In-Ear Dosimetry: Observations from Initial Field Studies

1. In-Ear Dosimetry:Observations from Initial Field Studies Work by: Trym Holter, Jarle Svean, Georg E. Ottesen: Nacre AS Olav Kvaløy, Viggo Henriksen, Odd Kr. Ø. Pettersen: SINTEF ICT AsleMelvær : Statoil ASA

2. Outline • HPD technology background • In-ear noise dosimetry – why and how • Data from field studies • Conclusions

3. Where the technology fits CommunicationinNoisy Scenarios Safe HearingProtection Situational & SpatialAwareness

4. Where the technology fits CommunicationinNoisy Scenarios Safe HearingProtection Situational & SpatialAwareness

5. Outer microphone: Captures sound outside the noise attenuating earplug – ambient sound • Inner microphone: Captures sound inside the ear canal. Used for: • voice capture (outgoing comms after processing) • ANR (active noise reduction) control signal • Loudspeaker: Presents an optimized mix of: • ambient sound (talk-thru) • incoming communications sound • ANR How it works Basic principle Sound is captured by the microphones and signal processing is done by the electronics. The sound signals are adapted before they are sent to the loudspeakers and radio outputs.

6. Barriers against NIHL Passive attenuation

7. Barriers against NIHL Passive attenuation Automatic fit check at start-up – alarm if not OK

8. Barriers against NIHL • Passive attenuation • Automatic fit check at start-up – alarm if not OK • Sound processing techniques for safe hearing in noise • Talk-through • Impulse noise protection • Digital Active Noise Reduction

9. Barriers against NIHL • Passive attenuation • Automatic fit check at start-up – alarm if not OK • Sound processing techniques for safe hearing in noise • Talk-through • Impulse noise protection • Digital Active Noise Reduction • In-ear noise exposure measurement with alarm

10. Noise exposure estimation – how it is today Traditional approaches are typically based on: • Noise surveys • HPD attenuation estimates • Statistical approach • Estimates are poor and therefore must be conservative • Typically used to set work time restrictions

11. Noise exposure estimation – our new approach • In-ear noise exposure measurement (left + right ear) • Alarm (sound + visual) at pre-set exposure limit • System can also monitor unprotected exposure (left + right side) • Valuable data for occupational hygienists • Deterministic approach

12. Field test – example data Blue: noise in earcanal Red: external noise

13. Field test – example data Blue: noise in earcanal Red: external noise 5dB gain

14. Field test – example data Incoming radio Blue: noise in earcanal Red: external noise

15. Field test – example data Blue: noise in earcanal Red: external noise ≈15dB

16. Field test – example data Blue: noise in earcanal Red: external noise ≈ 30dB

17. Field test – example data Blue: noise in earcanal Red: external noise ≈ 80dBA

18. Field test – example data Blue: noise in earcanal Black: accumulated noise dose

19. Next project: MENO • MENO consortium: Statoil, SINTEF, Nacre, NTNU, UiB • MENO will conduct a field study starting in 2011 • 100 units fielded on two different Statoil installations in the North Sea • MENO will produce high volumes of detailed noise exposure data • MENO aims to improve understanding of: • Attenuation of earplug in everyday use (‘type F’ data) • Earplug use patterns • Mechanisms behind noise induced hearing loss • The MENO database could at some stage be made available to the wider research community

20. Summary and conclusions • Traditional hearing conservation programs rely on: • Inaccurate estimates of hearing protection performance • Infrequent measurements of noise • The approach presented here offers: • Actual noise exposure measurements close to the eardrum • An additional barrier against NIHL • Data from initial field studies were presented • The data illustrates how incoming communications contribute significantly to the total exposure