**Rafal Mlynski \* and Emil Kozlowski**

Department of Vibroacoustic Hazards, Central Institute for Labour Protection–National Research Institute, Czerniakowska 16, 00-701 Warsaw, Poland; emkoz@ciop.pl

**\*** Correspondence: rmlynski@ciop.pl; Tel.: +48-22-623-3293

Received: 17 December 2018; Accepted: 29 January 2019; Published: 30 January 2019

**Abstract:** The use of hearing protectors in various noisy workplaces is often necessary. For safety reasons, auditory information may be required to correctly localize the direction of an auditory danger signal. The purpose of this study was to verify if the selection of a specific level-dependent hearing protector may be important for the ability to localize a vehicle back-up alarm signal. The laboratory conditions reflected industrial conditions, under which an impulse noise was emitted against a background of continuous noise. A passive mode and a level-dependent mode (maximum and incomplete amplification) were considered. Four different models of level-dependent earmuffs and one model of level-dependent earplugs were included in the tests. The tests enabled differentiation between the individual hearing protectors. The use of earplugs in level-dependent mode did not significantly affect the ability to correctly localize the back-up alarm signal. For the earmuffs, the global assessment of the impact of a mode change revealed that, depending on the model of the earmuffs, the impact may be insignificant, but may also result in considerable impairment of the ability to localize the back-up alarm signal.

**Keywords:** sound localization; level-dependent hearing protectors; back-up alarm; directivity of hearing; impulse noise; earmuffs; earplugs; auditory danger signal; warning signal; safety at work
