RESUMEN
Based on today's common hearing aid design and technology, the team of researchers successfully designed a DPI which allows the worker to be "protected" against loudness and in the same time guarantee a good level of communication and perception of the surrounding environment. The design of this new device is very much similar to a standard BTE hearing aid which allows the use of an active DPI very comfortable, robust and easy to use. The research using the prototypes was divided into 3 phases: Phase 1: 24 volunteers coming from non-industry companies did undergo a specific trial protocol. Phase 2: 6 workers coming from a mining company did undergo the same protocol used in Phase 1. Phase 3: The Acoustics Laboratory from the "Energetica" Department of the Polytechnic of Turin (University/Institute) took objective measures for the DPI attenuation figures used in phase 1 and 2.