Digital Signal Processing and System Theory

Talk Michael Brodersen


Real-Time Signal Enhancement for Breathing Masks

Date: 21.11.2013, 13:00h - 14:00 h
Room: Aquarium

Michael Brodersen
CAU, Kiel, Germany,


If todays firefighters want to communicate with each other while wearing a breathing mask during fire-fighting or rescue operations, there are numerous technical aids available. Modern breathing masks are equipped with microphones and loudspeakers (inside and outside the mask) and also a connection to wireless devices is state of the art. In this way, firefighters can communicate with each other via radio or also directly by recording the speech signal within the mask and playing it back via the loudspeakers located outside the mask. Due to the reproduction of the speech signal via the loudspeakers the signal couples back to the microphone inside the mask. This can cause a disturbing feedback, which might lead to an instable system. The signal quality and also the disturbing feedback can be significantly improved by the use of digital signal processing. Therefore, the aim of this thesis is to create a real-time signal enhancement system for three different communication paths

  • from the radio to the loudspeaker inside the mask (head phone),
  • from the microphone to the base station of the radio and
  • from the microphone to the loudspeakers outside the mask.
Due to these different communications paths, different algorithmic approaches should be applied to overcome problems like background noise, breathing noise, varying speakers, etc. To realize these algorithms an existing real-time framework (KiRAT) can be utilized, which already provides usefully features like for example an audio connection or a filter bank.