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

3

Boeing JSF

4

Lockheed JSF

5

Lockheed/Boeing F-22

6

P&W F-119 Engine

7

Nimitz Class Nuclear Carrier

8

Crew Positioning

9

Crew Positioning

10

Crew Positioning

11

Carrier Crew Positioning

12

Navy/AF JSF VA Team

13

Carrier Crew Positioning

14

USAF Crew Positioning

15

USAF Crew Positioning

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

34

Deep Insert Custom Plug PrototypeTechnology Demonstration

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