In-Ear Dosimetry: Observations from Initial Field Studies

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