Evaluating the Relationship Between Kurtosis Loss and Spectral Insertion Loss for Musicians’ Hearing Protection Devices

Hearing protection devices (HPDs) are essential for musicians during loud performances to avoid hearing damage, but the standard Noise Reduction Rating (NRR) performance metric for HPDs metric says little about their behavior in a musical setting. One analysis tool being used to evaluate HPDs in the noise exposure research community is kurtosis measured in the ear and the reduction of noise kurtosis through an HPD. A musical signal, especially live music, will often have a high crest factor and kurtosis, so evaluating kurtosis loss will be important for an objective evaluation of musicians’ HPDs. In this paper, a background on kurtosis and filters affecting kurtosis is described, as well as a setup for generating high-kurtosis signals and measuring in-ear kurtosis loss through an HPD. Measurement results on a variety of musicians’ HPDs show that 83% of devices measured strongly reduce kurtosis, and that the kurtosis loss is likely an independent metric for performance because it is not correlated to the mean or standard deviation of the spectral insertion loss.