How can audio technology improve working conditions?

Hearing is one of the most important human senses. The fact that we can perceive sound helps us to locate and classify sound sources and forms the basis of our speech communication. The healthy hearing system is astonishingly robust towards adverse acoustic conditions such as background noise, competing speech or reverberation. In modern societies, however, hearing deficiencies are widely spread. Recent figures estimate that about 16% of the population in industrialized countries suffer from hearing deficiencies [Shield, 2006]. Due to age-related deterioration of nerve cells in the inner ear, this percentage is much higher in older subgroups of the population (cf. Figure 1). Different estimates report that between 37% and 56% of the population aged 60 to 70 years suffer from hearing loss [Sohn, 2001; Davis, 2003; Johansson and Arlinger, 2003; Uimonen et al., 1999]. These figures gain particular importance in the light of the demographic change. Recent projections estimate a significant increase in all population groups aged 55 years or older between 2005 and 2030 and, at the same time, a considerable decrease in the younger population groups [European Commission, 2005]. This development will have a particular impact on European economies, since Europe will be the first region to experience demographic ageing. The populations in the neighboring regions Africa or Asia will start to age later given their presently considerably lower average age [European Commission, 2005]. In terms of hearing deficiencies, the demographic change will significantly increase the number of hearing-impaired people. A recent estimate expects the number of people suffering from hearing loss to rapidly increase in the following ten years and to almost double by 2030 [Shield, 2006]. The effect of ageing societies is not restricted to retired people. On the contrary, the employment rates of older workers are projected to increase massively from 40% in 2004 for the EU-25 to 47% by 2010 and 59% in 2025 [European Commission, 2007]. The increase of the proportion of older workers leads to new requirements concerning ergonomic conditions at workplaces. One important factor fundamentally related to ergonomics is acoustic communication. Both a comfortable speech communication and the perception of acoustic signals, e.g. alarm signals, are of outmost importance in modern economic processes. However, acoustic communication becomes increasingly difficult for workers with hearing impairment since part of the speech information cannot be extracted from the signal anymore.