Detection of alarms and warning signals on an digital in-ear device

A majority of workers in industrial environments must wear hearing protection devices. While these hearing protectors provide increased safety in terms of auditory health, in some conditions they also have the adverse effect of preventing individuals from hearing alarm and warning signals which seriously compromises their safety. Recent advances in the field of microelectronics allow the integration of tiny digital signal processors inside hearing protection devices. This paper develops new algorithms to automatically detect alarm signals in the digitized audio stream fed to the processor. This detection is performed in real-time with low latency to quickly inform the user of a dangerous situation. The algorithms were also optimized to require low computational resources due to the limited processing power of typical embedded electronic devices. The proposed algorithms detect periodicity of the signal amplitude in a determined frequency bandwidth. The system was simulated with a database of alarm signals from a major North-American manufacturer of industrial alarms and warning signals, mixed with typical environmental noises at signal-to-noise ratios ranging from 0 to 15dBA. The results show an average true-positive recognition rate of 95% for pulsed alarms compliant to the ISO 7331 standard. The system can be optimized for specific alarms which results in near 100% true positive and 0.2% false positive recognition rates. Alarms and warning signals are widely use in industry to promptly alert workers of events that can compromise their safety. In practice, however, their efficiency can be dramatically affected by several factors, among which the use of hearing protectors by workers is the most severe. Designing digital hearing protectors with built-in alarms and warning signal detectors may considerably improve the situation. ► Deals with a critical issue in occupational health& safety: how to protect workers against loud noise while still letting them hear important warning signals? ► Takes advantage of recent advances in the field of microelectronics to integrate of tiny digital signal processors inside hearing protection devices to let warning signal be fed to the miniature loudspeaker of the hearing protector. ► Presents original alarm detection algorithms for real-time and low latency implementation while respecting the low processing power of typical embedded electronic devices.