GSi 61 - Tone Decay Test

Patients with retrocochlear pathology of the eighth nerve exhibit a rapid “abnormal auditory
adaption” or a “temporary threshold drift” in response to a continuous pure tone
presentation.
Carhart Tone Decay Test (1957)
Establish the patient’s hearing threshold for the test ear using earphones or insert phones
and selecting a pulsed tone.
Instruct the patient to depress the handswitch as soon as a tone is heard, and to release the
handswitch only when the tone becomes inaudible.
Begin the test with a continuous tone. Set the intensity for the selected channel to 0 dB SL
(or 20 dB SL to present an easier listening task). The Interrupt pushbutton may be selected
or the Tone bar may be manually depressed for the duration of the test.
As soon as the patient responds, begin timing by pressing the Start pushbutton of the
scorer/timer. Record the number of seconds the tone sustains audibility with the Timer on
the front panel of the GSI 61 (F17).
If the tone becomes inaudible before the minute criteria is met, without interrupting the tone
presentation, raise the intensity in 5 dB steps until the tone is heard for a full minute.
Reset the timer at each increase in intensity level. Continue this procedure until the tone is
heard for a full minute, or until an intensity of 40 dB SL is reached.
Tone Decay
Test
1.
2.
3.
4.
5.
6.
Grason-Stadler GSI
®
61 CLINICAL AUDIOMETER
Lombard or Voice-Reflex Test
The Lombar
d
Tes
t
is
b
ased on the
p
rinciple tha
t
individuals monito
r
thei
r
vocal intensity
b
y
means of auditory feedback. It is normal for individuals to speak more loudly when
exposed to a background of masking noise (approximately 16 to 20 dB above the threshold
for the noise).
The patient is given a clearly typed paragraph to read aloud into the talk back microphone.
Put on the monitor headphones (monitor speaker may also be selected). Adjust Channel
and Talk back monitor knobs to appropriate levels.
Select Speech Noise as the input signal on Channel 1. Routing should be Left/Right. The
output is presented through the earphones or sound field speakers. Channel 2 is not active
during this test.
Signal to the patient to begin reading. With the Channel 1 attenuator set to an intensity of
0 dB HL, gradually increase the intensity of the noise level.
N
ote the level of masking at which the patient’s voice becomes more intense and compare
this level with the de
g
ree of supposed
p
atien
t
hearin
g
loss.
1.
2.
3.
4.
5.
4-8
1761-0100 Rev. B