based on the Hughson-Westlake Threshold estimation procedure. The
patient should be instructed to hold the button down when s/he hears the tone and
release the button when the tone goes off. In this procedure, the stimulus level is
decreased 10 dB each time the patient presses the button and increased by 5 dB when
the button is not pressed. The TM286 will present the stimulus and increase or decrease
the intensity of the stimulus based on the patient response. The TM286 response/no
response stimuli and determines the hearing threshold based on the data.
Theory of Operation
The following points describe the stimulus presentation patterns and patient response
validity:
1. The stimulus on-time is fixed at 1.5 seconds.
2. The Inter-stimulus interval is randomized between 3 and 5 seconds.
again for one to two seconds.
the same intensity level. Repeat the sequence of down 10 dB and up in 5 dB
increments to determine if a correct response is detected at the same intensity
level. The threshold is considered to be the minimum level at which a response
has occurred two out of three times. Press the
level is indicated on the screen above the test frequency to signify that the
threshold level for that frequency has been reached. Note that the appropriate
symbol (0 = right, X = left) appears at the correct intensity level where the
threshold was determined.
Operation
M +
button when this intensity
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