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Military Noise Environments and Hearing
Protection/ConservationNovember 17, 2000
Military Noise Environments and Hearing
Protection/ConservationNovember 17, 2000
Richard McKinley
Human Effectiveness Directorate
Richard McKinley
Human Effectiveness Directorate
2
Briefing Overview
• Defining the environment/problem– F-22– JSF– Legacy aircraft - F-14, F-15, F-16, F-18, EA-6B
• Personnel exposure requirements
• Integrated Solution
– Technology, training, education, and administrative controls
16
F-22 Acoustics
• F-22 lessons learned– Early measurements dispelled much of the
concerns regarding intense low frequency noise
– Cockpit noise became an issue during return to flight test
– Probable non-linear propagation of noise -shock waves
– Very intense acoustic levels aft of the tail
17
Military Noise Environments
• Approach
– Define current Navy/Air Force noise and vibration exposure standards and requirements
– Baseline current Air Force/Navy operational aircraft vibration and noise environments both cockpit and ground support/maintenance
– Measure vibration and noise from F-119 engine in F-22
– Initiate human exposure effects expansion of limits and/or mitigation studies if required
– Measure vibration and noise on JSF CDA variants
18
F-22 Raptor Near Field NoiseCrew Positioning
• Ground crew personnel locations
Comm Line50 ft Radius
Engine Adjustment position: 150 dBA
exhaust
Crew Chief position: 139 dBA
19
F-16C F100 – PW-229 Mil Power Near-Field Noise
Not to scale
35 ft
Flow Area
124
125
127132
126
133
132
143
145
in dB SPL (Flat) Right Engine
Legend
50 ft
76m
u
u
u
u
u
u
u
30m
43m
41s
7m8m
8m
27m
34m
54m
26s
Allowable exposure timeWith current muff & plugsAllowable exposure timeWith new hpd technologiesU=unlimited
20
F-22 Near-field personnel noise
-150 -100 -50 0 50 100 150 200
Feet
-150
-100
-50
0
50
100
150
200
Feet
120.0
125.0
125.0
125.0
130
.0
135
.0
135.0
140.0
145.0
145.0
150.0
F-22 Right (Mil) 100% ETR - Left Engine 10% ETRNear Field Noise Predictions (SPL in dB)
Flow Field
Note: For general sense of directional characterizationof noise field. Use measured near-field noise locationsfor personnel noise exposure.
145 dB 140 dB 135 dB 130 dB
125 dB
21
F-22 Near-field personnel noise
-150 -100 -50 0 50 100 150 200
Feet
-150
-100
-50
0
50
100
150
200
Feet
120.0
125.0
125.0
130.0
130.0
135
.0
135.0
140
.0 145.0
150.0
150.0
155.0
F-22 Right (A/B) 150% ETR - Left Engine 10% ETRNear Field Noise Predictions (SPL in dB)
Flow Field
Note: For general sense of directional characterizationof noise field. Use measured near-field noise locationsfor personnel noise exposure.
125 dB
135 dB
130 dB
140 dB145 dB
22
F-22 Near-Field Noise 35’ & 50’A/B-150% ETR, Right Engine
Not to scale
35 ft
Flow Area
133
135
139141
138
148
147
153
150
in dB SPL (Flat) Right Engine
Legend
50 ft
8m
240m
24m
30m
191m
761m
480m
121m
15m
4m
4s
13s64s
16s
1.7m
2m
7m
8sAllowable exposure timeWith current muff & plugsAllowable exposure timeWith new hpd technologies
23
F-22 Near-Field Noise 42’ & 100’A/B-150% ETR, Right Engine
Flow Area
A B C D E F G
H I J K L M N O P
42 ft
100
ft
142 142 142 142
142 146 147 147 147 147
in dB SPL (Flat) Right Engine
Legend
51s 51s 51s 51s
51s 20s 16s 16s16s 16s
96m 96m96m 96m
96m38m30m 30m30m 30m
Allowable exposure timeWith current muff & plugsAllowable exposure timeWith new hpd technologies
24
F-18F After-Burner Power - 42' Foul LineMicrophone Position 4
0
20
40
60
80
100
120
140
160
FW
5 8
12.5 20
31.5 50 80 125
200
315
500
800
1250
2000
3150
5000
8000
1250
0
1/3 Octave Frequencies (Hz)
SPL
(dB
re. 2
0uPa
)
25
JSF Personnel NoiseCrew Positioning Challenges
F-18 C Noise Contours
125 dBA125 dBA
Feet
Limit of Existing Limit of Existing Hearing ProtectionHearing Protection
(Safe Duty Exposure)(Safe Duty Exposure)= Danger= Danger
26
AF & Navy Personnel Noise
60
70
80
90
100
110
120
130
140
150
160A
V-8
BE
A-6
B
F-14
A
F-16
(P22
9)F-
18C
F-18
F
JSF
STO
VL
JSF
CV
& C
TO
L
Soun
d L
evel
dB
A
Mil Power A/B Power
Unlimited ExposureLimit 85 dB
Technology Limit(-50dB)
F-18
C
F-14
A
JSF
CV
& C
TO
L
Current Protection(-30dB)
F-16
(P22
9)
F-22
(F-1
19)
F-22
(F-1
19)
Jet Aircraft Near Field NoiseNo Protection @ 30 ft
27
Personnel Noise Requirements
• JSF JORD and Joint Model Spec– Noise exposure for ground/flight deck crew shall
not exceed a daily exposure equivalent to 85 dBA for 8 hrs with a 3 dB/doubling exchange rate
– Normal operations defined as 60 launches and 60 recoveries within a 24 hr period
– Assumes other exposures are less than 85 dBA
• AFOSH 48-19 Hazardous noise exposure– 85 dBA - 8 hrs - 3 dB/doubling
• OPNAVINST 5001– 80 dBA - 16 hrs - 4 dB/doubling– 85 dBA - 8 hrs - 3 dB/doubling
28
Whole Body Noise Exposure
• Legacy aircraft - lessons learned
– Levels at personnel locations up to 150 dB
– Intense acoustic field resonates chest -resonate frequency around 80 Hz
– Other body systems resonate at other frequencies and can be a source of discomfort
29
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 10 20 30 40 50 60 70 80
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 10 20 30 40 50 60 70 80
Perspective on Material Solutions
Number of Launch and Recovery Exposures
Nor
mal
ized
Tim
e W
eigh
ted
Tot
al D
aily
Noi
se E
xpos
ure
With Enhanced-50dB Protective
Gear
With Current-30dB Protective
Gear
DANGERPermanent Hearing
Loss
Typical number of Launches & Recoveries deck personnel are exposed to during duty shift
JSF CV & CTOL A/B F-16 A/BF-18F A/B
JSF CV & CTOL MilEA-6B Mil
JSF STVOL Mil
F-14A A/BF-16 MilF-18C MilAV-8B MilF-14A Mil
F-18C A/B
~1 Launch per 24 hour period results in 100% of the safe allowable noise dose
30 46
JSF A/B catapult operations only expected for full fuel with external stores
DANGERPermanent Hearing
Loss
30
Personnel noise exposure
Noise level vs safe exposure time per AFOSH 48-19
0.1
1.0
10.0
100.0
1000.0
10000.015
0
148
146
144
142
140
138
136
134
132
130
Noise level in dBA
Safe
exp
osur
e tim
e in
m
inut
es
Current muffs & plugs
Proposed hearing protection system
31
Personnel Noise
• Issue:– Today’s hearing protection is not adequate against current
aircraft noise emissions - hearing loss is the #1 disability among retired US Military personnel
– F-22 & JSF personnel noise similar to F-14, F-15, & F-18 (A/B takeoff)
– No technology exists to quiet fighter engines without significant performance losses
• Problem is multifold:– Hearing protection- same technology past ~30years
– Duty requires close proximity to noise source
– Long duty shift, Cumulative exposure time
32
Non-Material Solutions
Policies & Procedures– Crew rotation– Crew relocation– Operating procedures
(e.g., run-up times, etc.)– Flight deck/flight line
improvements (e.g., robotics, telemetry, barriers)
– Training in equipment fit, use, & care
– Disciplined enforcement of protection use– Personal issue engages a responsibility process
33
Near Term Solutions 2001-2002
• Technology– Optimized passive protection: Improved earplugs & earcups w/wo
communication. • Goal: 35-40 dB of attenuation (includes non-material solutions
previously noted, e.g. training)• Required S&T Investment
– Deep insert custom earplugs• Compliant: Marry benefits of custom fit & expandable materials
– Improved noise attenuation earcups/cranial– Field performance metric
• Enabling Research– Materials– Optimal insertion depth (earplug) – Size, shape, seal, location, hygiene– Anthropometry: Identify fit issues and population norms– Field technology performance validation
35
Mid Term Solutions2002-2005
• Technology Development– Improved Passive Cranial– Active Noise Reduction (ANR) Earplug
• Goal: 40 - 50 dB attenuation• Required S&T Investment
– High bandwidth, high intensity ANR techniques• Analog vs digital vs hybrid
– Improve materials, sensors, drivers, anthropometry– Acoustic model of bone/tissue conduction
• Airborne and structural pathways– Low vs. high frequency– Low vs. high intensity
• Tympanic membrane, inner ear structures
36
• Audio signal directly injected into the ear canal for clear communications
• Incorporated into passive noise reduction headset for maximum noise reduction
ACCES Prototype
Active Noise Reduction Earplug
NOISE
SPEECHAUDIO DRIVER
COMM CORD
37
Active Noise Reduction (ANR) Communication Headsets
ANR uses Standing Waves principlenoise anti-noise
38
Far Term Solutions2004-2007
• Technology Development– Active Vibration Control Cranial/Helmet
• Goal: 50+ dB attenuation• Required S&T Investment
– Improve materials, sensors, drivers, anthropometry– Acoustic model of bone/tissue conduction
• Airborne and structural pathways– Low vs. high frequency– Low vs. high intensity
• Tympanic membrane interactions
39
Performance Metrics
• Databases mapping and tracking crew locations and crew performance versus hearing loss are poor and virtually non-existent
– Expand and maintain Air Force’s computerized hearing repository data base
• Mandate use of accepted national standards for characterization and testing
Performance changes need to be measured and tracked as solutions are implemented
40
Proposed Solution Recap• Integrated solution of technology, training, education, and
administrative controls• R&D technologies for a dedicated hearing protection system
improvement program – Custom Fit Deep Insert Earplugs– ANR Earplugs– Improved Passive Cranial– Active Vibration Control Cranial/Helmet– Enabling Research e.g., sensors, models
• Field performance verification/validation• Crew rotation, administrative procedures
41
• Personnel Noise– Current flight-line/deck hearing protection is inadequate
- improved hearing protection is needed TODAY– Some crew member locations should be moved and/or
exposure time limited– Technology solutions to certain functions are being
worked -– Work on engines continue projected effects are small 3-
5 dB and very expensive
– Flight deck/flight line noise levels are systemic– F-22, F-18E/F, & JSF in addition to numerous legacy
aircraft have comparable personnel noise levels/exposures
– Solutions must involve service headquarters, operators, acquisition, scientists/technologists, and service medical experts
Personnel Noise Summary