Speech Perception in Noise with Active and Passive Hearing Protectors: Acoustical Analysis

This research project has compared the speech recognition scores for test fragments recorded in different kinds of realistic industrial noise, with both standard and active earplugs. The standard protectors block the incoming sound whereas the active work level-dependent. Acoustical analyses reveal the importance of global input sound pressure levels, especially for speech recognition with standard protectors. Furthermore, the active protector with maximal amplification hinders communication, possibly because it does not sufficiently preserve temporal variations and distorts the spectrum. Finally, the tested active protector with minimal amplification does not benefit entirely from the unmasking effects of binaural hearing. This project shows that speech recognition can be linked to the acoustical features of the signals under hearing protectors. A more formal relationship could facilitate further development of active protectors but a wider range of test samples is needed to reach a sufficiently accurate model.