Speech intelligibility tests for hearing impaired persons using hearing protectors

Abstract

The combination of hearing impairment and the requirement to use hearing protection can create severe problems regarding situational awareness, signal audibility and communication ability. Nevertheless, for persons with a noise induced hearing loss a reliable protection against harmful noise is especially important. The German Social Accident Insurance (DGUV) founds a project that investigates a number of approaches to protect the vulnerable group of persons with a hearing loss at noisy workplaces, providing at the same time sufficient communication ability. In Germany, signal audibility with hearing protectors is addressed via a calculation using the sound attenuation of the hearing protector and a loudness model. But speech intelligibility, so far, cannot be quantified, neither by calculation nor standardized tests. The DGUV project investigates different types of speech tests respectively speech audiometry in the lab and the field. One aim is to quantify the effect of different types of hearing protectors (active and passive), another one to assess the feasibility of the different test approaches. We present results for simple, work-related messages in comparison to everyday sentences and a matrix sentence test. The effect of different hearing protectors is analysed in relation to the amount of hearing loss.