Gaps in Noise (GIN) Test –Normative Data

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ABSTRACT
Temporal resolution is a sub categorization
of temporal processing.
Temporal resolution refers to the ability
of the auditory system to identify
rapid changes in the envelope of a
sound stimulus over time1 .
The GIN test (Musiek 2003) is one
such test to detect gap detection (GD)
abilities. The Gap detection threshold
(GDT) is defined as the shortest
duration of gap within a sound that
a person can detect. This test has
been found to be useful for assessing
temporal resolution2,3,4 .
The gap detection studies have
often been applied to patients with
cortical lesions2 . Mu-siek et al (2005) 5
have included few brainstem pathology
patients (n=9) in their study and
stressed the significance of administering
gap detection tests on more
number of such patients. The GIN test
is thus a valuable tool in identifying
temporal resolution deficits in cortical
as well brainstem lesions.
* dept. of Speech pathology and Audiology,
AiMS, Kochi.
** dept. of Speech pathology and Audiology,
niMHAnS, bangalore
***dept. of Epidemiology, niMHAnS, bangalore
Gaps in Noise (GIN) Test –Normative Data
G. Prem*, N.S. Shankar**, N. Girish***
introduction: The detection of gaps in noise is one of the temporal resolution abilities of the auditory system. The detection abilities using
the Gaps In Noise (GIN) test is of great utility in assessing patients with cortical and brainstem lesions. Establishing a normative database
in Indian context on this test is of utmost importance for identifying the pathological group.
Aim: To establish a normative database for GIN test in Indian population and to ascertain if any ear, gender and age group differences exist.
Methodology: The GIN test was administered on 100 normal hearing subjects ranging in age from 17-60 years (52 males and 48 females).
Two indices were used in our study-approximate threshold measurement or gap detection threshold (GDT) and total percentage score
(TPS). The subjects were grouped into two group’s viz., Group I: 17-40 years and Group II: 41-55 years.
Results: Mean and standard deviation (SD) for both GDT and total percentage score were estimated: right ear: 5.82 msec (1.27) and left
ear: 5.84 msec (1.11). The mean TPS in our study was right ear: 62.99% (8.48) and left ear: 63.25% (7.78). The results were statistically
treated to determine ear, gender and age group differences.
discussion: No significant differences were observed in any of these variables for both GDT and total percentage score.
Given the diagnostic significance
of GIN test, establishing a normative
database is of paramount importance
for accurate delineation between
normal and abnormal temporal resolution
abilities in subjects. It is also
of immense value to determine any
ear, gender and age group differences
in normal hearing subjects before
administering and interpreting the
test results on clinical group. These
findings are of utmost importance
and can be considered as a gold
standard to which the test results
administered on patient population
can be compared. In India such a
data base is not available for clinical
neuroaudiological application of the
GIN test and hence the present study
was undertaken.
OBJECTIVES OF THE STUDY
To establish a normative database
for GIN test in Indian population and
to ascertain any ear (right and left),
gender (male and female) and age
group (young and middle age) differences
on test performance in normal
hearing subjects.
METHODOLOGY
One hundred subjects constituted
the study group. The age of the
Vol. 8, No: 1
Jan - Jun 2012. Page 1 - 44
Conclusion: The database developed can be of great utility in assessing temporal resolution skills using GIN test in Indian context.
subjects ranged from 17-60 years
(52 males and 48 females). All
subjects demonstrated pure tone
thresholds of 20 dB HL or better
for the octave frequencies of 250
to 8000 Hz bilaterally. Subject
inclusion criteria included negative
histories for audiologic, otologic and
neurologic involvement. The subjects
were grouped into two group’s viz.,
Group I: 17-40 years and Group II:
41-55 years.
The GIN test was administered
and scored as per the set criteria
(Musiek 2003). The stimulus was
presented at 50 dB sensation level (SL)
above puretone average (PTA) of 500,
1000 and 2000 Hertz. The indices
used were Gap Detection Threshold
(GDT) and Total Percentage Score
(TPS).
description of the test and
scoring
The GIN is composed of 4 different
lists designated as Test 1, Test
2, Test 3 and Test 4. The four lists
contain a series of up to 36 different
6 second white noise segments. Each
of the white noise segments contain
anywhere from 0 to 3 gaps of silence.
The duration of the silence gaps are

Amrita Journal of Medicine
either 2, 3, 4, 5, 6, 8, 10, 12, 15 or 20 msec with each
silence gap duration occurring six times in each GIN
list. The order of the gap durations is randomized.
Each GIN list contains a total of 60 gaps per list. A five
second gap of silence separates each six second noise
segment. Usually, one list is administered in each ear.
A practice list is provided at the beginning of the test to
ensure that the patient understands the task.
While undergoing the test, the subject needs to listen
for any silence gap that may or may not occur within
each noise burst. As soon as the gap is detected the
subject has to respond by pressing the button.
The GDT was calculated by considering the following
2 criteria:
1) At least 4 out of 6 gaps are correctly identified
2) Performance for longer gap durations is not
worse than 4 out of 6 gaps correctly identified.
The TPS was calculated by dividing the total number
Table 1: gin test performance classified based on ear and gender.
Table 2: gin test performance classified based on age.
Gaps in Noise (GIN) Test –Normative Data
of correct gap durations identified by the total number
of gap durations presented (n=60) multiplied by 100.
False positives were noted. When more than 2 false
positives occurred per ear, it was counted as errors and
sub-tracted from the number of gap durations identified
(Musiek, 2003).
RESULTS
Mean and SD for both GDT and TPS were estimated
(Table 1). Females had a mean GDT of 5.6 (1.086) msec
in the right ear and 5.65 msec (.956) in the left ear.
Males had a mean GDT of 6.02 msec (1.39) in the right
ear and 6.02 msec (1.21) in the left ear. The mean total
percentage score in females in the right ear was 64.92%
(7.37) and 64.7% (8.03) in the left ear whereas; in males
it was 61.21% (9.09) in the right ear and 61.92% (7.36)
in the left ear. No statistical difference was observed
between males and females for both GDT and TPS.
Hence the data between the genders was clubbed to
get a unified index for the right and left ears.
Sex Right gdT R TPS left gdT left TPS
Female Mean 5.6 64.92 5.65 64.70
N 48 48 48 48.0
Std Deviation 1.086 7.372 .956 8.0315
Range 4 32 4 30
Male Mean 6.02 61.21 6.02 61.919
N 52 52 52 52
Std Deviation 1.393 9.097 1.213 7.3664
Range 7 42 6 45.6
Total Mean 5.82 62.99 5.84 63.254
N 100 100 100 100
Std Deviation 1.266 8.479 1.108 7.780
Range 7 43 6 45.6
Coded Right GDT R TPS Left GDT Left TPS
Age
17-40 Mean 5.64 64.10 5.60 64.732
Years N 70 70 70 70
Std Deviation 1.274 8.719 1.095 8.3651
Range 7 43 6.0 45.6
41-55 Mean 6.23 60.38 6.4 5 9 . 8 0 6
Years N 30 30 30 30
Std Deviation 1.165 7.386 0.932 4.7505
Range 3 24 3 21.7
ANOVA revealed no statistically significant difference in GIN test performance between the groups for both GDT
and total percentage score. There was also no statistically significant difference between right and left ear performances
between groups for both indices.
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In order to ascertain the effect of age on GIN test
performance (Table 2), the subjects were divided into
2 groups viz.,
Group 1: 17-40 years of age.
Group 2: 41-55 years of age.
Group 1 subjects had a mean GDT of 5.64 m sec
(SD=1.27) in the right ear and 5.6 m sec (SD=1.1) in
the left ear. Their mean total percentage score in the
right ear was 64.1% (SD=8.72) and 64.73% (SD=8.37)
in the left ear.
Group 2 subjects had a mean GDT of 6.23 m sec
(SD=1.17) in the right ear and 6.4 m sec (SD=. 932) in
the left ear. Their mean total percentage score in the right
ear was 60.38% (SD=7.39) and 59.81% (SD=4.75) in
the left ear.
DISCUSSION
Auditory temporal processing refers to the ability of
the auditory system to identify temporal features of a
sound. Common temporal features include sound envelope
fluctuations (amplitude modulation, frequency
modulation) or starts and stops in ongoing sounds6 .
The main types of auditory temporal processing include
phase locking, gap and duration coding (specialized
neural responses to the onsets and offsets of sound
energy), and coding of prosodic patterns (Pichora-Fullerpaper
presentation, 2000).
The temporal resolution is probably one of the basic
ingredients for speech perception and its assessment
may provide vital information about the neural integrity
of the central auditory nervous system4,7 . It is a valuable
tool in identifying temporal resolution deficits in the
lesions of the central auditory nervous system. To
identify the pathological GIN behavior in patients, it
becomes mandatory to have a normative database.
In the present study the comparison of GIN test
performance between males and females and between
the subjects belonging to the two groups (classified
based on age) did not show any signifi-cant difference
on both the indices. Many investigators have demonstrated
that older subjects may present with increased
GDTs in comparison to younger control subjects8,9,10,11,12 .
Other studies have questioned this finding13 . These
discrepancies may be due to the interaction between
stimulus complexity and age. However, Musiek et al
(2005) 5 opines that since the GIN test uses a simple
stimulus (broadband noise) differences due to age factor
is unlikely. His study reported no significant difference
on GIN test performance of young and middle aged
subjects. He et al (1999) 9 also share similar views while
using broadband noise as stimuli. Lister et al (2002) 3
stated that no significant difference exists between GDTs
obtained for young and middle aged individuals. Our
Gaps in Noise (GIN) Test –Normative Data
study also concurs with these studies. The GDT in our
study (Right ear: 5.82 msec; SD=1.27 and Left ear: 5.84
m sec; SD=1.11) is slightly higher than that of Musiek
et al, (2005)5 (Right: 4.9 msec and Left: 4.8 msec) but
lower than Keith’s (2000)14 study. The mean TPS in our
study is lower (Right ear: 62.99%; SD=8.48 and Left
ear: 63.25%; SD=7.78) than Musieks’ study5 , which
reported 70% bilaterally.
The GDTs obtained on subjects (patients as well
as control group) seems to depend upon the extent
of training imparted to them prior to the actual test.
This is supported by other researchers too5,15 . The
performance on GIN test also depends on the ability
of subjects to understand the instructions as well as to
concentrate and respond accurately throughout the test
duration. All these factors will in turn depend upon the
subjects’ educational background, cognitive capacity
and motivation. Thus, discrepancies observed in the
different studies may be explained. In a clinical situation
it may be difficult to train the patients on this test for a
longer period of time due to their health status, medical
emergencies, cognitive level and short time available
to the clinicians. To offset these factors normative data
on a sizable number with appropriate repre-sentation
from all socio-economic and educational strata becomes
necessary.
CONCLUSION
A database was developed for Normative GIN test by
administering the test on 100 normal hearing subjects.
Values were obtained for both the indices of the test,
GDT and total percentage score. Mean and standard
deviation values for both the indices were calculated.
Test results revealed that there was no statistically
significant difference among the performance of GIN
test between right and left ears, males or females and
also young and middle aged subjects. This normative
GIN Test database was developed on a large number of
subjects (n=100) with different educational, cultural and
cognitive capacities it can be utilized as a normative data
in the clinical assessment of central auditory nervous
system dysfunctions.
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