Speech recognition in noise with active and passive hearing protectors: a comparative study
Annelies Bockstael, Bart Vinck, Dick B. Botteldooren · Ghent University Academic Bibliography (Ghent University) · 2009
A common argument for not wearing passive hearing protection is that they create unsafe situations by hampering communication.Making sound attenuation more comfortable is one of the incentives for the development of so-called 'augmented' hearing protectors.However, several studies fail to clearly demonstrate their benefits on signal perception in noise over standard passive protectors.Apparently, the positive effects of these protectors are not clear-cut and testing of new prototypes is essential.Within the class of augmented protectors 'passive', i.e. without electronics, and 'active', i.e. with electronics, can be distinguished; in this project, speech perception with custom-made active earplugs is compared to passive custom-made earplugs.The active protectors amplify the incoming sound to the maximum safe level, or to a user defined fraction of this level.For the experiment minimal and maximal settings are compared.In the concrete 20 different speech-in-noise samples are presented to 60 normal-hearing subjects and the speech recognition is scored.The background noise is selected from realistic industrial noise samples with different loudness, frequency and temporal characteristics recorded with a Head And Torso Simulator (HATS).The speech is chosen from standardized word lists used for speech audiometry.The speech-in-noise samples are created by presenting the mixture of speech and noise to the HATS with unoccluded simulators and with passive and active protectors.The results suggest that the performance of the hearing protectors strongly depends on the kind of background noise.The active protectors with minimal amplification outclass the other protectors for the most difficult and the easiest noise conditions, but they also limit binaural listening.For the remaining noise conditions, the passive protectors clearly surpass their active counterparts.