Method for protected noise exposure level assessment under an in-ear hearing protection device: a pilot study

Area of Science:

• Occupational health and safety
• Acoustics and noise control
• Wearable sensor technology

Background:

• In-ear noise dosimeters (IEND) are increasingly used to measure worker noise exposure with hearing protection devices (HPD).
• Commercial IENDs struggle to differentiate between actual noise and wearer-induced disturbances (WID), affecting accuracy.
• Accurate measurement of in-ear sound pressure levels (SPL) is crucial for assessing hearing protection effectiveness.

Purpose of the Study:

• To propose a novel method for in-ear noise dosimeters to reject wearer-induced disturbances (WID).
• To enable on-site calculation of accurate in-ear sound pressure levels (SPL) and hearing protection levels.
• To validate the proposed method against a reference technique for improved noise exposure assessment.

Main Methods:

• Estimating in-ear SPL by filtering outer-ear microphone signals with a modeled hearing protection device (HPD) transfer function.
• Rejecting wearer-induced disturbances (WID) captured by the in-ear microphone from the sound pressure level (SPL) calculation.
• Validating the WID rejection method by comparing its results to a reference measurement method.

Main Results:

• The proposed method effectively distinguishes between in-ear noise and wearer-induced disturbances (WID).
• Accurate estimation of residual sound pressure levels (SPL) and hearing protection levels was achieved.
• The method demonstrated merit in improving the accuracy of on-site noise exposure assessments.

Conclusions:

• A new algorithm effectively rejects wearer-induced disturbances (WID) in in-ear noise dosimeters (IEND).
• The proposed method allows for accurate on-site measurement of hearing protection levels.
• Integration of this algorithm into future IENDs is recommended for enhanced occupational noise monitoring.