Effect of hearing protection attenuation on impulse insertion loss and kurtosis

Kurtosis (the fourth standardized moment of the sound pressure) has been used to assess the additional risk of hearing loss for complex or impulsive noise exposures. Murphy et al. [2012] reported the impulse peak insertion loss of five hearing protection devices (HPDs) for firearm impulse noise. Fackler et al. [2017] reported a spectral insertion loss for several HPDs assessed with firearm and shock tube impulse noise sources. Murphy [2019] previously reported the effect of five hearing protection devices on the kurtosis and insertion loss assessed with jackhammer noise. Unprotected Jackhammer noise exhibited kurtosis values between about 15 to 17, whereas protected exposures exhibited kurtosis between about 3 to 12. Anderson and Argo [2022] reported that insertion loss was unaffected by kurtosis level for seventeen HPDs measured on an acoustic test fixture under headphones. This paper will apply the complex transfer functions from Murphy et al. [2012] to the jackhammer noises measured by Murphy [2019]. The levels of the unoccluded noises transformed to the ear canal of the fixture will be compared to occluded jackhammer noises levels measured in the fixture.