Post on 25-Feb-2016
description
transcript
Preliminary Analysis of the ChinchillaBlast Overpressure Data
William J. MurphyAmir Khan
Peter B. ShawHearing Loss Prevention Section
Division of Applied Research and TechnologyNational Institute for Occupational Safety and Health
September 29,2008
The results reported in this paper represent the opinions of the authors and are not representative of the policies of the
National Institute for Occupational Safety and Health.
2
Outline Summary of Exposures
Spectrum Interstimulus Interval Level
Exposure Metrics MilStd 1474D LAeq8hr Unprotected AHAAH Warned & Unwarned Pfander Smoorenburg
3
Statistical Analysis of BOP Data
Statistical model for effects threshold Linear Mixed Effects Models Statistical Fits
Questions to consider for the analysis Trading Ratios? Log(AHAAH) Frequency Dependency
4
101
102
-70
-60
-50
-40
-30
-20
-10
0
10
Frequency (kHz)
Wel
ch P
ower
Spe
ctra
l Den
sity
Est
imat
eP
ower
/freq
uenc
y (d
B/H
z)
Conventional Shock Tube Nonreverberant
5
101
102
-45
-40
-35
-30
-25
-20
-15
-10
-5
Frequency (kHz)
Wel
ch P
ower
Spe
ctra
l Den
sity
Est
imat
eP
ower
/freq
uenc
y (d
B/H
z)
Fast Acting Valve
6
101
102
-40
-35
-30
-25
-20
-15
-10
Frequency (kHz)
Wel
ch P
ower
Spe
ctra
l Den
sity
Est
imat
eP
ower
/freq
uenc
y (d
B/H
z)
Spark Gap Generated Impulse
7
10-1
100
101
-70
-60
-50
-40
-30
-20
-10
0
10
Frequency Hz
Wel
ch P
ower
Spe
ctra
l Den
sity
Est
imat
eP
ower
/Fre
quen
cy (d
B/H
z)
Narrow Band Impact Noises
260 Hz775 Hz1025 Hz1350 Hz2450 Hz3550 Hz
8
500
2000
8000
140
150160
170
180
190-10
0
10
20
30
40
50
60
70
80
90
Frequency (Hz)
Temporary Threshold Shift vs MIL-STD-1474D
MIL-STD-1474D (dB)
Tem
pora
ry T
hres
hold
Shi
ft (d
B)
9
500
2000
8000
120
140
160
180
200-10
0
10
20
30
40
50
60
70
80
90
Frequency (Hz)
Temporary Threshold Shift vs Pfander
Pfander (dB)
Tem
pora
ry T
hres
hold
Shi
ft (d
B)
10
500
2000
8000
140
150
160170
180
190-10
0
10
20
30
40
50
60
70
80
90
Frequency (Hz)
Temporary Threshold Shift vs Smoorenburg
Smoorenburg (dB)
Tem
pora
ry T
hres
hold
Shi
ft (d
B)
11
500
2000
8000
100
102
104
106
-10
0
10
20
30
40
50
60
70
80
90
Frequency (Hz)
Temporary Threshold Shift vs Unwarned AHAAH
Unwarned AHAAH (ARUs)
Tem
pora
ry T
hres
hold
Shi
ft (d
B)
12
500
2000
8000
100
105
-10
0
10
20
30
40
50
60
70
80
90
Frequency (Hz)
Temporary Threshold Shift vs Warned AHAAH
Warned AHAAH (ARUs)
Tem
pora
ry T
hres
hold
Shi
ft (d
B)
13
500
2000
8000
100
110
120130
140
150-10
0
10
20
30
40
50
60
70
80
90
Frequency (Hz)
Temporary Threshold Shift vs LAeq8
LAeq8 (dB)
Tem
pora
ry T
hres
hold
Shi
ft (d
B)
14
5001000
20004000
8000
150
160
170
180
-10
0
10
20
30
40
50
60
Frequency (Hz)
Permanent Threshold Shift vs MIL-STD-1474D
MIL-STD-1474D (dB)
Per
man
ent T
hres
hold
Shi
ft (d
B)
15
5001000
20004000
8000
120
140
160
180
200-10
0
10
20
30
40
50
60
Frequency (Hz)
Permanent Threshold Shift vs Pfander
Pfander (dB)
Per
man
ent T
hres
hold
Shi
ft (d
B)
16
5001000
20004000
8000
150
160
170
180
-10
0
10
20
30
40
50
60
Frequency (Hz)
Permanent Threshold Shift vs Smoorenburg
Smoorenburg (dB)
Per
man
ent T
hres
hold
Shi
ft (d
B)
17
5001000
20004000
8000
100
105
-10
0
10
20
30
40
50
60
Frequency (Hz)
Permanent Threshold Shift vs Warned AHAAH
Warned AHAAH (ARUs)
Per
man
ent T
hres
hold
Shi
ft (d
B)
18
5001000
20004000
8000
100
102
104
106
-10
0
10
20
30
40
50
60
Frequency (Hz)
Permanent Threshold Shift vs Unwarned AHAAH
Unwarned AHAAH (ARUs)
Per
man
ent T
hres
hold
Shi
ft (d
B)
19
5001000
20004000
8000
100
110
120
130
140
150-10
0
10
20
30
40
50
60
Frequency (Hz)
Permanent Threshold Shift vs LAeq8
LAeq8 (dB)
Per
man
ent T
hres
hold
Shi
ft (d
B)
20
Applied linear mixed effects regression models to compare the different metrics Fixed effects: metric and frequency and log
transformations of these variables Random effects: subject and exposure code
(takes into account correlated nature of data for given subject and exposure code)
Statistical Analysis of Chinchilla Data
21
PTS Data Analysis Indep. Variables (fixed
effects) AIC BIC
MIL STD 1474D + frequency 51279.99 51320.97
LAeq8+ frequency 51214.76 51255.75
warned AHAAH + frequency 51263.38 51304.36
unwarned AHAAH + frequency
51236.62 51277.6
Pfander + frequency 51253.09 51294.07
Smoorenburg + frequency 51258.78 51299.77
25
TTS Data Indep. Variables (fixed effects) AIC BIC
MIL STD 1474D + frequency 35060.91 35098.91
LAeq8+ frequency 34956.34 34994.34
warned AHAAH + frequency 35068.4 35106.41
unwarned AHAAH + frequency 35055.47 35093.47
Pfander + frequency 35021.17 35059.17
Smoorenburg + frequency 35031.85 35069.85
29
Preliminary Findings LAeq8 provides the best fit to the TTS data
of the competing metrics. Unwarned AHAAH tends to provide the
best fit to the PTS data after a log(AHAAH) transformation.
30
Discussion Topics Utility of providing a transformation of
AHAAH estimates. Sampling Rate questions for all models. Frequency dependency for the models.
AHAAH model may have predictive capability for frequency that other models do not.
Should we pursue finding best trading ratios? 10 log(N), 5 log(N), x log(N)
31
Discussion topics
What outcome variable is the most useful here?
Are we interested in developing a better model to fit the data or just existing models?