In-Ear Dosimetry:Observations from Initial Field Studies
Work by: Trym Holter, Jarle Svean, Georg E. Ottesen: Nacre ASOlav Kvaløy, Viggo Henriksen, Odd Kr. Ø. Pettersen: SINTEF ICTAsle Melvær : Statoil ASA
2Outline
• HPD technology background• In-ear noise dosimetry – why and how• Data from field studies• Conclusions
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Communication inNoisy Scenarios
Situational & SpatialAwareness
Safe Hearing Protection
Where the technology fits
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Communication inNoisy Scenarios
Situational & SpatialAwareness
Safe Hearing Protection
Where the technology fits
5How 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.
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
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1. Passive attenuation
Barriers against NIHL
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1. Passive attenuation
2. Automatic fit check at start-up – alarm if not OK
Barriers against NIHL
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1. Passive attenuation
2. Automatic fit check at start-up – alarm if not OK
3. Sound processing techniques for safe hearing in noise– Talk-through– Impulse noise protection– Digital Active Noise Reduction
Barriers against NIHL
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1. Passive attenuation
2. Automatic fit check at start-up – alarm if not OK
3. Sound processing techniques for safe hearing in noise– Talk-through– Impulse noise protection– Digital Active Noise Reduction
4. In-ear noise exposure measurement with alarm
Barriers against NIHL
10Noise 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
11Noise 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
12Field test – example data
Blue: noise in earcanal
Red: external noise
13Field test – example data
Blue: noise in earcanal
Red: external noise
5dB gain
14Field test – example data
Incoming radio
Blue: noise in earcanal
Red: external noise
15Field test – example data
≈15dB
Blue: noise in earcanal
Red: external noise
16Field test – example data
≈ 30dB
Blue: noise in earcanal
Red: external noise
17Field test – example data
≈ 80dBA
Blue: noise in earcanal
Red: external noise
18Field test – example data
Blue: noise in earcanal
Black:accumulated noise dose
19Next 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
20Summary 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