Hearing Protection Pilot Health and Safety

1. Hearing Protection Pilot Health and Safety

2. Pilot‘s Hearing Health and Safety Noise is a known problem in the commercial cockpit for two primary reasons: • Interference with communications • Hearing damage from years of turning up the intercom volume to overcome the background noise of the airplane This problem not only affects the quality of life of pilots, but can reduce the length of their active professional career Sennheiser NoiseGard™ maintains a pilot‘s normal hearing thresholds so he is not required to increase the volume of incoming communications

3. Noise Canceling Headsets • “Noise-canceling headsets cancel noise through a combination of physical means and electronic means. While this technology can have many beneficial effects such as providing clearer communications, reduced pilot fatigue, and added comfort, electronic attenuation of important environmental sounds and alarms may occur.” • So, the benefit of noise protection including active noise reduction (ANR or by Sennheiser, NoiseGard™) is clear, but the design must be such that the ANR does not affect the ability of the pilot to hear critical sounds from the aircraft. • Sennheiser NoiseGard™ attacks the low frequency noise, below the frequencies of alarms, which is responsible for the ‘upward spread of masking’ effect (see Figure 1). This masking effect is what causes us to have difficulty hearing conversation or alarms in frequencies above 1000 Hz.

4. Sennheiser NoiseGard™ Attacks Low Frequencies

5. Pilot Hearing Loss • Evidence of pilot hearing loss from “An Investigation of Unilateral Hearing Loss amongst Professional Flight Crew; British Airways” According to Dr Michael Bagshaw: Head of Occupational and Aviation Medicine, British Airways: • Ambient noise levels on the flight decks of the airline’s aircraft were found to be between 70 dB(A) and 79 dB(A) averaged over the flight. Noise levels from headsets were measured at between 77 dB(A) and 89 dB(A). On 40% of flights noise levels were 85 dB(A) or higher, and on 80% of flights noise levels were 80 dB(A) or higher. The higher noise levels will give noise exposure over a working day in excess of 85 dB(A) on perhaps 30% - 40% of flights. If repeated regularly over the long term, this could result in some degree of hearing impairment for some flight crew. • The prevalence of hearing loss which could be noise induced was found to be of the order of 18.5% - 27.5% amongst the flight crew of this international airline. This information served primarily as a trigger to search for the source of occupational auditory hazard for flight crews.

6. Pilot Hearing Loss Evidence of pilot hearing loss from “Assessment of noise exposure in commercial aircraft cockpits” (interim report, December 1998) • Durand R. Begault & Elizabeth M. Wenzel, Ames Research Center • Questionnaire data from 64 pilots were analyzed (see Begault, et al. 1998). Within specific age groups, the proportions responding positively for hearing loss and tinnitus exceed the corresponding proportions in the general population reported by The National Center for Health Statistics (NCHS).

7. Noise Also Affects Job Performance Noise also affects individual performance in the work-place. • Evidence of performance degradation and fatigue from FAA Civil Aerospace Medical Institute, according to Melchor J. Antuñano, M.D., and James P. Spanyers: • High noise levels can have serious effects such as impaired concentration, fatigue and insomnia. Pilots may demonstrate this in the form of irritability, anger and anxiety. High ambient noise is only part of the noise problem that pilots may experience in the cockpit. • More evidence of noise impairing performance from Upadhyay (1986) • Noise reduced by 15%, increased the work of assembly regulators by 37%, errors reduced by 12%, office work improved by 9% and typists errors fell by 24%. Noise reduction also decreased turnover by 47% and absenteeism by 38%. Less noise leads to better morale which, in turn, influences performance.

8. Ambient Noise is Just the Start of the Problem • Radio communications must be 10 to 15 dB or louder than the ambient noise in order to be heard, however, intelligibility decreases at high volume settings so increasing the radio volume does not always help in understanding radio communications. When the volume is increased crewmembers must speak at high volume to be heard by others in a noisy cockpit, which also reduces intelligibility. • It’s not just continuous background noise that can cause hearing damage and distraction. Noise can also occur as peak-level bursts through the intercom as well. See ‘Peak-Level-Protection’ below.

9. The FAA Does Publish Noise Standards • 13.5.2.7 Operational areas. • Ambient noise in areas requiring frequent phone use or requiring occasional speech communication (for example, operations centers, control rooms, tower cabs, and dynamic simulation rooms) at distances up to 4.6 m (15 ft) shall not exceed 55 dB(A) or 47 dB PSIL-4; • 13.5.2.8 Equipment areas. • Ambient noise in areas requiring frequent telephone use or frequent speech communication (for example, computer rooms, engineering areas, equipment rooms, and telephone switching centers) at distances up to 1.5 m (5 ft) shall not exceed 65 dB(A) or 57 dB PSIL-4. • In this document, the FAA mandates quiet background noise levels (55 – 65 dB(A)) in work environments which require clear communications. Given these requirements, how much more important is adequate noise protection in the cockpit?

10. Noise Contributes to Pilot Fatigue • The environment and nature of the work can further magnify the effects of sleep debt and circadian rhythms. Environments with dim lighting, limited visual acuity (e.g. due to weather), high temperatures, high noise and high comfort tend to enhance fatigue. Also, a worker's susceptibility to fatigue is increased by tasks where attention must be sustained for long periods, and those which are long, repetitive, paced, difficult, boring and monotonous.

11. Professional Headset Requirements • Certification requirements • Pilots are required to use TSO certified headsets in Part 121 operations (see Part 21 Subpart O Part 25). Non-TSO certified headsets do not meet the minimum performance standards established by the FAA. • Sennheiser ANR (NoiseGard™) : • The only headset manufacturer that also produces their own professional headset transducers (speakers and microphones). • These transducers are the key elements in the NoiseGard™ circuit. It is the interaction of these elements which determine the stability of the ANR system. Stability is that characteristic which prevents spurious noise from being introduced into the system when there are abrupt changes to the acoustic environment.

12. Sennheiser Unique Features • Peak-Level-Protection • Peak-Level-Protection safeguards your ears from volume peaks transmitted by the headphones above 110 dB • Electronic Stereo Talk-Through: • This allows ease of communication while retaining hearing protection without the necessity of an intercom • The FAA considers the ‘pseudo hot-mic configuration (when the intercom control is held in the ‘keyed’ position through the use of a temporary mechanism (e.g. rubber band)) will degrade the capabilities and lifetime of the aircraft communication system.

13. Professional Headset Requirements • Improved flight deck communications • Quality of audio signals • LHR pilots reported improved communications when UK NATS controllers began using Sennheiser headsets in ATC operations • Quality speakers and microphones reduce the incidents of missed directions and acknowledgements, enhancing safety • Study reveals NoiseGard™ impact on intelligibility: • Pilots required ATC transmissions to be repeated significantly fewer times when wearing any of the ANR-based headsets as opposed to the passive headset. • The interaction of STI with Headset shows that ANR-based headsets increase speech intelligibility enough to nearly maintain equivalent performance across the STI levels.

14. Contact details for further information Squadron Commanding Officers and Chairpersons of Sponsoring Committees who wish more detailed information on hearing health and safety may contact: Mr. Tim Mell Business Director, Aviation Sennheiser Canada tmell@sympatico.ca