The actual amount of protection offered by a given hearing protection device (HPD) in the field is subject to great variations. Aside from the HPD itself, the amount and the format of the training material can influence the personal attenuation rating (PAR) that user obtain in the field. An active HPD equipped with an outer-ear microphone (OEM) and an in-ear microphone (IEM), can perform a measurement derived from the field microphone in real-ear (FMIRE) method to quickly estimate a personal attenuation rating (PAR) as per ANSI S12.71-2018. This method was used to characterize the PAR achieved by a population of 23 untrained participants of mean age 50 with an advanced hearing protection device, as well as characterize the effect of progressively more involved training material. The training material included three phases: written instructions with images, a training video, and personalized one-on-one training administered by the experimenter. The first phase training yielded an average PAR of 22 dB, with 78% of participant achieving a PAR of 20 dB or more and 9% achieving a PAR of 30 dB or more. The final phase training yielded an average PAR of 28 dB, with 96% of participant achieving a PAR of 20 dB or more and 48% achieving a PAR of 30 dB or more. This research enables insight into realistic levels of protection that an advanced HPD can provide in the field and allows to statistically predict the noise exposure of the population in specific environments. It also highlights the importance of providing proper education and training on the use of HPD and the value of measuring PAR in the field.