Evaluation of a calculation method of noise exposure from communication headsets

Specialized standardized methods for the measurement of noise exposure from communication headsets or sound sources close to the ear include the Microphone in Real Ear and manikin techniques, as specified in ISO 11904-1/2. The 2013 version of Canadian standard Z107.56 introduced a simpler calculation method to increase accessibility to communication headset exposure assessments for the widest range of stakeholders in hearing loss prevention. The calculation method only requires general and widely accessible sound measurement equipment and basic computational steps that account for the main determinants of exposure such as the background noise around the user, the sound attenuation of the communication headset, and the expected communication duration and effective listening signal-to-noise ratio. This paper reviews recent research on the effects of the spectral and temporal characteristics of the background noise and the headset configuration on the speech listening level. Results indicate that the listening level is largely insensitive to spectral and temporal variations in the background noise and that A-weighted noise level is a good predictor of listening level once headset attenuation is taken into account. It is also found that one-sided headsets increase exposure by 6-7 dB compared to two-sided headsets due to binaural summation.