Introduction

        Noise-induced hearing loss (NIHL) related to firearm use by the military has long been the topic of research, and in recent years NIHL caused by recreational firearm use has garnered interest from several studies. It was estimated in 2017 that civilians around the world own around 650 million firearms. Recreational firearms create peak SPLs ranging from 140 to 175dB, with most firearms (excluding small-caliber 0.17 and 0.22 rifles and air rifles) ranging between 150 and 165dB peak SPLs (Meinke et al., 2017). High intensity impulse sounds such as gunshots damage the fine structures of the cochlea, resulting in noise induced hearing loss. Those that shoot firearms are at risk for bilateral NIHL due to the nature of the action of shooting (Meinke et al, 2017). Some caliber ammunition such as 50 caliber, are large enough that they travel faster than the speed of sound. A bullet travelling faster than the speed of sound creates what is called an N-wave. An N-wave consists of the bullet travelling through the air and the pressure envelope around it breaking the sound barrier, followed by a drastic reduction in sound pressure and then a secondary sound wave produced by the muzzle blast. A study from 2018 tested to see if there was a difference in distance for the dangerous sound levels created by an N-wave and they found that any distance in the path of the N-wave is unsafe for human hearing, even more so than that of a smaller caliber bullet producing a single sound wave (Flamme & Murphy 2018). Though recreational firearm use poses a major risk to the hearing health of shooters, potential damage is reduced through the use of hearing protection devices (HPDs).

            While HPDs are the most effective way to reduce the impact of impulse noise such as that produced by gunshots, they are labeled with single number noise reduction ratings (NRRs) which are supposed to tell the use how much noise they are capable of attenuating. However, the NRRs are not as accurate as consumers may think, NRRs are obtained in ideal laboratory conditions where the HPDs are placed appropriately by professionals (Biabani, Aliabadi, Golmohammadi, and Farhadian, 2017). According to a study from 2017 the following subtractions should be made from manufacturers’ labeled NRRs (which are in dB), 25% for earmuff style (meaning a 50dB label NRR would be corrected to 37.5dB), 50% for formable earplugs (50dB label would be 25dB corrected), and 75% for all other styles (50dB would be corrected to 12.5dB) (Biabani et al, 2017). One of the main reasons for these drastic subtractions from label NRRs is because of variation caused by the user and their application or insertion of the HPD. HPDs are often improperly placed on or inside the ear (Biabani et al, 2017). The authors also argue that the unreliability of label NRRs is one of the main reasons why it is difficult to create an efficient hearing conservation program (Biabani, et al 2017).

            A study from 2018 sought to evaluate the efficacy of several youth hearing conservation programs. A total of ten programs were evaluated, 8 from the United State and 2 from Belgium. There were set requirements for the hearing conservation programs to be comparable in the researchers’ study such as inclusion and criteria of the program. When compared, all of the hearing conservation programs were flawed in some way. Many of the programs lacked clarity in their intervention and several lacked what the researchers called “critical information” that would aid future hearing conservation programs (Khan, Bielko & McCallagh 2018).

            Recreational firearm use is a common hobby and sport in the United States for youth and adults alike. Similar to members of the military, prolonged and repeated use of firearms exposes recreational shooters to dangerous sound intensity levels. Without proper hearing protection, exposure to the intensity levels produced by firearms will likely produce varying amounts of noise induced hearing loss in shooters. The purpose of this project is to determine how attitudes towards hearing protection devices and hearing loss differ between different age groups, and then to use already existing hearing conservation materials with information collected from this study to cater hearing conservation materials to local shooters.