Overexposure to noise is known to cause permanent hearing damage, and as a result, employers are required to implement suitable health monitoring measures when workers will be exposed to loud noises.  A noise dosemeter is the most reliable way to determine a workers noise exposure.  

In this project a series of commercially available microelectromechanical system (MEMS) microphones were explored as the sensing element of an electronic yarn.  The microphones were first soldered onto fine multi-strand copper wire and then protected with a micro-pod crafted with a UV-curable resin to protect the microphone and make it washable.  The ensemble, along with additional packing fibres, was then covered with a fibre sleeve to form an acoustic sensor yarn (NTU propitiatory E-yarn technology).  Finally, the acoustic sensor yarn was incorporated into a knitted helmet cover using computerised flat-bed 3D knitting technology.  The knitted helmet cover also included all hardware necessary to use the sensor yarn as a dose-meter.

The project was developed for the Dstl Accelerator Enduring Competition (2017/2018) which covered the challenges of human performance, protection, and situational awareness.  The acoustic sensing helmet cover was created and validated in a laboratory environmental at Technology Readiness Level 3 – 4 (TRL 3 – 4).

A video showing the developed acoustic sensing helmet cover is available below.

Details of this innovation are available in the article ‘Developing an Acoustic Sensing Yarn for Health Surveillance in a Military Setting‘.