Existing hearing protection systems provide effective protection against hearing damage caused by noise. They can, however, restrict users’ hearing ability and their acoustic interaction with their surroundings, especially with their work colleagues. If staff do not understand what their colleagues are saying or acoustic warning signals are not recognised or are misinterpreted, this can lead to misunderstandings, uncertainty or even accidents.

According to the current state of knowledge, this risk occurs especially with level-dependent hearing protection systems, which are already established in practice. Level-dependent means that the amount of sound allowed through is controlled electronically. If the ambient environment is quiet, the sound is let through or even amplified. If it is noisy, the sound is drastically attenuated. The advantage of this technology is that you can leave your hearing protectors on when it is quiet, and you want to talk to a colleague. If it suddenly becomes noisy, your hearing is still protected.

A better understanding of hearing protectors

However, recent studies by Fraunhofer IDMT in Oldenburg suggest that wearing such hearing protectors could massively alter important sound properties – such as differences in acoustic level between the two ears when sound comes from the side. This can lead to the wearer taking significantly longer to correctly identify the direction of a corresponding sound, for example.

That is why the main objective of the “ProSA” project is to lay the ground work for evaluating hearing protection systems in the future through practical and time-saving measuring techniques, taking the most important effects on auditory characteristics into consideration. With the help of the research results, employers’ liability insurers and accident insurers as well as institutions such as the Institute for Occupational Safety and Health (IFA) of the German Social Accident Insurance (DGUV) should be able in future to make concrete recommendations for hearing protectors for specific areas of application. This is particularly desirable for staff who are obliged to wear hearing protectors in their everyday work and at the same time need to hear properly. The aim here is to raise acceptance for wearing hearing protection in the workplace. In the long term, this should lead to fewer work-related hearing impairments.

“The special thing about the project is our many cooperation partners in the Research Support Group. Thanks to their expertise, we can ensure that the research work is geared to practical questions and problems,” reports Dr Jan Rennies-Hochmuth, Head of Group Personalized Hearing Systems at Fraunhofer IDMT.

Needs-based hearing protectors for every workplace

Currently, the certification of hearing protectors is based solely on measurement based evidence of sufficient protection against noise. To deliver detailed recommendations for suitable hearing protectors adapted to the needs of specific workplaces, it is important to be able to compare products on the basis of their capacity to preserve wearers’ auditory perception of their environment and ability to communicate. However, fundamental knowledge about which aspects of auditory situational awareness need to be recorded for this purpose and about the methods most suitable for achieving this are so far lacking. The project aims to close these knowledge gaps, which is why, among other things, the researchers will examine speech intelligibility when users are confronted with noise sources from different directions and detection errors of warning signals when exposed to background noise.

The Research Support Group for the “ProSA” project comprises the Institute for Occupational Safety and Health (IFA) of the German Social Accident Insurance (DGUV), Lärm und Gehörschutz Consult Peter Sickert (LGC-PS), the German Social Accident Insurance Institution for the Foodstuffs and Catering Industry (BGN), for the Woodworking and Metalworking Industries (BGHM), for Commercial Transport, Postal Logistics and Telecommunication (BG Verkehr) and for the Energy, Electrical and Media Products Sectors (BG ETEM), as well as the Hearing Protection Working Group of the Personal Protective Equipment Department of the German Social Accident Insurance (DGUV), the German Institute of Hearing Aids (DHI) and the Federal Institute for Occupational Safety and Health (BAuA).

Hearing, Speech and Audio Technology HSA at Fraunhofer IDMT in Oldenburg

Founded in 2008 by Prof. Dr. Dr. Birger Kollmeier and Dr. Jens-E. Appell, the Fraunhofer Institute for Digital Media Technology IDMT’s Branch for Hearing, Speech and Audio Technology HSA stands for market-oriented research and development with a focus on the following areas:

• Speech and event recognition
• Sound quality and speech intelligibility
• Mobile neurotechnology and systems for networked healthcare

With in-house expertise in the development of hardware and software systems for audio system technology and signal enhancement, the employees at the Oldenburg site are responsible for transferring scientific findings into practical, customer-oriented solutions.
Through scientific cooperation, the institute is closely linked to the Carl von Ossietzky University, Jade University of Applied Sciences, and the University of Applied Sciences Emden/Leer. Fraunhofer IDMT is a partner in the »Hearing4all« cluster of excellence.