Download Evaluation of "Noise Notches" from 744,553 Audiogram Pairs

Evaluation of “Noise Notches” from 744,553 Audiogram Pairs
Richard H. Wilson and Rachel McArdle
1
2
VA Medical Center, Mountain Home, Tennessee and East Tennessee State University, Johnson City
2
2
Bay Pines VA Healthcare System, Bay Pines, Florida and University of South Florida, Tampa
1
20
10
+
47
50
.5
.5
to
45
40
LE
16
LE
RE
RE
8
0
LE n = 7,2 5
RE n = 7,105
40 80s
LE n = 385
RE n = 37
0s
LE
RE
16
0
8
10
0
20
80
(5,133)
100
50 Years
40 Years
(46,620)
20
(94,951)
40
(12,016)
60
(25,942)
80
100
0
60 Years
70 Years
20
40
(171,849)
(137,883)
60
(38,221)
80
(15,573)
+
50
.5
42
0
to
NOTCH DEPTH (dB)
+
50
47
.5
.5
42
.5
1
45
10
to
4,247
5,133
40
(40)
12,016
60
(50)
25,942
80
38,221
100
(113,441)
(70)
15,573
(80)
(90)
7,105
379
(9,561)
(7,105)
500 1000 2000 4000 8000
(379)
250
500 1000 2000 4000 8000
FREQUENCY (Hz)
100
0
UNNOTCHED
10
20
(20)
(30)
35,286
26,346
30
(40)
46,620
40
90
5
2.
90 Years
80 Years
90
80
to
AGE DECADE (YEARS)
20-90
70
70
40
90
4
37
80
(4,247)
250
60
60
to
70
8
.5
60
(26,346)
80
(20)
(30)
(60)
50
35
50
12
32
40
30 Years
(35,286)
60
0
(50)
94,951
(60)
171,849
(70)
(80)
(90)
137,883
113,441
9,561
100
250
500
1000
2000
4000
FREQUENCY (Hz)
8000
The 4000-Hz notch data from 744,553 participants can be summarized as follows:
• Only 22.9% of the participants exhibited a 4000-Hz notch in at least one ear.
• Unilateral notches were more prevalent than bilateral notches.
• Unilateral LE, unilateral RE, and bilateral notches had roughly the same prevalence
with LE notches slightly more prevalent than RE notches.
• The prevalence of notches maximizes in the 40-50 year decades, decreasing
substantially in the 70-90 year decades.
• Unilateral notches are more prevalent than bilateral notches at the shallower notch
depths, whereas just the reverse is observed at the deeper notch depths.
• Bilateral notches on average are several decibels deeper than unilateral notches.
• The LE and RE notch depths are about the same with mean depths of ~23 dB.
• The distributions of notch depths vary as a function of age with skewed distributions
at the age extremes and more normal distributions in the 40-60 year decades.
REFERENCES
20
50
16
to
40
20
.5
Figure 6. Histograms of the
percent of unilateral RE (shaded)
and bilateral RE (stripes) 4000Hz notched audiograms for the
for nine notch depths (unilateral
RE, n = 56,885; bilateral RE, n =
51,731).
60
20 Years
40
0
40
NOTCH DEPTH (dB)
24
NOTCHED
30
to
to
to
to
10
.
12
20
+
5
50
42
.5
.5
22
.5
to
20
to
.
12
30
T
IL
A
50
50
100
LE
IL
A
B
IL TE
A
TE RA
R L
A
L
A
T
60
40
RE
N
70
30
42
to
37
.5
.5
35
30
25
to
32
.5
to
27
.5
to
22
.5
to
17
24
U
RIGHT EAR
20
LE n = 15,722
RE n = 15,573
70s
The distribution of the RE notch depths for the unilateral and bilateral
notches are illustrated in Figure 6.
0
30
NOTCH DEPTH (dB)--LEFT EAR
32
10
20
HEARING LEVEL (dB) (ANSI, 2004)
40
40
T
IL
A
B
LE n = 38,484
RE n = 38,221
60s
27
100
0
to
AGE DECADE (YEARS)
90
8
.5
80
LE RE
32
IL
A
N
30
80
16
5
IL
Figure 3. Histograms for the eight
age categories of the percent of
notches present unilaterally in the
target ear (stripes) versus present in
the target ear when the notches were
present bilaterally (shaded). LE, n =
113,818; RE, n = 108,616.
40
LE n = 26,785
RE n = 25, 42
50s
LE RE
24
U
50
24
32
T
60
10
Figure 8. Mean RE notched (filled
symbols) and unnotched (open
symbols) audiograms for the eight
age groups. The gray symbols are
the average audiogram for the two
groups in each panel. The numbers in parenthesis indicate the
number of participants in each
group.
32
to
70
LE n = 13,565
RE n = 12,016
40 40s
25
70
RE
0
30
LEFT EAR
10
20
LE
22
60
RE
8
PERCENT OF NOTCHED AUDIOGRAMS
80
20
0
16
Figure 5. Histograms for the
eight age categories of the
percent of LE (stripes) and RE
(shaded) 4000-Hz notched
audiograms for the for nine
notch depths.
30
LE n = 6,074
RE n = 5,133
30s
24
Figure 3 depicts the distribution of unilateral and bilateral notches by
age decade. Overall, of the 170,703 audiogram pairs with a notch, there
were:
• 113,818 (15.3%) notched LE audiograms, and
• 108,616 (14.6%) notched RE audiograms.
40
LE
32
to
50
LE n = 5,507
RE n = 4,247
.5
40
20
40 20s
.5
AGE DECADE (YEARS)
17
30
to
20-90
0
20
15
55
4,
74
90
40
80
32
70
to
60
50
NOTCH DEPTH (dB)
30
50
to
.5
12
22
.5
40
10
0
PERCENT OF NOTCHED AUDIOGRAMS
3
0
94
9,
6
12
0,
54
6
15
3,
45
0
21
0,
07
3
12
0,
89
36
58
,6
79
30
y = 11.5414 + 0.5553x
The mean RE audiograms by age decade are shown in Figure 8 for
the notched group, the unnotched group, and the two groups
combined. The RE audiograms are redrawn in Figure 9 and grouped
by notch category.
0
AU
20
5000
8
20
0
,4
20
60
RESULTS - - Audiograms
16
10
30
10000
24
to
5
15000
31
0
Figure 7. A bivariate illustration of
the notch depth (dB) for the RE
(ordinate) and LE (abscissa) of the
51,731 individuals with bilateral
4000-Hz notches. For graphic clarity (1) the data points were jittered
randomly using an additive algorithm from -2.4 dB to 2.4 dB in 0.05
dB steps, and (2) only every tenth
data point is shown. The linear
regression reflects the 51,731
notch pairs (R2 = 0.3).
LE RE
32
LE
RE
The bivariate plot in Figure 7 shows the overall notch depth of the
individual participants for the LE (abscissa) and the RE. (ordinate).
40
15
10
20000
33
20
PERCENT OF NOTCHED AUDIOGRAMS
15
25000
LE and/or RE NOTCHED
B
20
NUMBER OF PARTICIPANTS
PERCENT OF PARTICIPANTS
Figure 1. The number of
participants in each age year
(circles) and a histogram of
the percent of participants
in each of the eight age decades. There were 744,553
participants.
25
,5
40
PERCENT OF NOTCHED AUDIOGRAMS
30000
30
39
60
NOTCH DEFINITION & INCLUSION CRITERIA
The audiometric notch was defined when the thresholds at 2000 Hz
and 8000 Hz were both minimally at hearing levels 10-dB lower than
(better than) the threshold at 4000 Hz. Each participant had to have
measurable thresholds in both ears at 2000, 4000, and 8000 Hz. This
criterion reduced the participants to 744,553, which is about 75% of
the original pool. The distribution of ages is plotted in Figure 1.
Figure 4. Histograms of the
percent of LE (stripes) and RE
(shaded) 4000-Hz notched
audiograms for the for nine
notch depths (LE, n = 113,818;
RE, n = 108,616).
UNNOTCHED
80
The distribution of notch depths is shown by ear in Figure 4 and is parsed
by age decade in Figure 5.
• The mean depth for the 113,818 LE notches = 23.1 dB (SD = 9.5 dB).
• The mean depth for the 108,616 RE notches = 23.4 dB (SD = 9.5 dB).
For both ears, the low-frequency side of the 4000-Hz notch was about twice
as deep as the high-frequency side of the notch
• 4000 Hz threshold minus 2000 Hz threshold = 30-dB (SD = 16 dB), and
• 4000 Hz threshold minus 8000 Hz threshold = 16.5-dB difference (SDs = 8 dB).
N
The purpose of the current study was to extend the previous report on
3430 veterans to a substantially larger sample of audiograms. This goal
was accomplished with audiometric data from 1,000,001 veterans that
were archived at the VA Denver Acquisition and Logistics Center (DALC).
Figure 2. The percent of participants
in each age group who had no 4000Hz audiometric notch (squares) or a
LE and/or RE 4000-Hz notch (pluses)
are shown. The latter category is
parsed into three subgroups: a unilateral LE 4000-Hz notch (Xs), a unilateral RE 4000-Hz notch (circles), and
bilateral 4000-Hz notches (AU, triangles). The number of participants
in each age group is indicated at the
top of the graph.
100
U
PURPOSE
The notch prevalence by age decade is shown in Figure 2. Of the
744,553 audiogram pairs:
• 573,850 (77.1%) did not have a 4000-Hz notch in either ear, and
• 170,703 (22.9%) had a 4000-Hz notch in at least one ear.
• 51,731 (6.9%) had notches in both ears,
• 62,088 (8.3%) had a notch only in the LE, and
• 56,884 (7.6%) had a notch only in the RE.
PERCENT OF PARTICIPANTS
Air-conduction audiograms with 3000-, 4000-, and/or 6000-Hz thresholds at
higher hearing levels than the adjacent 2000 and 8000-Hz thresholds are
referred to as notched audiograms. Since the initial observations of the
notched audiograms, noise exposure has been the designated causal factor
(Fowler, 1928: Drury, 1929; Ciocco, 1932; Wever, 1942). Evidence from
animal and human studies has led many investigators to question whether
or not noise exposure is the sole contributing factor to the notched
audiogram (Loch, 1943; Lehnhardt, 1967; Hunter-Duvar and Elliott, 1973;
Cooper and Owen, 1976; Clark and Bohne, 1978; Sataloff, 1980; Humes,
1984; Henderson et al, 1993; Murai, 1997; Luxon, 1998; Committee on
Noise-Induced Hearing Loss, 2006; Talaska and Schacht, 2007; Nondahl et
al, 2009). Additionally, notched audiograms are reportedly associated with
individuals who have no marked history of noise exposure; conversely,
some individuals with a substantial history of noise exposure exhibit no
evidence of a notched audiogram (Luxon, 1998; Osei-Lah and Yeoh, 2010).
Intuitively, because noise exposure typically occurs in a free or sound field,
it is reasonable to expect both ears to be equally affected by noise
incidences. This line of reasoning may not, in fact, be the case. Recent
observations indicate that it is more common to observe unilateral
high-frequency notches than bilateral high-frequency notches (Gates et al,
1999; McBride and Williams, 2001a; Phillips et al, 2010; Osei-Lah and Yeoh,
2010). A recent study from our laboratory substantiated this observation
with data from 3430 veterans (Wilson, 2011). In that study, notched
audiograms were observed in 40.6% of the participants in at least one ear
with 15.4% having bilateral notches, 28.8% LE notches, and 27.1% RE
notches. Thus, unilateral 4000-Hz notches were almost twice as prevalent
as bilateral 4000-Hz notches.
SUMMARY
RESULTS - - Notch Depth Cont.
RESULTS - - Notch Depth
HEARING LEVEL (dB) (ANSI, 2004)
RESULTS - - Prevalence
INTRODUCTION
NOTCH DEPTH (dB)--RIGHT EAR
1
Figure 9. Mean RE notched (top
panel) and unnotched (bottom
panel) audiograms for the eight
age groups (indicated in parentheses). The adjacent numbers
are the number of participants in
each group. (n = 108,616
notched; n = 625,937 unnotched).
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ACKNOWLEDGEMENTS
Appreciation is extended to the audiologists throughout the Department of Veterans Affairs
facilities who share in contributing to this manuscript and to Pam Urrutia, Kevin Quitmeyer,
and Mary Ann Blumenthal from the Denver Acquisition and Logistics Center who extracted
the archived data. The Rehabilitation Research and Development Service, Department of
Veterans Affairs supported this work through the Auditory and Vestibular Dysfunction
Research Enhancement Award Program (REAP), and a Senior Research Career Scientist award
to the first author and through a Career Development Award to the second author. The
contents of this poster do not represent the views of the Department of Veterans Affairs or
the United States Government. [email protected]