influence of headset, hearing sensitivity, flight workload, and communication signal quality on...
TRANSCRIPT
Influence of Headset, Hearing Sensitivity, Flight Workload, and Communication
Signal Quality on Flight Performance and Communications: An Army Black Hawk
Helicopter Simulator Experiment
Disclaimer
The views, opinions, and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of the Army position, policy, or decision, unless so designated by other official documentation. Citation of trade names in this report does not constitute an official Department of the Army endorsement or approval of the use of such commercial items.
Acknowledgments
• Dr. John Casali• Dissertation committee members• Bose, Corp.• CEP, Inc.• USAARL• Participating pilots
Background
• Challenges to Army rotary-wing pilots
• Noise
• Communication demand• Flight workload• Decreased hearing sensitivity
Background
• Current approaches to meeting challenges• Hearing protection
• Passive earplugs
• Communication devices• Communications earplug (CEP)• Active noise reduction (ANR)
• Hearing loss waivers• Estimated 10% of aviators
Background
Class 500 Hz 1000 Hz 2000 Hz 3000 Hz 4000 Hz 6000 Hz 1/1A 25 25 25 35 45 45
2/2F/3/4 25 25 25 35 55 65
• Pure tone air and bone conduction testing• Tympanometry• Acoustic reflex testing• Speech reception threshold•Speech discrimination, monaurally at 40dBSL, and binaurally at most comfortable listening level (MCL)• In-flight evaluation
Independent Variable – Headset Configuration
David Clark headset with CEP
Bose Aviation X ANR headset
Passive David Clark headset with passive foam earplug
Independent Variable – Flight Workload (Perceptual)
Visual Meteorological Conditions (VMC)
No ceiling6 SM visibility
Low visibility, fog1.75 SM visibility
Instrument Meteorological
Conditions (IMC)0 SM visibility
Independent Variable – Flight Workload (Psychomotor)
Low workloadStraight and level flight followed by turns to various headings
Medium workloadStraight and level flight followed by turns to various headings combined with altitude changes
High workload Straight and level flight followed by turns to various headings combined with altitude and airspeed changes
Independent Variable – Flight Workload (Communication)
Low workloadOne-part radio commandEx. “Turn right heading 270°.” Read-back task during maneuver
Medium workload
Two-part radio commandEx. “Turn right heading 290°, climb and maintain 2500’.”Read-back task during maneuver
High workloadThree-part radio commandEx. “Turn right heading 270°, climb and maintain 2500’ while decelerating to 100 knots.”Read-back task during maneuver
Independent Variable – Signal Quality
• Three levels• Earphone output signal quality was manipulated and
quantified with the Speech Intelligibility Index (SII) method of predicting speech intelligibility
• SII levels• 0.4 (poor) • 0.6 (average)• 0.8 (good)
Blocking Variable – Hearing Levels
1. Audiometric pure-tone air-conduction thresholds not exceeding 25 dBHL at 500, 1000, or 2000 Hz, not exceeding 35 dBHL at 3000 Hz, and up to 55 dBHL at 4000 Hz in either ear
2. Audiometric pure-tone air-conduction thresholds exceeding 25 dBHL at 500, 1000, or 2000 Hz, exceeding 35 dBHL at 3000 Hz, and exceeding 55 dBHL at 4000 Hz
Dependent Measures
• Flight control performance• Heading deviation • Altitude deviation• Airspeed deviation
• Communications intelligibility (ATC readbacks)• Subjective workload measure• Subjective situation awareness measure• Subjective ratings of headset comfort and
speech intelligibility
Participants
• Active duty, Department of the Army civilians, and contract helicopter pilots
• Instrument rated• Current ‘full flying duties’ flight physical• Had flown a military helicopter or military
simulator within the past year
Participant Demographics
Group 1 Group 2
Age range 20-51 33-66
Age median 31 52.5
Age mean 33.4 50.2
Flight hours range 75-12,000 1,100-11,000
Flight hours median 200 4350
Flight hours mean 1678.5 4770
Mean Hearing Levels
RIGHT 250Hz 500Hz 1kHz 2kHz 3kHz 4kHz 6kHz 8kHz
Group 1 9.0 7.0 6.0 4.0 9.0 10.5 14.0 11.0
Group 2 13.0 14.5 19.0 29.5 41.0 51.5 51.5 54.5
LEFT 250Hz 500Hz 1kHz 2kHz 3kHz 4kHz 6kHz 8kHz
Group 1 8.5 7.5 7.5 6.0 12.0 17.0 15.5 15.0
Group 2 18.5 19.5 22.5 30.5 54.5 67.5 69.5 69.0
Apparatus
Results
• Flight performance• Heading deviation• Altitude deviation• Airspeed deviation
• Communications intelligibility• Workload• Situation awareness• Headset comfort/speech intelligibility
Flight PerformanceAltitude deviation – Interaction effect of workload/signal quality
Flight PerformanceAirspeed deviation – Interaction effect of
workload/signal quality
Flight PerformanceAirspeed deviation – Interaction effect of
group/headset
Communications IntelligibilityATC readbacks – Interaction effect of
workload/signal quality
Communications Intelligibility
ATC readbacks – Interaction effect of group/headset
WorkloadModified Cooper-Harper – Interaction effect of signal
quality/workload
WorkloadModified Cooper-Harper – Interaction effect of
group/headset
WorkloadModified Cooper-Harper – Interaction effect of
group/workload
Situation AwarenessSART – Interaction effect of group/headset
Situation AwarenessSART – Interaction effect of group/workload
Conclusions
• Workload level, signal quality level, and headset choice influence pilot performance – significant difference trends:– between low and medium workload– between average and poor signal quality– with high workload/poor signal quality conditions– with hearing impaired group using passive
headset/passive earplug combination
Limitations of Research
• No co-pilot• Artificially increased primary pilot workload
• Single ATC radio• Artificially decreased primary pilot communication
workload
• Number of hearing loss categories• Unable to draw conclusions on level of hearing loss at
which performance degrades
Recommendations for Future Research
• Similar study in an actual aircraft• Similar study to examine how variables in this study
affect intra-cockpit coordination• More narrowly defined hearing ability categories• Isolated communication workload• CEP comfort• ANR technology• Functional hearing evaluation
